5005 lines
124 KiB
C
5005 lines
124 KiB
C
/*
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* kernel/sched.c
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*
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* Kernel scheduler and related syscalls
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*
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* Copyright (C) 1991-2002 Linus Torvalds
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*
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* 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
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* make semaphores SMP safe
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* 1998-11-19 Implemented schedule_timeout() and related stuff
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* by Andrea Arcangeli
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* 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
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* hybrid priority-list and round-robin design with
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* an array-switch method of distributing timeslices
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* and per-CPU runqueues. Cleanups and useful suggestions
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* by Davide Libenzi, preemptible kernel bits by Robert Love.
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* 2003-09-03 Interactivity tuning by Con Kolivas.
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* 2004-04-02 Scheduler domains code by Nick Piggin
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*/
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/nmi.h>
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#include <linux/init.h>
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#include <asm/uaccess.h>
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#include <linux/highmem.h>
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#include <linux/smp_lock.h>
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#include <asm/mmu_context.h>
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#include <linux/interrupt.h>
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#include <linux/completion.h>
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#include <linux/kernel_stat.h>
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#include <linux/security.h>
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#include <linux/notifier.h>
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#include <linux/profile.h>
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#include <linux/suspend.h>
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#include <linux/blkdev.h>
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#include <linux/delay.h>
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#include <linux/smp.h>
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#include <linux/threads.h>
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#include <linux/timer.h>
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#include <linux/rcupdate.h>
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#include <linux/cpu.h>
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#include <linux/cpuset.h>
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#include <linux/percpu.h>
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#include <linux/kthread.h>
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#include <linux/seq_file.h>
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#include <linux/syscalls.h>
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#include <linux/times.h>
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#include <linux/acct.h>
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#include <asm/tlb.h>
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#include <asm/unistd.h>
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/*
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* Convert user-nice values [ -20 ... 0 ... 19 ]
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* to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
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* and back.
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*/
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#define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
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#define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
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#define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
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/*
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* 'User priority' is the nice value converted to something we
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* can work with better when scaling various scheduler parameters,
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* it's a [ 0 ... 39 ] range.
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*/
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#define USER_PRIO(p) ((p)-MAX_RT_PRIO)
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#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
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#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
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/*
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* Some helpers for converting nanosecond timing to jiffy resolution
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*/
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#define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
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#define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
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/*
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* These are the 'tuning knobs' of the scheduler:
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*
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* Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
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* default timeslice is 100 msecs, maximum timeslice is 800 msecs.
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* Timeslices get refilled after they expire.
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*/
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#define MIN_TIMESLICE max(5 * HZ / 1000, 1)
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#define DEF_TIMESLICE (100 * HZ / 1000)
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#define ON_RUNQUEUE_WEIGHT 30
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#define CHILD_PENALTY 95
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#define PARENT_PENALTY 100
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#define EXIT_WEIGHT 3
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#define PRIO_BONUS_RATIO 25
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#define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
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#define INTERACTIVE_DELTA 2
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#define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
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#define STARVATION_LIMIT (MAX_SLEEP_AVG)
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#define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
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/*
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* If a task is 'interactive' then we reinsert it in the active
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* array after it has expired its current timeslice. (it will not
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* continue to run immediately, it will still roundrobin with
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* other interactive tasks.)
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*
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* This part scales the interactivity limit depending on niceness.
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*
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* We scale it linearly, offset by the INTERACTIVE_DELTA delta.
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* Here are a few examples of different nice levels:
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*
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* TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
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* TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
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* TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
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* TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
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* TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
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*
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* (the X axis represents the possible -5 ... 0 ... +5 dynamic
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* priority range a task can explore, a value of '1' means the
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* task is rated interactive.)
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*
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* Ie. nice +19 tasks can never get 'interactive' enough to be
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* reinserted into the active array. And only heavily CPU-hog nice -20
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* tasks will be expired. Default nice 0 tasks are somewhere between,
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* it takes some effort for them to get interactive, but it's not
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* too hard.
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*/
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#define CURRENT_BONUS(p) \
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(NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
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MAX_SLEEP_AVG)
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#define GRANULARITY (10 * HZ / 1000 ? : 1)
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#ifdef CONFIG_SMP
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#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
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(1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
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num_online_cpus())
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#else
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#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
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(1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
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#endif
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#define SCALE(v1,v1_max,v2_max) \
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(v1) * (v2_max) / (v1_max)
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#define DELTA(p) \
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(SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA)
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#define TASK_INTERACTIVE(p) \
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((p)->prio <= (p)->static_prio - DELTA(p))
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#define INTERACTIVE_SLEEP(p) \
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(JIFFIES_TO_NS(MAX_SLEEP_AVG * \
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(MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
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#define TASK_PREEMPTS_CURR(p, rq) \
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((p)->prio < (rq)->curr->prio)
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/*
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* task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
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* to time slice values: [800ms ... 100ms ... 5ms]
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*
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* The higher a thread's priority, the bigger timeslices
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* it gets during one round of execution. But even the lowest
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* priority thread gets MIN_TIMESLICE worth of execution time.
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*/
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#define SCALE_PRIO(x, prio) \
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max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE)
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static inline unsigned int task_timeslice(task_t *p)
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{
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if (p->static_prio < NICE_TO_PRIO(0))
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return SCALE_PRIO(DEF_TIMESLICE*4, p->static_prio);
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else
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return SCALE_PRIO(DEF_TIMESLICE, p->static_prio);
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}
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#define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran) \
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< (long long) (sd)->cache_hot_time)
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/*
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* These are the runqueue data structures:
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*/
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#define BITMAP_SIZE ((((MAX_PRIO+1+7)/8)+sizeof(long)-1)/sizeof(long))
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typedef struct runqueue runqueue_t;
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struct prio_array {
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unsigned int nr_active;
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unsigned long bitmap[BITMAP_SIZE];
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struct list_head queue[MAX_PRIO];
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};
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/*
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* This is the main, per-CPU runqueue data structure.
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*
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* Locking rule: those places that want to lock multiple runqueues
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* (such as the load balancing or the thread migration code), lock
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* acquire operations must be ordered by ascending &runqueue.
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*/
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struct runqueue {
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spinlock_t lock;
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/*
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* nr_running and cpu_load should be in the same cacheline because
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* remote CPUs use both these fields when doing load calculation.
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*/
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unsigned long nr_running;
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#ifdef CONFIG_SMP
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unsigned long cpu_load;
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#endif
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unsigned long long nr_switches;
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/*
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* This is part of a global counter where only the total sum
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* over all CPUs matters. A task can increase this counter on
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* one CPU and if it got migrated afterwards it may decrease
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* it on another CPU. Always updated under the runqueue lock:
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*/
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unsigned long nr_uninterruptible;
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unsigned long expired_timestamp;
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unsigned long long timestamp_last_tick;
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task_t *curr, *idle;
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struct mm_struct *prev_mm;
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prio_array_t *active, *expired, arrays[2];
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int best_expired_prio;
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atomic_t nr_iowait;
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#ifdef CONFIG_SMP
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struct sched_domain *sd;
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/* For active balancing */
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int active_balance;
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int push_cpu;
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task_t *migration_thread;
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struct list_head migration_queue;
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#endif
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#ifdef CONFIG_SCHEDSTATS
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/* latency stats */
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struct sched_info rq_sched_info;
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/* sys_sched_yield() stats */
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unsigned long yld_exp_empty;
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unsigned long yld_act_empty;
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unsigned long yld_both_empty;
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unsigned long yld_cnt;
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/* schedule() stats */
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unsigned long sched_switch;
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unsigned long sched_cnt;
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unsigned long sched_goidle;
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/* try_to_wake_up() stats */
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unsigned long ttwu_cnt;
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unsigned long ttwu_local;
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#endif
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};
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static DEFINE_PER_CPU(struct runqueue, runqueues);
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#define for_each_domain(cpu, domain) \
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for (domain = cpu_rq(cpu)->sd; domain; domain = domain->parent)
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#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
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#define this_rq() (&__get_cpu_var(runqueues))
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#define task_rq(p) cpu_rq(task_cpu(p))
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#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
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/*
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* Default context-switch locking:
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*/
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#ifndef prepare_arch_switch
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# define prepare_arch_switch(rq, next) do { } while (0)
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# define finish_arch_switch(rq, next) spin_unlock_irq(&(rq)->lock)
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# define task_running(rq, p) ((rq)->curr == (p))
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#endif
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/*
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* task_rq_lock - lock the runqueue a given task resides on and disable
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* interrupts. Note the ordering: we can safely lookup the task_rq without
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* explicitly disabling preemption.
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*/
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static inline runqueue_t *task_rq_lock(task_t *p, unsigned long *flags)
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__acquires(rq->lock)
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{
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struct runqueue *rq;
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repeat_lock_task:
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local_irq_save(*flags);
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rq = task_rq(p);
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spin_lock(&rq->lock);
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if (unlikely(rq != task_rq(p))) {
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spin_unlock_irqrestore(&rq->lock, *flags);
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goto repeat_lock_task;
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}
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return rq;
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}
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static inline void task_rq_unlock(runqueue_t *rq, unsigned long *flags)
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__releases(rq->lock)
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{
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spin_unlock_irqrestore(&rq->lock, *flags);
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}
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#ifdef CONFIG_SCHEDSTATS
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/*
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* bump this up when changing the output format or the meaning of an existing
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* format, so that tools can adapt (or abort)
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*/
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#define SCHEDSTAT_VERSION 11
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static int show_schedstat(struct seq_file *seq, void *v)
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{
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int cpu;
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seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
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seq_printf(seq, "timestamp %lu\n", jiffies);
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for_each_online_cpu(cpu) {
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runqueue_t *rq = cpu_rq(cpu);
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#ifdef CONFIG_SMP
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struct sched_domain *sd;
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int dcnt = 0;
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#endif
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/* runqueue-specific stats */
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seq_printf(seq,
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"cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
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cpu, rq->yld_both_empty,
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rq->yld_act_empty, rq->yld_exp_empty, rq->yld_cnt,
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rq->sched_switch, rq->sched_cnt, rq->sched_goidle,
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rq->ttwu_cnt, rq->ttwu_local,
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rq->rq_sched_info.cpu_time,
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rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt);
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seq_printf(seq, "\n");
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#ifdef CONFIG_SMP
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/* domain-specific stats */
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for_each_domain(cpu, sd) {
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enum idle_type itype;
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char mask_str[NR_CPUS];
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cpumask_scnprintf(mask_str, NR_CPUS, sd->span);
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seq_printf(seq, "domain%d %s", dcnt++, mask_str);
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for (itype = SCHED_IDLE; itype < MAX_IDLE_TYPES;
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itype++) {
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seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu",
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sd->lb_cnt[itype],
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sd->lb_balanced[itype],
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sd->lb_failed[itype],
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sd->lb_imbalance[itype],
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sd->lb_gained[itype],
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sd->lb_hot_gained[itype],
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sd->lb_nobusyq[itype],
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sd->lb_nobusyg[itype]);
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}
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seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu\n",
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sd->alb_cnt, sd->alb_failed, sd->alb_pushed,
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sd->sbe_pushed, sd->sbe_attempts,
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sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_move_balance);
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}
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#endif
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}
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return 0;
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}
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static int schedstat_open(struct inode *inode, struct file *file)
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{
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unsigned int size = PAGE_SIZE * (1 + num_online_cpus() / 32);
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char *buf = kmalloc(size, GFP_KERNEL);
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struct seq_file *m;
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int res;
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if (!buf)
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return -ENOMEM;
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res = single_open(file, show_schedstat, NULL);
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if (!res) {
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m = file->private_data;
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m->buf = buf;
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m->size = size;
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} else
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kfree(buf);
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return res;
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}
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struct file_operations proc_schedstat_operations = {
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.open = schedstat_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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# define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
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# define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
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#else /* !CONFIG_SCHEDSTATS */
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# define schedstat_inc(rq, field) do { } while (0)
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# define schedstat_add(rq, field, amt) do { } while (0)
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#endif
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/*
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* rq_lock - lock a given runqueue and disable interrupts.
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*/
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static inline runqueue_t *this_rq_lock(void)
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__acquires(rq->lock)
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{
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runqueue_t *rq;
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local_irq_disable();
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rq = this_rq();
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spin_lock(&rq->lock);
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return rq;
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}
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|
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#ifdef CONFIG_SCHED_SMT
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static int cpu_and_siblings_are_idle(int cpu)
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{
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int sib;
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for_each_cpu_mask(sib, cpu_sibling_map[cpu]) {
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if (idle_cpu(sib))
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continue;
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return 0;
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}
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return 1;
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}
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#else
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#define cpu_and_siblings_are_idle(A) idle_cpu(A)
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#endif
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|
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#ifdef CONFIG_SCHEDSTATS
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/*
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* Called when a process is dequeued from the active array and given
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* the cpu. We should note that with the exception of interactive
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* tasks, the expired queue will become the active queue after the active
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* queue is empty, without explicitly dequeuing and requeuing tasks in the
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* expired queue. (Interactive tasks may be requeued directly to the
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* active queue, thus delaying tasks in the expired queue from running;
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* see scheduler_tick()).
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*
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* This function is only called from sched_info_arrive(), rather than
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* dequeue_task(). Even though a task may be queued and dequeued multiple
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* times as it is shuffled about, we're really interested in knowing how
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* long it was from the *first* time it was queued to the time that it
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* finally hit a cpu.
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*/
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static inline void sched_info_dequeued(task_t *t)
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{
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t->sched_info.last_queued = 0;
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}
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|
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/*
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* Called when a task finally hits the cpu. We can now calculate how
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* long it was waiting to run. We also note when it began so that we
|
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* can keep stats on how long its timeslice is.
|
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*/
|
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static inline void sched_info_arrive(task_t *t)
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{
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unsigned long now = jiffies, diff = 0;
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struct runqueue *rq = task_rq(t);
|
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|
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if (t->sched_info.last_queued)
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diff = now - t->sched_info.last_queued;
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sched_info_dequeued(t);
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t->sched_info.run_delay += diff;
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t->sched_info.last_arrival = now;
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t->sched_info.pcnt++;
|
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|
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if (!rq)
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return;
|
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|
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rq->rq_sched_info.run_delay += diff;
|
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rq->rq_sched_info.pcnt++;
|
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}
|
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|
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/*
|
|
* Called when a process is queued into either the active or expired
|
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* array. The time is noted and later used to determine how long we
|
|
* had to wait for us to reach the cpu. Since the expired queue will
|
|
* become the active queue after active queue is empty, without dequeuing
|
|
* and requeuing any tasks, we are interested in queuing to either. It
|
|
* is unusual but not impossible for tasks to be dequeued and immediately
|
|
* requeued in the same or another array: this can happen in sched_yield(),
|
|
* set_user_nice(), and even load_balance() as it moves tasks from runqueue
|
|
* to runqueue.
|
|
*
|
|
* This function is only called from enqueue_task(), but also only updates
|
|
* the timestamp if it is already not set. It's assumed that
|
|
* sched_info_dequeued() will clear that stamp when appropriate.
|
|
*/
|
|
static inline void sched_info_queued(task_t *t)
|
|
{
|
|
if (!t->sched_info.last_queued)
|
|
t->sched_info.last_queued = jiffies;
|
|
}
|
|
|
|
/*
|
|
* Called when a process ceases being the active-running process, either
|
|
* voluntarily or involuntarily. Now we can calculate how long we ran.
|
|
*/
|
|
static inline void sched_info_depart(task_t *t)
|
|
{
|
|
struct runqueue *rq = task_rq(t);
|
|
unsigned long diff = jiffies - t->sched_info.last_arrival;
|
|
|
|
t->sched_info.cpu_time += diff;
|
|
|
|
if (rq)
|
|
rq->rq_sched_info.cpu_time += diff;
|
|
}
|
|
|
|
/*
|
|
* Called when tasks are switched involuntarily due, typically, to expiring
|
|
* their time slice. (This may also be called when switching to or from
|
|
* the idle task.) We are only called when prev != next.
|
|
*/
|
|
static inline void sched_info_switch(task_t *prev, task_t *next)
|
|
{
|
|
struct runqueue *rq = task_rq(prev);
|
|
|
|
/*
|
|
* prev now departs the cpu. It's not interesting to record
|
|
* stats about how efficient we were at scheduling the idle
|
|
* process, however.
|
|
*/
|
|
if (prev != rq->idle)
|
|
sched_info_depart(prev);
|
|
|
|
if (next != rq->idle)
|
|
sched_info_arrive(next);
|
|
}
|
|
#else
|
|
#define sched_info_queued(t) do { } while (0)
|
|
#define sched_info_switch(t, next) do { } while (0)
|
|
#endif /* CONFIG_SCHEDSTATS */
|
|
|
|
/*
|
|
* Adding/removing a task to/from a priority array:
|
|
*/
|
|
static void dequeue_task(struct task_struct *p, prio_array_t *array)
|
|
{
|
|
array->nr_active--;
|
|
list_del(&p->run_list);
|
|
if (list_empty(array->queue + p->prio))
|
|
__clear_bit(p->prio, array->bitmap);
|
|
}
|
|
|
|
static void enqueue_task(struct task_struct *p, prio_array_t *array)
|
|
{
|
|
sched_info_queued(p);
|
|
list_add_tail(&p->run_list, array->queue + p->prio);
|
|
__set_bit(p->prio, array->bitmap);
|
|
array->nr_active++;
|
|
p->array = array;
|
|
}
|
|
|
|
/*
|
|
* Put task to the end of the run list without the overhead of dequeue
|
|
* followed by enqueue.
|
|
*/
|
|
static void requeue_task(struct task_struct *p, prio_array_t *array)
|
|
{
|
|
list_move_tail(&p->run_list, array->queue + p->prio);
|
|
}
|
|
|
|
static inline void enqueue_task_head(struct task_struct *p, prio_array_t *array)
|
|
{
|
|
list_add(&p->run_list, array->queue + p->prio);
|
|
__set_bit(p->prio, array->bitmap);
|
|
array->nr_active++;
|
|
p->array = array;
|
|
}
|
|
|
|
/*
|
|
* effective_prio - return the priority that is based on the static
|
|
* priority but is modified by bonuses/penalties.
|
|
*
|
|
* We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
|
|
* into the -5 ... 0 ... +5 bonus/penalty range.
|
|
*
|
|
* We use 25% of the full 0...39 priority range so that:
|
|
*
|
|
* 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
|
|
* 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
|
|
*
|
|
* Both properties are important to certain workloads.
|
|
*/
|
|
static int effective_prio(task_t *p)
|
|
{
|
|
int bonus, prio;
|
|
|
|
if (rt_task(p))
|
|
return p->prio;
|
|
|
|
bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
|
|
|
|
prio = p->static_prio - bonus;
|
|
if (prio < MAX_RT_PRIO)
|
|
prio = MAX_RT_PRIO;
|
|
if (prio > MAX_PRIO-1)
|
|
prio = MAX_PRIO-1;
|
|
return prio;
|
|
}
|
|
|
|
/*
|
|
* __activate_task - move a task to the runqueue.
|
|
*/
|
|
static inline void __activate_task(task_t *p, runqueue_t *rq)
|
|
{
|
|
enqueue_task(p, rq->active);
|
|
rq->nr_running++;
|
|
}
|
|
|
|
/*
|
|
* __activate_idle_task - move idle task to the _front_ of runqueue.
|
|
*/
|
|
static inline void __activate_idle_task(task_t *p, runqueue_t *rq)
|
|
{
|
|
enqueue_task_head(p, rq->active);
|
|
rq->nr_running++;
|
|
}
|
|
|
|
static void recalc_task_prio(task_t *p, unsigned long long now)
|
|
{
|
|
/* Caller must always ensure 'now >= p->timestamp' */
|
|
unsigned long long __sleep_time = now - p->timestamp;
|
|
unsigned long sleep_time;
|
|
|
|
if (__sleep_time > NS_MAX_SLEEP_AVG)
|
|
sleep_time = NS_MAX_SLEEP_AVG;
|
|
else
|
|
sleep_time = (unsigned long)__sleep_time;
|
|
|
|
if (likely(sleep_time > 0)) {
|
|
/*
|
|
* User tasks that sleep a long time are categorised as
|
|
* idle and will get just interactive status to stay active &
|
|
* prevent them suddenly becoming cpu hogs and starving
|
|
* other processes.
|
|
*/
|
|
if (p->mm && p->activated != -1 &&
|
|
sleep_time > INTERACTIVE_SLEEP(p)) {
|
|
p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG -
|
|
DEF_TIMESLICE);
|
|
} else {
|
|
/*
|
|
* The lower the sleep avg a task has the more
|
|
* rapidly it will rise with sleep time.
|
|
*/
|
|
sleep_time *= (MAX_BONUS - CURRENT_BONUS(p)) ? : 1;
|
|
|
|
/*
|
|
* Tasks waking from uninterruptible sleep are
|
|
* limited in their sleep_avg rise as they
|
|
* are likely to be waiting on I/O
|
|
*/
|
|
if (p->activated == -1 && p->mm) {
|
|
if (p->sleep_avg >= INTERACTIVE_SLEEP(p))
|
|
sleep_time = 0;
|
|
else if (p->sleep_avg + sleep_time >=
|
|
INTERACTIVE_SLEEP(p)) {
|
|
p->sleep_avg = INTERACTIVE_SLEEP(p);
|
|
sleep_time = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This code gives a bonus to interactive tasks.
|
|
*
|
|
* The boost works by updating the 'average sleep time'
|
|
* value here, based on ->timestamp. The more time a
|
|
* task spends sleeping, the higher the average gets -
|
|
* and the higher the priority boost gets as well.
|
|
*/
|
|
p->sleep_avg += sleep_time;
|
|
|
|
if (p->sleep_avg > NS_MAX_SLEEP_AVG)
|
|
p->sleep_avg = NS_MAX_SLEEP_AVG;
|
|
}
|
|
}
|
|
|
|
p->prio = effective_prio(p);
|
|
}
|
|
|
|
/*
|
|
* activate_task - move a task to the runqueue and do priority recalculation
|
|
*
|
|
* Update all the scheduling statistics stuff. (sleep average
|
|
* calculation, priority modifiers, etc.)
|
|
*/
|
|
static void activate_task(task_t *p, runqueue_t *rq, int local)
|
|
{
|
|
unsigned long long now;
|
|
|
|
now = sched_clock();
|
|
#ifdef CONFIG_SMP
|
|
if (!local) {
|
|
/* Compensate for drifting sched_clock */
|
|
runqueue_t *this_rq = this_rq();
|
|
now = (now - this_rq->timestamp_last_tick)
|
|
+ rq->timestamp_last_tick;
|
|
}
|
|
#endif
|
|
|
|
recalc_task_prio(p, now);
|
|
|
|
/*
|
|
* This checks to make sure it's not an uninterruptible task
|
|
* that is now waking up.
|
|
*/
|
|
if (!p->activated) {
|
|
/*
|
|
* Tasks which were woken up by interrupts (ie. hw events)
|
|
* are most likely of interactive nature. So we give them
|
|
* the credit of extending their sleep time to the period
|
|
* of time they spend on the runqueue, waiting for execution
|
|
* on a CPU, first time around:
|
|
*/
|
|
if (in_interrupt())
|
|
p->activated = 2;
|
|
else {
|
|
/*
|
|
* Normal first-time wakeups get a credit too for
|
|
* on-runqueue time, but it will be weighted down:
|
|
*/
|
|
p->activated = 1;
|
|
}
|
|
}
|
|
p->timestamp = now;
|
|
|
|
__activate_task(p, rq);
|
|
}
|
|
|
|
/*
|
|
* deactivate_task - remove a task from the runqueue.
|
|
*/
|
|
static void deactivate_task(struct task_struct *p, runqueue_t *rq)
|
|
{
|
|
rq->nr_running--;
|
|
dequeue_task(p, p->array);
|
|
p->array = NULL;
|
|
}
|
|
|
|
/*
|
|
* resched_task - mark a task 'to be rescheduled now'.
|
|
*
|
|
* On UP this means the setting of the need_resched flag, on SMP it
|
|
* might also involve a cross-CPU call to trigger the scheduler on
|
|
* the target CPU.
|
|
*/
|
|
#ifdef CONFIG_SMP
|
|
static void resched_task(task_t *p)
|
|
{
|
|
int need_resched, nrpolling;
|
|
|
|
assert_spin_locked(&task_rq(p)->lock);
|
|
|
|
/* minimise the chance of sending an interrupt to poll_idle() */
|
|
nrpolling = test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
|
|
need_resched = test_and_set_tsk_thread_flag(p,TIF_NEED_RESCHED);
|
|
nrpolling |= test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
|
|
|
|
if (!need_resched && !nrpolling && (task_cpu(p) != smp_processor_id()))
|
|
smp_send_reschedule(task_cpu(p));
|
|
}
|
|
#else
|
|
static inline void resched_task(task_t *p)
|
|
{
|
|
set_tsk_need_resched(p);
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* task_curr - is this task currently executing on a CPU?
|
|
* @p: the task in question.
|
|
*/
|
|
inline int task_curr(const task_t *p)
|
|
{
|
|
return cpu_curr(task_cpu(p)) == p;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
enum request_type {
|
|
REQ_MOVE_TASK,
|
|
REQ_SET_DOMAIN,
|
|
};
|
|
|
|
typedef struct {
|
|
struct list_head list;
|
|
enum request_type type;
|
|
|
|
/* For REQ_MOVE_TASK */
|
|
task_t *task;
|
|
int dest_cpu;
|
|
|
|
/* For REQ_SET_DOMAIN */
|
|
struct sched_domain *sd;
|
|
|
|
struct completion done;
|
|
} migration_req_t;
|
|
|
|
/*
|
|
* The task's runqueue lock must be held.
|
|
* Returns true if you have to wait for migration thread.
|
|
*/
|
|
static int migrate_task(task_t *p, int dest_cpu, migration_req_t *req)
|
|
{
|
|
runqueue_t *rq = task_rq(p);
|
|
|
|
/*
|
|
* If the task is not on a runqueue (and not running), then
|
|
* it is sufficient to simply update the task's cpu field.
|
|
*/
|
|
if (!p->array && !task_running(rq, p)) {
|
|
set_task_cpu(p, dest_cpu);
|
|
return 0;
|
|
}
|
|
|
|
init_completion(&req->done);
|
|
req->type = REQ_MOVE_TASK;
|
|
req->task = p;
|
|
req->dest_cpu = dest_cpu;
|
|
list_add(&req->list, &rq->migration_queue);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* wait_task_inactive - wait for a thread to unschedule.
|
|
*
|
|
* The caller must ensure that the task *will* unschedule sometime soon,
|
|
* else this function might spin for a *long* time. This function can't
|
|
* be called with interrupts off, or it may introduce deadlock with
|
|
* smp_call_function() if an IPI is sent by the same process we are
|
|
* waiting to become inactive.
|
|
*/
|
|
void wait_task_inactive(task_t * p)
|
|
{
|
|
unsigned long flags;
|
|
runqueue_t *rq;
|
|
int preempted;
|
|
|
|
repeat:
|
|
rq = task_rq_lock(p, &flags);
|
|
/* Must be off runqueue entirely, not preempted. */
|
|
if (unlikely(p->array || task_running(rq, p))) {
|
|
/* If it's preempted, we yield. It could be a while. */
|
|
preempted = !task_running(rq, p);
|
|
task_rq_unlock(rq, &flags);
|
|
cpu_relax();
|
|
if (preempted)
|
|
yield();
|
|
goto repeat;
|
|
}
|
|
task_rq_unlock(rq, &flags);
|
|
}
|
|
|
|
/***
|
|
* kick_process - kick a running thread to enter/exit the kernel
|
|
* @p: the to-be-kicked thread
|
|
*
|
|
* Cause a process which is running on another CPU to enter
|
|
* kernel-mode, without any delay. (to get signals handled.)
|
|
*
|
|
* NOTE: this function doesnt have to take the runqueue lock,
|
|
* because all it wants to ensure is that the remote task enters
|
|
* the kernel. If the IPI races and the task has been migrated
|
|
* to another CPU then no harm is done and the purpose has been
|
|
* achieved as well.
|
|
*/
|
|
void kick_process(task_t *p)
|
|
{
|
|
int cpu;
|
|
|
|
preempt_disable();
|
|
cpu = task_cpu(p);
|
|
if ((cpu != smp_processor_id()) && task_curr(p))
|
|
smp_send_reschedule(cpu);
|
|
preempt_enable();
|
|
}
|
|
|
|
/*
|
|
* Return a low guess at the load of a migration-source cpu.
|
|
*
|
|
* We want to under-estimate the load of migration sources, to
|
|
* balance conservatively.
|
|
*/
|
|
static inline unsigned long source_load(int cpu)
|
|
{
|
|
runqueue_t *rq = cpu_rq(cpu);
|
|
unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
|
|
|
|
return min(rq->cpu_load, load_now);
|
|
}
|
|
|
|
/*
|
|
* Return a high guess at the load of a migration-target cpu
|
|
*/
|
|
static inline unsigned long target_load(int cpu)
|
|
{
|
|
runqueue_t *rq = cpu_rq(cpu);
|
|
unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
|
|
|
|
return max(rq->cpu_load, load_now);
|
|
}
|
|
|
|
#endif
|
|
|
|
/*
|
|
* wake_idle() will wake a task on an idle cpu if task->cpu is
|
|
* not idle and an idle cpu is available. The span of cpus to
|
|
* search starts with cpus closest then further out as needed,
|
|
* so we always favor a closer, idle cpu.
|
|
*
|
|
* Returns the CPU we should wake onto.
|
|
*/
|
|
#if defined(ARCH_HAS_SCHED_WAKE_IDLE)
|
|
static int wake_idle(int cpu, task_t *p)
|
|
{
|
|
cpumask_t tmp;
|
|
struct sched_domain *sd;
|
|
int i;
|
|
|
|
if (idle_cpu(cpu))
|
|
return cpu;
|
|
|
|
for_each_domain(cpu, sd) {
|
|
if (sd->flags & SD_WAKE_IDLE) {
|
|
cpus_and(tmp, sd->span, cpu_online_map);
|
|
cpus_and(tmp, tmp, p->cpus_allowed);
|
|
for_each_cpu_mask(i, tmp) {
|
|
if (idle_cpu(i))
|
|
return i;
|
|
}
|
|
}
|
|
else break;
|
|
}
|
|
return cpu;
|
|
}
|
|
#else
|
|
static inline int wake_idle(int cpu, task_t *p)
|
|
{
|
|
return cpu;
|
|
}
|
|
#endif
|
|
|
|
/***
|
|
* try_to_wake_up - wake up a thread
|
|
* @p: the to-be-woken-up thread
|
|
* @state: the mask of task states that can be woken
|
|
* @sync: do a synchronous wakeup?
|
|
*
|
|
* Put it on the run-queue if it's not already there. The "current"
|
|
* thread is always on the run-queue (except when the actual
|
|
* re-schedule is in progress), and as such you're allowed to do
|
|
* the simpler "current->state = TASK_RUNNING" to mark yourself
|
|
* runnable without the overhead of this.
|
|
*
|
|
* returns failure only if the task is already active.
|
|
*/
|
|
static int try_to_wake_up(task_t * p, unsigned int state, int sync)
|
|
{
|
|
int cpu, this_cpu, success = 0;
|
|
unsigned long flags;
|
|
long old_state;
|
|
runqueue_t *rq;
|
|
#ifdef CONFIG_SMP
|
|
unsigned long load, this_load;
|
|
struct sched_domain *sd;
|
|
int new_cpu;
|
|
#endif
|
|
|
|
rq = task_rq_lock(p, &flags);
|
|
old_state = p->state;
|
|
if (!(old_state & state))
|
|
goto out;
|
|
|
|
if (p->array)
|
|
goto out_running;
|
|
|
|
cpu = task_cpu(p);
|
|
this_cpu = smp_processor_id();
|
|
|
|
#ifdef CONFIG_SMP
|
|
if (unlikely(task_running(rq, p)))
|
|
goto out_activate;
|
|
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
schedstat_inc(rq, ttwu_cnt);
|
|
if (cpu == this_cpu) {
|
|
schedstat_inc(rq, ttwu_local);
|
|
} else {
|
|
for_each_domain(this_cpu, sd) {
|
|
if (cpu_isset(cpu, sd->span)) {
|
|
schedstat_inc(sd, ttwu_wake_remote);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
|
|
new_cpu = cpu;
|
|
if (cpu == this_cpu || unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
|
|
goto out_set_cpu;
|
|
|
|
load = source_load(cpu);
|
|
this_load = target_load(this_cpu);
|
|
|
|
/*
|
|
* If sync wakeup then subtract the (maximum possible) effect of
|
|
* the currently running task from the load of the current CPU:
|
|
*/
|
|
if (sync)
|
|
this_load -= SCHED_LOAD_SCALE;
|
|
|
|
/* Don't pull the task off an idle CPU to a busy one */
|
|
if (load < SCHED_LOAD_SCALE/2 && this_load > SCHED_LOAD_SCALE/2)
|
|
goto out_set_cpu;
|
|
|
|
new_cpu = this_cpu; /* Wake to this CPU if we can */
|
|
|
|
/*
|
|
* Scan domains for affine wakeup and passive balancing
|
|
* possibilities.
|
|
*/
|
|
for_each_domain(this_cpu, sd) {
|
|
unsigned int imbalance;
|
|
/*
|
|
* Start passive balancing when half the imbalance_pct
|
|
* limit is reached.
|
|
*/
|
|
imbalance = sd->imbalance_pct + (sd->imbalance_pct - 100) / 2;
|
|
|
|
if ((sd->flags & SD_WAKE_AFFINE) &&
|
|
!task_hot(p, rq->timestamp_last_tick, sd)) {
|
|
/*
|
|
* This domain has SD_WAKE_AFFINE and p is cache cold
|
|
* in this domain.
|
|
*/
|
|
if (cpu_isset(cpu, sd->span)) {
|
|
schedstat_inc(sd, ttwu_move_affine);
|
|
goto out_set_cpu;
|
|
}
|
|
} else if ((sd->flags & SD_WAKE_BALANCE) &&
|
|
imbalance*this_load <= 100*load) {
|
|
/*
|
|
* This domain has SD_WAKE_BALANCE and there is
|
|
* an imbalance.
|
|
*/
|
|
if (cpu_isset(cpu, sd->span)) {
|
|
schedstat_inc(sd, ttwu_move_balance);
|
|
goto out_set_cpu;
|
|
}
|
|
}
|
|
}
|
|
|
|
new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
|
|
out_set_cpu:
|
|
new_cpu = wake_idle(new_cpu, p);
|
|
if (new_cpu != cpu) {
|
|
set_task_cpu(p, new_cpu);
|
|
task_rq_unlock(rq, &flags);
|
|
/* might preempt at this point */
|
|
rq = task_rq_lock(p, &flags);
|
|
old_state = p->state;
|
|
if (!(old_state & state))
|
|
goto out;
|
|
if (p->array)
|
|
goto out_running;
|
|
|
|
this_cpu = smp_processor_id();
|
|
cpu = task_cpu(p);
|
|
}
|
|
|
|
out_activate:
|
|
#endif /* CONFIG_SMP */
|
|
if (old_state == TASK_UNINTERRUPTIBLE) {
|
|
rq->nr_uninterruptible--;
|
|
/*
|
|
* Tasks on involuntary sleep don't earn
|
|
* sleep_avg beyond just interactive state.
|
|
*/
|
|
p->activated = -1;
|
|
}
|
|
|
|
/*
|
|
* Sync wakeups (i.e. those types of wakeups where the waker
|
|
* has indicated that it will leave the CPU in short order)
|
|
* don't trigger a preemption, if the woken up task will run on
|
|
* this cpu. (in this case the 'I will reschedule' promise of
|
|
* the waker guarantees that the freshly woken up task is going
|
|
* to be considered on this CPU.)
|
|
*/
|
|
activate_task(p, rq, cpu == this_cpu);
|
|
if (!sync || cpu != this_cpu) {
|
|
if (TASK_PREEMPTS_CURR(p, rq))
|
|
resched_task(rq->curr);
|
|
}
|
|
success = 1;
|
|
|
|
out_running:
|
|
p->state = TASK_RUNNING;
|
|
out:
|
|
task_rq_unlock(rq, &flags);
|
|
|
|
return success;
|
|
}
|
|
|
|
int fastcall wake_up_process(task_t * p)
|
|
{
|
|
return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
|
|
TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
|
|
}
|
|
|
|
EXPORT_SYMBOL(wake_up_process);
|
|
|
|
int fastcall wake_up_state(task_t *p, unsigned int state)
|
|
{
|
|
return try_to_wake_up(p, state, 0);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static int find_idlest_cpu(struct task_struct *p, int this_cpu,
|
|
struct sched_domain *sd);
|
|
#endif
|
|
|
|
/*
|
|
* Perform scheduler related setup for a newly forked process p.
|
|
* p is forked by current.
|
|
*/
|
|
void fastcall sched_fork(task_t *p)
|
|
{
|
|
/*
|
|
* We mark the process as running here, but have not actually
|
|
* inserted it onto the runqueue yet. This guarantees that
|
|
* nobody will actually run it, and a signal or other external
|
|
* event cannot wake it up and insert it on the runqueue either.
|
|
*/
|
|
p->state = TASK_RUNNING;
|
|
INIT_LIST_HEAD(&p->run_list);
|
|
p->array = NULL;
|
|
spin_lock_init(&p->switch_lock);
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
memset(&p->sched_info, 0, sizeof(p->sched_info));
|
|
#endif
|
|
#ifdef CONFIG_PREEMPT
|
|
/*
|
|
* During context-switch we hold precisely one spinlock, which
|
|
* schedule_tail drops. (in the common case it's this_rq()->lock,
|
|
* but it also can be p->switch_lock.) So we compensate with a count
|
|
* of 1. Also, we want to start with kernel preemption disabled.
|
|
*/
|
|
p->thread_info->preempt_count = 1;
|
|
#endif
|
|
/*
|
|
* Share the timeslice between parent and child, thus the
|
|
* total amount of pending timeslices in the system doesn't change,
|
|
* resulting in more scheduling fairness.
|
|
*/
|
|
local_irq_disable();
|
|
p->time_slice = (current->time_slice + 1) >> 1;
|
|
/*
|
|
* The remainder of the first timeslice might be recovered by
|
|
* the parent if the child exits early enough.
|
|
*/
|
|
p->first_time_slice = 1;
|
|
current->time_slice >>= 1;
|
|
p->timestamp = sched_clock();
|
|
if (unlikely(!current->time_slice)) {
|
|
/*
|
|
* This case is rare, it happens when the parent has only
|
|
* a single jiffy left from its timeslice. Taking the
|
|
* runqueue lock is not a problem.
|
|
*/
|
|
current->time_slice = 1;
|
|
preempt_disable();
|
|
scheduler_tick();
|
|
local_irq_enable();
|
|
preempt_enable();
|
|
} else
|
|
local_irq_enable();
|
|
}
|
|
|
|
/*
|
|
* wake_up_new_task - wake up a newly created task for the first time.
|
|
*
|
|
* This function will do some initial scheduler statistics housekeeping
|
|
* that must be done for every newly created context, then puts the task
|
|
* on the runqueue and wakes it.
|
|
*/
|
|
void fastcall wake_up_new_task(task_t * p, unsigned long clone_flags)
|
|
{
|
|
unsigned long flags;
|
|
int this_cpu, cpu;
|
|
runqueue_t *rq, *this_rq;
|
|
|
|
rq = task_rq_lock(p, &flags);
|
|
cpu = task_cpu(p);
|
|
this_cpu = smp_processor_id();
|
|
|
|
BUG_ON(p->state != TASK_RUNNING);
|
|
|
|
/*
|
|
* We decrease the sleep average of forking parents
|
|
* and children as well, to keep max-interactive tasks
|
|
* from forking tasks that are max-interactive. The parent
|
|
* (current) is done further down, under its lock.
|
|
*/
|
|
p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
|
|
CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
|
|
|
|
p->prio = effective_prio(p);
|
|
|
|
if (likely(cpu == this_cpu)) {
|
|
if (!(clone_flags & CLONE_VM)) {
|
|
/*
|
|
* The VM isn't cloned, so we're in a good position to
|
|
* do child-runs-first in anticipation of an exec. This
|
|
* usually avoids a lot of COW overhead.
|
|
*/
|
|
if (unlikely(!current->array))
|
|
__activate_task(p, rq);
|
|
else {
|
|
p->prio = current->prio;
|
|
list_add_tail(&p->run_list, ¤t->run_list);
|
|
p->array = current->array;
|
|
p->array->nr_active++;
|
|
rq->nr_running++;
|
|
}
|
|
set_need_resched();
|
|
} else
|
|
/* Run child last */
|
|
__activate_task(p, rq);
|
|
/*
|
|
* We skip the following code due to cpu == this_cpu
|
|
*
|
|
* task_rq_unlock(rq, &flags);
|
|
* this_rq = task_rq_lock(current, &flags);
|
|
*/
|
|
this_rq = rq;
|
|
} else {
|
|
this_rq = cpu_rq(this_cpu);
|
|
|
|
/*
|
|
* Not the local CPU - must adjust timestamp. This should
|
|
* get optimised away in the !CONFIG_SMP case.
|
|
*/
|
|
p->timestamp = (p->timestamp - this_rq->timestamp_last_tick)
|
|
+ rq->timestamp_last_tick;
|
|
__activate_task(p, rq);
|
|
if (TASK_PREEMPTS_CURR(p, rq))
|
|
resched_task(rq->curr);
|
|
|
|
/*
|
|
* Parent and child are on different CPUs, now get the
|
|
* parent runqueue to update the parent's ->sleep_avg:
|
|
*/
|
|
task_rq_unlock(rq, &flags);
|
|
this_rq = task_rq_lock(current, &flags);
|
|
}
|
|
current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
|
|
PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
|
|
task_rq_unlock(this_rq, &flags);
|
|
}
|
|
|
|
/*
|
|
* Potentially available exiting-child timeslices are
|
|
* retrieved here - this way the parent does not get
|
|
* penalized for creating too many threads.
|
|
*
|
|
* (this cannot be used to 'generate' timeslices
|
|
* artificially, because any timeslice recovered here
|
|
* was given away by the parent in the first place.)
|
|
*/
|
|
void fastcall sched_exit(task_t * p)
|
|
{
|
|
unsigned long flags;
|
|
runqueue_t *rq;
|
|
|
|
/*
|
|
* If the child was a (relative-) CPU hog then decrease
|
|
* the sleep_avg of the parent as well.
|
|
*/
|
|
rq = task_rq_lock(p->parent, &flags);
|
|
if (p->first_time_slice) {
|
|
p->parent->time_slice += p->time_slice;
|
|
if (unlikely(p->parent->time_slice > task_timeslice(p)))
|
|
p->parent->time_slice = task_timeslice(p);
|
|
}
|
|
if (p->sleep_avg < p->parent->sleep_avg)
|
|
p->parent->sleep_avg = p->parent->sleep_avg /
|
|
(EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg /
|
|
(EXIT_WEIGHT + 1);
|
|
task_rq_unlock(rq, &flags);
|
|
}
|
|
|
|
/**
|
|
* finish_task_switch - clean up after a task-switch
|
|
* @prev: the thread we just switched away from.
|
|
*
|
|
* We enter this with the runqueue still locked, and finish_arch_switch()
|
|
* will unlock it along with doing any other architecture-specific cleanup
|
|
* actions.
|
|
*
|
|
* Note that we may have delayed dropping an mm in context_switch(). If
|
|
* so, we finish that here outside of the runqueue lock. (Doing it
|
|
* with the lock held can cause deadlocks; see schedule() for
|
|
* details.)
|
|
*/
|
|
static inline void finish_task_switch(task_t *prev)
|
|
__releases(rq->lock)
|
|
{
|
|
runqueue_t *rq = this_rq();
|
|
struct mm_struct *mm = rq->prev_mm;
|
|
unsigned long prev_task_flags;
|
|
|
|
rq->prev_mm = NULL;
|
|
|
|
/*
|
|
* A task struct has one reference for the use as "current".
|
|
* If a task dies, then it sets EXIT_ZOMBIE in tsk->exit_state and
|
|
* calls schedule one last time. The schedule call will never return,
|
|
* and the scheduled task must drop that reference.
|
|
* The test for EXIT_ZOMBIE must occur while the runqueue locks are
|
|
* still held, otherwise prev could be scheduled on another cpu, die
|
|
* there before we look at prev->state, and then the reference would
|
|
* be dropped twice.
|
|
* Manfred Spraul <manfred@colorfullife.com>
|
|
*/
|
|
prev_task_flags = prev->flags;
|
|
finish_arch_switch(rq, prev);
|
|
if (mm)
|
|
mmdrop(mm);
|
|
if (unlikely(prev_task_flags & PF_DEAD))
|
|
put_task_struct(prev);
|
|
}
|
|
|
|
/**
|
|
* schedule_tail - first thing a freshly forked thread must call.
|
|
* @prev: the thread we just switched away from.
|
|
*/
|
|
asmlinkage void schedule_tail(task_t *prev)
|
|
__releases(rq->lock)
|
|
{
|
|
finish_task_switch(prev);
|
|
|
|
if (current->set_child_tid)
|
|
put_user(current->pid, current->set_child_tid);
|
|
}
|
|
|
|
/*
|
|
* context_switch - switch to the new MM and the new
|
|
* thread's register state.
|
|
*/
|
|
static inline
|
|
task_t * context_switch(runqueue_t *rq, task_t *prev, task_t *next)
|
|
{
|
|
struct mm_struct *mm = next->mm;
|
|
struct mm_struct *oldmm = prev->active_mm;
|
|
|
|
if (unlikely(!mm)) {
|
|
next->active_mm = oldmm;
|
|
atomic_inc(&oldmm->mm_count);
|
|
enter_lazy_tlb(oldmm, next);
|
|
} else
|
|
switch_mm(oldmm, mm, next);
|
|
|
|
if (unlikely(!prev->mm)) {
|
|
prev->active_mm = NULL;
|
|
WARN_ON(rq->prev_mm);
|
|
rq->prev_mm = oldmm;
|
|
}
|
|
|
|
/* Here we just switch the register state and the stack. */
|
|
switch_to(prev, next, prev);
|
|
|
|
return prev;
|
|
}
|
|
|
|
/*
|
|
* nr_running, nr_uninterruptible and nr_context_switches:
|
|
*
|
|
* externally visible scheduler statistics: current number of runnable
|
|
* threads, current number of uninterruptible-sleeping threads, total
|
|
* number of context switches performed since bootup.
|
|
*/
|
|
unsigned long nr_running(void)
|
|
{
|
|
unsigned long i, sum = 0;
|
|
|
|
for_each_online_cpu(i)
|
|
sum += cpu_rq(i)->nr_running;
|
|
|
|
return sum;
|
|
}
|
|
|
|
unsigned long nr_uninterruptible(void)
|
|
{
|
|
unsigned long i, sum = 0;
|
|
|
|
for_each_cpu(i)
|
|
sum += cpu_rq(i)->nr_uninterruptible;
|
|
|
|
/*
|
|
* Since we read the counters lockless, it might be slightly
|
|
* inaccurate. Do not allow it to go below zero though:
|
|
*/
|
|
if (unlikely((long)sum < 0))
|
|
sum = 0;
|
|
|
|
return sum;
|
|
}
|
|
|
|
unsigned long long nr_context_switches(void)
|
|
{
|
|
unsigned long long i, sum = 0;
|
|
|
|
for_each_cpu(i)
|
|
sum += cpu_rq(i)->nr_switches;
|
|
|
|
return sum;
|
|
}
|
|
|
|
unsigned long nr_iowait(void)
|
|
{
|
|
unsigned long i, sum = 0;
|
|
|
|
for_each_cpu(i)
|
|
sum += atomic_read(&cpu_rq(i)->nr_iowait);
|
|
|
|
return sum;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
/*
|
|
* double_rq_lock - safely lock two runqueues
|
|
*
|
|
* Note this does not disable interrupts like task_rq_lock,
|
|
* you need to do so manually before calling.
|
|
*/
|
|
static void double_rq_lock(runqueue_t *rq1, runqueue_t *rq2)
|
|
__acquires(rq1->lock)
|
|
__acquires(rq2->lock)
|
|
{
|
|
if (rq1 == rq2) {
|
|
spin_lock(&rq1->lock);
|
|
__acquire(rq2->lock); /* Fake it out ;) */
|
|
} else {
|
|
if (rq1 < rq2) {
|
|
spin_lock(&rq1->lock);
|
|
spin_lock(&rq2->lock);
|
|
} else {
|
|
spin_lock(&rq2->lock);
|
|
spin_lock(&rq1->lock);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* double_rq_unlock - safely unlock two runqueues
|
|
*
|
|
* Note this does not restore interrupts like task_rq_unlock,
|
|
* you need to do so manually after calling.
|
|
*/
|
|
static void double_rq_unlock(runqueue_t *rq1, runqueue_t *rq2)
|
|
__releases(rq1->lock)
|
|
__releases(rq2->lock)
|
|
{
|
|
spin_unlock(&rq1->lock);
|
|
if (rq1 != rq2)
|
|
spin_unlock(&rq2->lock);
|
|
else
|
|
__release(rq2->lock);
|
|
}
|
|
|
|
/*
|
|
* double_lock_balance - lock the busiest runqueue, this_rq is locked already.
|
|
*/
|
|
static void double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest)
|
|
__releases(this_rq->lock)
|
|
__acquires(busiest->lock)
|
|
__acquires(this_rq->lock)
|
|
{
|
|
if (unlikely(!spin_trylock(&busiest->lock))) {
|
|
if (busiest < this_rq) {
|
|
spin_unlock(&this_rq->lock);
|
|
spin_lock(&busiest->lock);
|
|
spin_lock(&this_rq->lock);
|
|
} else
|
|
spin_lock(&busiest->lock);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* find_idlest_cpu - find the least busy runqueue.
|
|
*/
|
|
static int find_idlest_cpu(struct task_struct *p, int this_cpu,
|
|
struct sched_domain *sd)
|
|
{
|
|
unsigned long load, min_load, this_load;
|
|
int i, min_cpu;
|
|
cpumask_t mask;
|
|
|
|
min_cpu = UINT_MAX;
|
|
min_load = ULONG_MAX;
|
|
|
|
cpus_and(mask, sd->span, p->cpus_allowed);
|
|
|
|
for_each_cpu_mask(i, mask) {
|
|
load = target_load(i);
|
|
|
|
if (load < min_load) {
|
|
min_cpu = i;
|
|
min_load = load;
|
|
|
|
/* break out early on an idle CPU: */
|
|
if (!min_load)
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* add +1 to account for the new task */
|
|
this_load = source_load(this_cpu) + SCHED_LOAD_SCALE;
|
|
|
|
/*
|
|
* Would with the addition of the new task to the
|
|
* current CPU there be an imbalance between this
|
|
* CPU and the idlest CPU?
|
|
*
|
|
* Use half of the balancing threshold - new-context is
|
|
* a good opportunity to balance.
|
|
*/
|
|
if (min_load*(100 + (sd->imbalance_pct-100)/2) < this_load*100)
|
|
return min_cpu;
|
|
|
|
return this_cpu;
|
|
}
|
|
|
|
/*
|
|
* If dest_cpu is allowed for this process, migrate the task to it.
|
|
* This is accomplished by forcing the cpu_allowed mask to only
|
|
* allow dest_cpu, which will force the cpu onto dest_cpu. Then
|
|
* the cpu_allowed mask is restored.
|
|
*/
|
|
static void sched_migrate_task(task_t *p, int dest_cpu)
|
|
{
|
|
migration_req_t req;
|
|
runqueue_t *rq;
|
|
unsigned long flags;
|
|
|
|
rq = task_rq_lock(p, &flags);
|
|
if (!cpu_isset(dest_cpu, p->cpus_allowed)
|
|
|| unlikely(cpu_is_offline(dest_cpu)))
|
|
goto out;
|
|
|
|
/* force the process onto the specified CPU */
|
|
if (migrate_task(p, dest_cpu, &req)) {
|
|
/* Need to wait for migration thread (might exit: take ref). */
|
|
struct task_struct *mt = rq->migration_thread;
|
|
get_task_struct(mt);
|
|
task_rq_unlock(rq, &flags);
|
|
wake_up_process(mt);
|
|
put_task_struct(mt);
|
|
wait_for_completion(&req.done);
|
|
return;
|
|
}
|
|
out:
|
|
task_rq_unlock(rq, &flags);
|
|
}
|
|
|
|
/*
|
|
* sched_exec(): find the highest-level, exec-balance-capable
|
|
* domain and try to migrate the task to the least loaded CPU.
|
|
*
|
|
* execve() is a valuable balancing opportunity, because at this point
|
|
* the task has the smallest effective memory and cache footprint.
|
|
*/
|
|
void sched_exec(void)
|
|
{
|
|
struct sched_domain *tmp, *sd = NULL;
|
|
int new_cpu, this_cpu = get_cpu();
|
|
|
|
/* Prefer the current CPU if there's only this task running */
|
|
if (this_rq()->nr_running <= 1)
|
|
goto out;
|
|
|
|
for_each_domain(this_cpu, tmp)
|
|
if (tmp->flags & SD_BALANCE_EXEC)
|
|
sd = tmp;
|
|
|
|
if (sd) {
|
|
schedstat_inc(sd, sbe_attempts);
|
|
new_cpu = find_idlest_cpu(current, this_cpu, sd);
|
|
if (new_cpu != this_cpu) {
|
|
schedstat_inc(sd, sbe_pushed);
|
|
put_cpu();
|
|
sched_migrate_task(current, new_cpu);
|
|
return;
|
|
}
|
|
}
|
|
out:
|
|
put_cpu();
|
|
}
|
|
|
|
/*
|
|
* pull_task - move a task from a remote runqueue to the local runqueue.
|
|
* Both runqueues must be locked.
|
|
*/
|
|
static inline
|
|
void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p,
|
|
runqueue_t *this_rq, prio_array_t *this_array, int this_cpu)
|
|
{
|
|
dequeue_task(p, src_array);
|
|
src_rq->nr_running--;
|
|
set_task_cpu(p, this_cpu);
|
|
this_rq->nr_running++;
|
|
enqueue_task(p, this_array);
|
|
p->timestamp = (p->timestamp - src_rq->timestamp_last_tick)
|
|
+ this_rq->timestamp_last_tick;
|
|
/*
|
|
* Note that idle threads have a prio of MAX_PRIO, for this test
|
|
* to be always true for them.
|
|
*/
|
|
if (TASK_PREEMPTS_CURR(p, this_rq))
|
|
resched_task(this_rq->curr);
|
|
}
|
|
|
|
/*
|
|
* can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
|
|
*/
|
|
static inline
|
|
int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
|
|
struct sched_domain *sd, enum idle_type idle)
|
|
{
|
|
/*
|
|
* We do not migrate tasks that are:
|
|
* 1) running (obviously), or
|
|
* 2) cannot be migrated to this CPU due to cpus_allowed, or
|
|
* 3) are cache-hot on their current CPU.
|
|
*/
|
|
if (task_running(rq, p))
|
|
return 0;
|
|
if (!cpu_isset(this_cpu, p->cpus_allowed))
|
|
return 0;
|
|
|
|
/*
|
|
* Aggressive migration if:
|
|
* 1) the [whole] cpu is idle, or
|
|
* 2) too many balance attempts have failed.
|
|
*/
|
|
|
|
if (cpu_and_siblings_are_idle(this_cpu) || \
|
|
sd->nr_balance_failed > sd->cache_nice_tries)
|
|
return 1;
|
|
|
|
if (task_hot(p, rq->timestamp_last_tick, sd))
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
|
|
* as part of a balancing operation within "domain". Returns the number of
|
|
* tasks moved.
|
|
*
|
|
* Called with both runqueues locked.
|
|
*/
|
|
static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest,
|
|
unsigned long max_nr_move, struct sched_domain *sd,
|
|
enum idle_type idle)
|
|
{
|
|
prio_array_t *array, *dst_array;
|
|
struct list_head *head, *curr;
|
|
int idx, pulled = 0;
|
|
task_t *tmp;
|
|
|
|
if (max_nr_move <= 0 || busiest->nr_running <= 1)
|
|
goto out;
|
|
|
|
/*
|
|
* We first consider expired tasks. Those will likely not be
|
|
* executed in the near future, and they are most likely to
|
|
* be cache-cold, thus switching CPUs has the least effect
|
|
* on them.
|
|
*/
|
|
if (busiest->expired->nr_active) {
|
|
array = busiest->expired;
|
|
dst_array = this_rq->expired;
|
|
} else {
|
|
array = busiest->active;
|
|
dst_array = this_rq->active;
|
|
}
|
|
|
|
new_array:
|
|
/* Start searching at priority 0: */
|
|
idx = 0;
|
|
skip_bitmap:
|
|
if (!idx)
|
|
idx = sched_find_first_bit(array->bitmap);
|
|
else
|
|
idx = find_next_bit(array->bitmap, MAX_PRIO, idx);
|
|
if (idx >= MAX_PRIO) {
|
|
if (array == busiest->expired && busiest->active->nr_active) {
|
|
array = busiest->active;
|
|
dst_array = this_rq->active;
|
|
goto new_array;
|
|
}
|
|
goto out;
|
|
}
|
|
|
|
head = array->queue + idx;
|
|
curr = head->prev;
|
|
skip_queue:
|
|
tmp = list_entry(curr, task_t, run_list);
|
|
|
|
curr = curr->prev;
|
|
|
|
if (!can_migrate_task(tmp, busiest, this_cpu, sd, idle)) {
|
|
if (curr != head)
|
|
goto skip_queue;
|
|
idx++;
|
|
goto skip_bitmap;
|
|
}
|
|
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
if (task_hot(tmp, busiest->timestamp_last_tick, sd))
|
|
schedstat_inc(sd, lb_hot_gained[idle]);
|
|
#endif
|
|
|
|
pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
|
|
pulled++;
|
|
|
|
/* We only want to steal up to the prescribed number of tasks. */
|
|
if (pulled < max_nr_move) {
|
|
if (curr != head)
|
|
goto skip_queue;
|
|
idx++;
|
|
goto skip_bitmap;
|
|
}
|
|
out:
|
|
/*
|
|
* Right now, this is the only place pull_task() is called,
|
|
* so we can safely collect pull_task() stats here rather than
|
|
* inside pull_task().
|
|
*/
|
|
schedstat_add(sd, lb_gained[idle], pulled);
|
|
return pulled;
|
|
}
|
|
|
|
/*
|
|
* find_busiest_group finds and returns the busiest CPU group within the
|
|
* domain. It calculates and returns the number of tasks which should be
|
|
* moved to restore balance via the imbalance parameter.
|
|
*/
|
|
static struct sched_group *
|
|
find_busiest_group(struct sched_domain *sd, int this_cpu,
|
|
unsigned long *imbalance, enum idle_type idle)
|
|
{
|
|
struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
|
|
unsigned long max_load, avg_load, total_load, this_load, total_pwr;
|
|
|
|
max_load = this_load = total_load = total_pwr = 0;
|
|
|
|
do {
|
|
unsigned long load;
|
|
int local_group;
|
|
int i;
|
|
|
|
local_group = cpu_isset(this_cpu, group->cpumask);
|
|
|
|
/* Tally up the load of all CPUs in the group */
|
|
avg_load = 0;
|
|
|
|
for_each_cpu_mask(i, group->cpumask) {
|
|
/* Bias balancing toward cpus of our domain */
|
|
if (local_group)
|
|
load = target_load(i);
|
|
else
|
|
load = source_load(i);
|
|
|
|
avg_load += load;
|
|
}
|
|
|
|
total_load += avg_load;
|
|
total_pwr += group->cpu_power;
|
|
|
|
/* Adjust by relative CPU power of the group */
|
|
avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
|
|
|
|
if (local_group) {
|
|
this_load = avg_load;
|
|
this = group;
|
|
goto nextgroup;
|
|
} else if (avg_load > max_load) {
|
|
max_load = avg_load;
|
|
busiest = group;
|
|
}
|
|
nextgroup:
|
|
group = group->next;
|
|
} while (group != sd->groups);
|
|
|
|
if (!busiest || this_load >= max_load)
|
|
goto out_balanced;
|
|
|
|
avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
|
|
|
|
if (this_load >= avg_load ||
|
|
100*max_load <= sd->imbalance_pct*this_load)
|
|
goto out_balanced;
|
|
|
|
/*
|
|
* We're trying to get all the cpus to the average_load, so we don't
|
|
* want to push ourselves above the average load, nor do we wish to
|
|
* reduce the max loaded cpu below the average load, as either of these
|
|
* actions would just result in more rebalancing later, and ping-pong
|
|
* tasks around. Thus we look for the minimum possible imbalance.
|
|
* Negative imbalances (*we* are more loaded than anyone else) will
|
|
* be counted as no imbalance for these purposes -- we can't fix that
|
|
* by pulling tasks to us. Be careful of negative numbers as they'll
|
|
* appear as very large values with unsigned longs.
|
|
*/
|
|
/* How much load to actually move to equalise the imbalance */
|
|
*imbalance = min((max_load - avg_load) * busiest->cpu_power,
|
|
(avg_load - this_load) * this->cpu_power)
|
|
/ SCHED_LOAD_SCALE;
|
|
|
|
if (*imbalance < SCHED_LOAD_SCALE) {
|
|
unsigned long pwr_now = 0, pwr_move = 0;
|
|
unsigned long tmp;
|
|
|
|
if (max_load - this_load >= SCHED_LOAD_SCALE*2) {
|
|
*imbalance = 1;
|
|
return busiest;
|
|
}
|
|
|
|
/*
|
|
* OK, we don't have enough imbalance to justify moving tasks,
|
|
* however we may be able to increase total CPU power used by
|
|
* moving them.
|
|
*/
|
|
|
|
pwr_now += busiest->cpu_power*min(SCHED_LOAD_SCALE, max_load);
|
|
pwr_now += this->cpu_power*min(SCHED_LOAD_SCALE, this_load);
|
|
pwr_now /= SCHED_LOAD_SCALE;
|
|
|
|
/* Amount of load we'd subtract */
|
|
tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/busiest->cpu_power;
|
|
if (max_load > tmp)
|
|
pwr_move += busiest->cpu_power*min(SCHED_LOAD_SCALE,
|
|
max_load - tmp);
|
|
|
|
/* Amount of load we'd add */
|
|
if (max_load*busiest->cpu_power <
|
|
SCHED_LOAD_SCALE*SCHED_LOAD_SCALE)
|
|
tmp = max_load*busiest->cpu_power/this->cpu_power;
|
|
else
|
|
tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/this->cpu_power;
|
|
pwr_move += this->cpu_power*min(SCHED_LOAD_SCALE, this_load + tmp);
|
|
pwr_move /= SCHED_LOAD_SCALE;
|
|
|
|
/* Move if we gain throughput */
|
|
if (pwr_move <= pwr_now)
|
|
goto out_balanced;
|
|
|
|
*imbalance = 1;
|
|
return busiest;
|
|
}
|
|
|
|
/* Get rid of the scaling factor, rounding down as we divide */
|
|
*imbalance = *imbalance / SCHED_LOAD_SCALE;
|
|
|
|
return busiest;
|
|
|
|
out_balanced:
|
|
if (busiest && (idle == NEWLY_IDLE ||
|
|
(idle == SCHED_IDLE && max_load > SCHED_LOAD_SCALE)) ) {
|
|
*imbalance = 1;
|
|
return busiest;
|
|
}
|
|
|
|
*imbalance = 0;
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* find_busiest_queue - find the busiest runqueue among the cpus in group.
|
|
*/
|
|
static runqueue_t *find_busiest_queue(struct sched_group *group)
|
|
{
|
|
unsigned long load, max_load = 0;
|
|
runqueue_t *busiest = NULL;
|
|
int i;
|
|
|
|
for_each_cpu_mask(i, group->cpumask) {
|
|
load = source_load(i);
|
|
|
|
if (load > max_load) {
|
|
max_load = load;
|
|
busiest = cpu_rq(i);
|
|
}
|
|
}
|
|
|
|
return busiest;
|
|
}
|
|
|
|
/*
|
|
* Check this_cpu to ensure it is balanced within domain. Attempt to move
|
|
* tasks if there is an imbalance.
|
|
*
|
|
* Called with this_rq unlocked.
|
|
*/
|
|
static int load_balance(int this_cpu, runqueue_t *this_rq,
|
|
struct sched_domain *sd, enum idle_type idle)
|
|
{
|
|
struct sched_group *group;
|
|
runqueue_t *busiest;
|
|
unsigned long imbalance;
|
|
int nr_moved;
|
|
|
|
spin_lock(&this_rq->lock);
|
|
schedstat_inc(sd, lb_cnt[idle]);
|
|
|
|
group = find_busiest_group(sd, this_cpu, &imbalance, idle);
|
|
if (!group) {
|
|
schedstat_inc(sd, lb_nobusyg[idle]);
|
|
goto out_balanced;
|
|
}
|
|
|
|
busiest = find_busiest_queue(group);
|
|
if (!busiest) {
|
|
schedstat_inc(sd, lb_nobusyq[idle]);
|
|
goto out_balanced;
|
|
}
|
|
|
|
/*
|
|
* This should be "impossible", but since load
|
|
* balancing is inherently racy and statistical,
|
|
* it could happen in theory.
|
|
*/
|
|
if (unlikely(busiest == this_rq)) {
|
|
WARN_ON(1);
|
|
goto out_balanced;
|
|
}
|
|
|
|
schedstat_add(sd, lb_imbalance[idle], imbalance);
|
|
|
|
nr_moved = 0;
|
|
if (busiest->nr_running > 1) {
|
|
/*
|
|
* Attempt to move tasks. If find_busiest_group has found
|
|
* an imbalance but busiest->nr_running <= 1, the group is
|
|
* still unbalanced. nr_moved simply stays zero, so it is
|
|
* correctly treated as an imbalance.
|
|
*/
|
|
double_lock_balance(this_rq, busiest);
|
|
nr_moved = move_tasks(this_rq, this_cpu, busiest,
|
|
imbalance, sd, idle);
|
|
spin_unlock(&busiest->lock);
|
|
}
|
|
spin_unlock(&this_rq->lock);
|
|
|
|
if (!nr_moved) {
|
|
schedstat_inc(sd, lb_failed[idle]);
|
|
sd->nr_balance_failed++;
|
|
|
|
if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
|
|
int wake = 0;
|
|
|
|
spin_lock(&busiest->lock);
|
|
if (!busiest->active_balance) {
|
|
busiest->active_balance = 1;
|
|
busiest->push_cpu = this_cpu;
|
|
wake = 1;
|
|
}
|
|
spin_unlock(&busiest->lock);
|
|
if (wake)
|
|
wake_up_process(busiest->migration_thread);
|
|
|
|
/*
|
|
* We've kicked active balancing, reset the failure
|
|
* counter.
|
|
*/
|
|
sd->nr_balance_failed = sd->cache_nice_tries;
|
|
}
|
|
|
|
/*
|
|
* We were unbalanced, but unsuccessful in move_tasks(),
|
|
* so bump the balance_interval to lessen the lock contention.
|
|
*/
|
|
if (sd->balance_interval < sd->max_interval)
|
|
sd->balance_interval++;
|
|
} else {
|
|
sd->nr_balance_failed = 0;
|
|
|
|
/* We were unbalanced, so reset the balancing interval */
|
|
sd->balance_interval = sd->min_interval;
|
|
}
|
|
|
|
return nr_moved;
|
|
|
|
out_balanced:
|
|
spin_unlock(&this_rq->lock);
|
|
|
|
schedstat_inc(sd, lb_balanced[idle]);
|
|
|
|
/* tune up the balancing interval */
|
|
if (sd->balance_interval < sd->max_interval)
|
|
sd->balance_interval *= 2;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Check this_cpu to ensure it is balanced within domain. Attempt to move
|
|
* tasks if there is an imbalance.
|
|
*
|
|
* Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
|
|
* this_rq is locked.
|
|
*/
|
|
static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
|
|
struct sched_domain *sd)
|
|
{
|
|
struct sched_group *group;
|
|
runqueue_t *busiest = NULL;
|
|
unsigned long imbalance;
|
|
int nr_moved = 0;
|
|
|
|
schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);
|
|
group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE);
|
|
if (!group) {
|
|
schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
|
|
schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]);
|
|
goto out;
|
|
}
|
|
|
|
busiest = find_busiest_queue(group);
|
|
if (!busiest || busiest == this_rq) {
|
|
schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
|
|
schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
|
|
goto out;
|
|
}
|
|
|
|
/* Attempt to move tasks */
|
|
double_lock_balance(this_rq, busiest);
|
|
|
|
schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
|
|
nr_moved = move_tasks(this_rq, this_cpu, busiest,
|
|
imbalance, sd, NEWLY_IDLE);
|
|
if (!nr_moved)
|
|
schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
|
|
|
|
spin_unlock(&busiest->lock);
|
|
|
|
out:
|
|
return nr_moved;
|
|
}
|
|
|
|
/*
|
|
* idle_balance is called by schedule() if this_cpu is about to become
|
|
* idle. Attempts to pull tasks from other CPUs.
|
|
*/
|
|
static inline void idle_balance(int this_cpu, runqueue_t *this_rq)
|
|
{
|
|
struct sched_domain *sd;
|
|
|
|
for_each_domain(this_cpu, sd) {
|
|
if (sd->flags & SD_BALANCE_NEWIDLE) {
|
|
if (load_balance_newidle(this_cpu, this_rq, sd)) {
|
|
/* We've pulled tasks over so stop searching */
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* active_load_balance is run by migration threads. It pushes running tasks
|
|
* off the busiest CPU onto idle CPUs. It requires at least 1 task to be
|
|
* running on each physical CPU where possible, and avoids physical /
|
|
* logical imbalances.
|
|
*
|
|
* Called with busiest_rq locked.
|
|
*/
|
|
static void active_load_balance(runqueue_t *busiest_rq, int busiest_cpu)
|
|
{
|
|
struct sched_domain *sd;
|
|
struct sched_group *cpu_group;
|
|
runqueue_t *target_rq;
|
|
cpumask_t visited_cpus;
|
|
int cpu;
|
|
|
|
/*
|
|
* Search for suitable CPUs to push tasks to in successively higher
|
|
* domains with SD_LOAD_BALANCE set.
|
|
*/
|
|
visited_cpus = CPU_MASK_NONE;
|
|
for_each_domain(busiest_cpu, sd) {
|
|
if (!(sd->flags & SD_LOAD_BALANCE))
|
|
/* no more domains to search */
|
|
break;
|
|
|
|
schedstat_inc(sd, alb_cnt);
|
|
|
|
cpu_group = sd->groups;
|
|
do {
|
|
for_each_cpu_mask(cpu, cpu_group->cpumask) {
|
|
if (busiest_rq->nr_running <= 1)
|
|
/* no more tasks left to move */
|
|
return;
|
|
if (cpu_isset(cpu, visited_cpus))
|
|
continue;
|
|
cpu_set(cpu, visited_cpus);
|
|
if (!cpu_and_siblings_are_idle(cpu) || cpu == busiest_cpu)
|
|
continue;
|
|
|
|
target_rq = cpu_rq(cpu);
|
|
/*
|
|
* This condition is "impossible", if it occurs
|
|
* we need to fix it. Originally reported by
|
|
* Bjorn Helgaas on a 128-cpu setup.
|
|
*/
|
|
BUG_ON(busiest_rq == target_rq);
|
|
|
|
/* move a task from busiest_rq to target_rq */
|
|
double_lock_balance(busiest_rq, target_rq);
|
|
if (move_tasks(target_rq, cpu, busiest_rq,
|
|
1, sd, SCHED_IDLE)) {
|
|
schedstat_inc(sd, alb_pushed);
|
|
} else {
|
|
schedstat_inc(sd, alb_failed);
|
|
}
|
|
spin_unlock(&target_rq->lock);
|
|
}
|
|
cpu_group = cpu_group->next;
|
|
} while (cpu_group != sd->groups);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* rebalance_tick will get called every timer tick, on every CPU.
|
|
*
|
|
* It checks each scheduling domain to see if it is due to be balanced,
|
|
* and initiates a balancing operation if so.
|
|
*
|
|
* Balancing parameters are set up in arch_init_sched_domains.
|
|
*/
|
|
|
|
/* Don't have all balancing operations going off at once */
|
|
#define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
|
|
|
|
static void rebalance_tick(int this_cpu, runqueue_t *this_rq,
|
|
enum idle_type idle)
|
|
{
|
|
unsigned long old_load, this_load;
|
|
unsigned long j = jiffies + CPU_OFFSET(this_cpu);
|
|
struct sched_domain *sd;
|
|
|
|
/* Update our load */
|
|
old_load = this_rq->cpu_load;
|
|
this_load = this_rq->nr_running * SCHED_LOAD_SCALE;
|
|
/*
|
|
* Round up the averaging division if load is increasing. This
|
|
* prevents us from getting stuck on 9 if the load is 10, for
|
|
* example.
|
|
*/
|
|
if (this_load > old_load)
|
|
old_load++;
|
|
this_rq->cpu_load = (old_load + this_load) / 2;
|
|
|
|
for_each_domain(this_cpu, sd) {
|
|
unsigned long interval;
|
|
|
|
if (!(sd->flags & SD_LOAD_BALANCE))
|
|
continue;
|
|
|
|
interval = sd->balance_interval;
|
|
if (idle != SCHED_IDLE)
|
|
interval *= sd->busy_factor;
|
|
|
|
/* scale ms to jiffies */
|
|
interval = msecs_to_jiffies(interval);
|
|
if (unlikely(!interval))
|
|
interval = 1;
|
|
|
|
if (j - sd->last_balance >= interval) {
|
|
if (load_balance(this_cpu, this_rq, sd, idle)) {
|
|
/* We've pulled tasks over so no longer idle */
|
|
idle = NOT_IDLE;
|
|
}
|
|
sd->last_balance += interval;
|
|
}
|
|
}
|
|
}
|
|
#else
|
|
/*
|
|
* on UP we do not need to balance between CPUs:
|
|
*/
|
|
static inline void rebalance_tick(int cpu, runqueue_t *rq, enum idle_type idle)
|
|
{
|
|
}
|
|
static inline void idle_balance(int cpu, runqueue_t *rq)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static inline int wake_priority_sleeper(runqueue_t *rq)
|
|
{
|
|
int ret = 0;
|
|
#ifdef CONFIG_SCHED_SMT
|
|
spin_lock(&rq->lock);
|
|
/*
|
|
* If an SMT sibling task has been put to sleep for priority
|
|
* reasons reschedule the idle task to see if it can now run.
|
|
*/
|
|
if (rq->nr_running) {
|
|
resched_task(rq->idle);
|
|
ret = 1;
|
|
}
|
|
spin_unlock(&rq->lock);
|
|
#endif
|
|
return ret;
|
|
}
|
|
|
|
DEFINE_PER_CPU(struct kernel_stat, kstat);
|
|
|
|
EXPORT_PER_CPU_SYMBOL(kstat);
|
|
|
|
/*
|
|
* This is called on clock ticks and on context switches.
|
|
* Bank in p->sched_time the ns elapsed since the last tick or switch.
|
|
*/
|
|
static inline void update_cpu_clock(task_t *p, runqueue_t *rq,
|
|
unsigned long long now)
|
|
{
|
|
unsigned long long last = max(p->timestamp, rq->timestamp_last_tick);
|
|
p->sched_time += now - last;
|
|
}
|
|
|
|
/*
|
|
* Return current->sched_time plus any more ns on the sched_clock
|
|
* that have not yet been banked.
|
|
*/
|
|
unsigned long long current_sched_time(const task_t *tsk)
|
|
{
|
|
unsigned long long ns;
|
|
unsigned long flags;
|
|
local_irq_save(flags);
|
|
ns = max(tsk->timestamp, task_rq(tsk)->timestamp_last_tick);
|
|
ns = tsk->sched_time + (sched_clock() - ns);
|
|
local_irq_restore(flags);
|
|
return ns;
|
|
}
|
|
|
|
/*
|
|
* We place interactive tasks back into the active array, if possible.
|
|
*
|
|
* To guarantee that this does not starve expired tasks we ignore the
|
|
* interactivity of a task if the first expired task had to wait more
|
|
* than a 'reasonable' amount of time. This deadline timeout is
|
|
* load-dependent, as the frequency of array switched decreases with
|
|
* increasing number of running tasks. We also ignore the interactivity
|
|
* if a better static_prio task has expired:
|
|
*/
|
|
#define EXPIRED_STARVING(rq) \
|
|
((STARVATION_LIMIT && ((rq)->expired_timestamp && \
|
|
(jiffies - (rq)->expired_timestamp >= \
|
|
STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \
|
|
((rq)->curr->static_prio > (rq)->best_expired_prio))
|
|
|
|
/*
|
|
* Account user cpu time to a process.
|
|
* @p: the process that the cpu time gets accounted to
|
|
* @hardirq_offset: the offset to subtract from hardirq_count()
|
|
* @cputime: the cpu time spent in user space since the last update
|
|
*/
|
|
void account_user_time(struct task_struct *p, cputime_t cputime)
|
|
{
|
|
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
|
|
cputime64_t tmp;
|
|
|
|
p->utime = cputime_add(p->utime, cputime);
|
|
|
|
/* Add user time to cpustat. */
|
|
tmp = cputime_to_cputime64(cputime);
|
|
if (TASK_NICE(p) > 0)
|
|
cpustat->nice = cputime64_add(cpustat->nice, tmp);
|
|
else
|
|
cpustat->user = cputime64_add(cpustat->user, tmp);
|
|
}
|
|
|
|
/*
|
|
* Account system cpu time to a process.
|
|
* @p: the process that the cpu time gets accounted to
|
|
* @hardirq_offset: the offset to subtract from hardirq_count()
|
|
* @cputime: the cpu time spent in kernel space since the last update
|
|
*/
|
|
void account_system_time(struct task_struct *p, int hardirq_offset,
|
|
cputime_t cputime)
|
|
{
|
|
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
|
|
runqueue_t *rq = this_rq();
|
|
cputime64_t tmp;
|
|
|
|
p->stime = cputime_add(p->stime, cputime);
|
|
|
|
/* Add system time to cpustat. */
|
|
tmp = cputime_to_cputime64(cputime);
|
|
if (hardirq_count() - hardirq_offset)
|
|
cpustat->irq = cputime64_add(cpustat->irq, tmp);
|
|
else if (softirq_count())
|
|
cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
|
|
else if (p != rq->idle)
|
|
cpustat->system = cputime64_add(cpustat->system, tmp);
|
|
else if (atomic_read(&rq->nr_iowait) > 0)
|
|
cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
|
|
else
|
|
cpustat->idle = cputime64_add(cpustat->idle, tmp);
|
|
/* Account for system time used */
|
|
acct_update_integrals(p);
|
|
/* Update rss highwater mark */
|
|
update_mem_hiwater(p);
|
|
}
|
|
|
|
/*
|
|
* Account for involuntary wait time.
|
|
* @p: the process from which the cpu time has been stolen
|
|
* @steal: the cpu time spent in involuntary wait
|
|
*/
|
|
void account_steal_time(struct task_struct *p, cputime_t steal)
|
|
{
|
|
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
|
|
cputime64_t tmp = cputime_to_cputime64(steal);
|
|
runqueue_t *rq = this_rq();
|
|
|
|
if (p == rq->idle) {
|
|
p->stime = cputime_add(p->stime, steal);
|
|
if (atomic_read(&rq->nr_iowait) > 0)
|
|
cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
|
|
else
|
|
cpustat->idle = cputime64_add(cpustat->idle, tmp);
|
|
} else
|
|
cpustat->steal = cputime64_add(cpustat->steal, tmp);
|
|
}
|
|
|
|
/*
|
|
* This function gets called by the timer code, with HZ frequency.
|
|
* We call it with interrupts disabled.
|
|
*
|
|
* It also gets called by the fork code, when changing the parent's
|
|
* timeslices.
|
|
*/
|
|
void scheduler_tick(void)
|
|
{
|
|
int cpu = smp_processor_id();
|
|
runqueue_t *rq = this_rq();
|
|
task_t *p = current;
|
|
unsigned long long now = sched_clock();
|
|
|
|
update_cpu_clock(p, rq, now);
|
|
|
|
rq->timestamp_last_tick = now;
|
|
|
|
if (p == rq->idle) {
|
|
if (wake_priority_sleeper(rq))
|
|
goto out;
|
|
rebalance_tick(cpu, rq, SCHED_IDLE);
|
|
return;
|
|
}
|
|
|
|
/* Task might have expired already, but not scheduled off yet */
|
|
if (p->array != rq->active) {
|
|
set_tsk_need_resched(p);
|
|
goto out;
|
|
}
|
|
spin_lock(&rq->lock);
|
|
/*
|
|
* The task was running during this tick - update the
|
|
* time slice counter. Note: we do not update a thread's
|
|
* priority until it either goes to sleep or uses up its
|
|
* timeslice. This makes it possible for interactive tasks
|
|
* to use up their timeslices at their highest priority levels.
|
|
*/
|
|
if (rt_task(p)) {
|
|
/*
|
|
* RR tasks need a special form of timeslice management.
|
|
* FIFO tasks have no timeslices.
|
|
*/
|
|
if ((p->policy == SCHED_RR) && !--p->time_slice) {
|
|
p->time_slice = task_timeslice(p);
|
|
p->first_time_slice = 0;
|
|
set_tsk_need_resched(p);
|
|
|
|
/* put it at the end of the queue: */
|
|
requeue_task(p, rq->active);
|
|
}
|
|
goto out_unlock;
|
|
}
|
|
if (!--p->time_slice) {
|
|
dequeue_task(p, rq->active);
|
|
set_tsk_need_resched(p);
|
|
p->prio = effective_prio(p);
|
|
p->time_slice = task_timeslice(p);
|
|
p->first_time_slice = 0;
|
|
|
|
if (!rq->expired_timestamp)
|
|
rq->expired_timestamp = jiffies;
|
|
if (!TASK_INTERACTIVE(p) || EXPIRED_STARVING(rq)) {
|
|
enqueue_task(p, rq->expired);
|
|
if (p->static_prio < rq->best_expired_prio)
|
|
rq->best_expired_prio = p->static_prio;
|
|
} else
|
|
enqueue_task(p, rq->active);
|
|
} else {
|
|
/*
|
|
* Prevent a too long timeslice allowing a task to monopolize
|
|
* the CPU. We do this by splitting up the timeslice into
|
|
* smaller pieces.
|
|
*
|
|
* Note: this does not mean the task's timeslices expire or
|
|
* get lost in any way, they just might be preempted by
|
|
* another task of equal priority. (one with higher
|
|
* priority would have preempted this task already.) We
|
|
* requeue this task to the end of the list on this priority
|
|
* level, which is in essence a round-robin of tasks with
|
|
* equal priority.
|
|
*
|
|
* This only applies to tasks in the interactive
|
|
* delta range with at least TIMESLICE_GRANULARITY to requeue.
|
|
*/
|
|
if (TASK_INTERACTIVE(p) && !((task_timeslice(p) -
|
|
p->time_slice) % TIMESLICE_GRANULARITY(p)) &&
|
|
(p->time_slice >= TIMESLICE_GRANULARITY(p)) &&
|
|
(p->array == rq->active)) {
|
|
|
|
requeue_task(p, rq->active);
|
|
set_tsk_need_resched(p);
|
|
}
|
|
}
|
|
out_unlock:
|
|
spin_unlock(&rq->lock);
|
|
out:
|
|
rebalance_tick(cpu, rq, NOT_IDLE);
|
|
}
|
|
|
|
#ifdef CONFIG_SCHED_SMT
|
|
static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
|
|
{
|
|
struct sched_domain *sd = this_rq->sd;
|
|
cpumask_t sibling_map;
|
|
int i;
|
|
|
|
if (!(sd->flags & SD_SHARE_CPUPOWER))
|
|
return;
|
|
|
|
/*
|
|
* Unlock the current runqueue because we have to lock in
|
|
* CPU order to avoid deadlocks. Caller knows that we might
|
|
* unlock. We keep IRQs disabled.
|
|
*/
|
|
spin_unlock(&this_rq->lock);
|
|
|
|
sibling_map = sd->span;
|
|
|
|
for_each_cpu_mask(i, sibling_map)
|
|
spin_lock(&cpu_rq(i)->lock);
|
|
/*
|
|
* We clear this CPU from the mask. This both simplifies the
|
|
* inner loop and keps this_rq locked when we exit:
|
|
*/
|
|
cpu_clear(this_cpu, sibling_map);
|
|
|
|
for_each_cpu_mask(i, sibling_map) {
|
|
runqueue_t *smt_rq = cpu_rq(i);
|
|
|
|
/*
|
|
* If an SMT sibling task is sleeping due to priority
|
|
* reasons wake it up now.
|
|
*/
|
|
if (smt_rq->curr == smt_rq->idle && smt_rq->nr_running)
|
|
resched_task(smt_rq->idle);
|
|
}
|
|
|
|
for_each_cpu_mask(i, sibling_map)
|
|
spin_unlock(&cpu_rq(i)->lock);
|
|
/*
|
|
* We exit with this_cpu's rq still held and IRQs
|
|
* still disabled:
|
|
*/
|
|
}
|
|
|
|
static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
|
|
{
|
|
struct sched_domain *sd = this_rq->sd;
|
|
cpumask_t sibling_map;
|
|
prio_array_t *array;
|
|
int ret = 0, i;
|
|
task_t *p;
|
|
|
|
if (!(sd->flags & SD_SHARE_CPUPOWER))
|
|
return 0;
|
|
|
|
/*
|
|
* The same locking rules and details apply as for
|
|
* wake_sleeping_dependent():
|
|
*/
|
|
spin_unlock(&this_rq->lock);
|
|
sibling_map = sd->span;
|
|
for_each_cpu_mask(i, sibling_map)
|
|
spin_lock(&cpu_rq(i)->lock);
|
|
cpu_clear(this_cpu, sibling_map);
|
|
|
|
/*
|
|
* Establish next task to be run - it might have gone away because
|
|
* we released the runqueue lock above:
|
|
*/
|
|
if (!this_rq->nr_running)
|
|
goto out_unlock;
|
|
array = this_rq->active;
|
|
if (!array->nr_active)
|
|
array = this_rq->expired;
|
|
BUG_ON(!array->nr_active);
|
|
|
|
p = list_entry(array->queue[sched_find_first_bit(array->bitmap)].next,
|
|
task_t, run_list);
|
|
|
|
for_each_cpu_mask(i, sibling_map) {
|
|
runqueue_t *smt_rq = cpu_rq(i);
|
|
task_t *smt_curr = smt_rq->curr;
|
|
|
|
/*
|
|
* If a user task with lower static priority than the
|
|
* running task on the SMT sibling is trying to schedule,
|
|
* delay it till there is proportionately less timeslice
|
|
* left of the sibling task to prevent a lower priority
|
|
* task from using an unfair proportion of the
|
|
* physical cpu's resources. -ck
|
|
*/
|
|
if (((smt_curr->time_slice * (100 - sd->per_cpu_gain) / 100) >
|
|
task_timeslice(p) || rt_task(smt_curr)) &&
|
|
p->mm && smt_curr->mm && !rt_task(p))
|
|
ret = 1;
|
|
|
|
/*
|
|
* Reschedule a lower priority task on the SMT sibling,
|
|
* or wake it up if it has been put to sleep for priority
|
|
* reasons.
|
|
*/
|
|
if ((((p->time_slice * (100 - sd->per_cpu_gain) / 100) >
|
|
task_timeslice(smt_curr) || rt_task(p)) &&
|
|
smt_curr->mm && p->mm && !rt_task(smt_curr)) ||
|
|
(smt_curr == smt_rq->idle && smt_rq->nr_running))
|
|
resched_task(smt_curr);
|
|
}
|
|
out_unlock:
|
|
for_each_cpu_mask(i, sibling_map)
|
|
spin_unlock(&cpu_rq(i)->lock);
|
|
return ret;
|
|
}
|
|
#else
|
|
static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
|
|
{
|
|
}
|
|
|
|
static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
#if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
|
|
|
|
void fastcall add_preempt_count(int val)
|
|
{
|
|
/*
|
|
* Underflow?
|
|
*/
|
|
BUG_ON(((int)preempt_count() < 0));
|
|
preempt_count() += val;
|
|
/*
|
|
* Spinlock count overflowing soon?
|
|
*/
|
|
BUG_ON((preempt_count() & PREEMPT_MASK) >= PREEMPT_MASK-10);
|
|
}
|
|
EXPORT_SYMBOL(add_preempt_count);
|
|
|
|
void fastcall sub_preempt_count(int val)
|
|
{
|
|
/*
|
|
* Underflow?
|
|
*/
|
|
BUG_ON(val > preempt_count());
|
|
/*
|
|
* Is the spinlock portion underflowing?
|
|
*/
|
|
BUG_ON((val < PREEMPT_MASK) && !(preempt_count() & PREEMPT_MASK));
|
|
preempt_count() -= val;
|
|
}
|
|
EXPORT_SYMBOL(sub_preempt_count);
|
|
|
|
#endif
|
|
|
|
/*
|
|
* schedule() is the main scheduler function.
|
|
*/
|
|
asmlinkage void __sched schedule(void)
|
|
{
|
|
long *switch_count;
|
|
task_t *prev, *next;
|
|
runqueue_t *rq;
|
|
prio_array_t *array;
|
|
struct list_head *queue;
|
|
unsigned long long now;
|
|
unsigned long run_time;
|
|
int cpu, idx;
|
|
|
|
/*
|
|
* Test if we are atomic. Since do_exit() needs to call into
|
|
* schedule() atomically, we ignore that path for now.
|
|
* Otherwise, whine if we are scheduling when we should not be.
|
|
*/
|
|
if (likely(!current->exit_state)) {
|
|
if (unlikely(in_atomic())) {
|
|
printk(KERN_ERR "scheduling while atomic: "
|
|
"%s/0x%08x/%d\n",
|
|
current->comm, preempt_count(), current->pid);
|
|
dump_stack();
|
|
}
|
|
}
|
|
profile_hit(SCHED_PROFILING, __builtin_return_address(0));
|
|
|
|
need_resched:
|
|
preempt_disable();
|
|
prev = current;
|
|
release_kernel_lock(prev);
|
|
need_resched_nonpreemptible:
|
|
rq = this_rq();
|
|
|
|
/*
|
|
* The idle thread is not allowed to schedule!
|
|
* Remove this check after it has been exercised a bit.
|
|
*/
|
|
if (unlikely(prev == rq->idle) && prev->state != TASK_RUNNING) {
|
|
printk(KERN_ERR "bad: scheduling from the idle thread!\n");
|
|
dump_stack();
|
|
}
|
|
|
|
schedstat_inc(rq, sched_cnt);
|
|
now = sched_clock();
|
|
if (likely((long long)(now - prev->timestamp) < NS_MAX_SLEEP_AVG)) {
|
|
run_time = now - prev->timestamp;
|
|
if (unlikely((long long)(now - prev->timestamp) < 0))
|
|
run_time = 0;
|
|
} else
|
|
run_time = NS_MAX_SLEEP_AVG;
|
|
|
|
/*
|
|
* Tasks charged proportionately less run_time at high sleep_avg to
|
|
* delay them losing their interactive status
|
|
*/
|
|
run_time /= (CURRENT_BONUS(prev) ? : 1);
|
|
|
|
spin_lock_irq(&rq->lock);
|
|
|
|
if (unlikely(prev->flags & PF_DEAD))
|
|
prev->state = EXIT_DEAD;
|
|
|
|
switch_count = &prev->nivcsw;
|
|
if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
|
|
switch_count = &prev->nvcsw;
|
|
if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
|
|
unlikely(signal_pending(prev))))
|
|
prev->state = TASK_RUNNING;
|
|
else {
|
|
if (prev->state == TASK_UNINTERRUPTIBLE)
|
|
rq->nr_uninterruptible++;
|
|
deactivate_task(prev, rq);
|
|
}
|
|
}
|
|
|
|
cpu = smp_processor_id();
|
|
if (unlikely(!rq->nr_running)) {
|
|
go_idle:
|
|
idle_balance(cpu, rq);
|
|
if (!rq->nr_running) {
|
|
next = rq->idle;
|
|
rq->expired_timestamp = 0;
|
|
wake_sleeping_dependent(cpu, rq);
|
|
/*
|
|
* wake_sleeping_dependent() might have released
|
|
* the runqueue, so break out if we got new
|
|
* tasks meanwhile:
|
|
*/
|
|
if (!rq->nr_running)
|
|
goto switch_tasks;
|
|
}
|
|
} else {
|
|
if (dependent_sleeper(cpu, rq)) {
|
|
next = rq->idle;
|
|
goto switch_tasks;
|
|
}
|
|
/*
|
|
* dependent_sleeper() releases and reacquires the runqueue
|
|
* lock, hence go into the idle loop if the rq went
|
|
* empty meanwhile:
|
|
*/
|
|
if (unlikely(!rq->nr_running))
|
|
goto go_idle;
|
|
}
|
|
|
|
array = rq->active;
|
|
if (unlikely(!array->nr_active)) {
|
|
/*
|
|
* Switch the active and expired arrays.
|
|
*/
|
|
schedstat_inc(rq, sched_switch);
|
|
rq->active = rq->expired;
|
|
rq->expired = array;
|
|
array = rq->active;
|
|
rq->expired_timestamp = 0;
|
|
rq->best_expired_prio = MAX_PRIO;
|
|
}
|
|
|
|
idx = sched_find_first_bit(array->bitmap);
|
|
queue = array->queue + idx;
|
|
next = list_entry(queue->next, task_t, run_list);
|
|
|
|
if (!rt_task(next) && next->activated > 0) {
|
|
unsigned long long delta = now - next->timestamp;
|
|
if (unlikely((long long)(now - next->timestamp) < 0))
|
|
delta = 0;
|
|
|
|
if (next->activated == 1)
|
|
delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;
|
|
|
|
array = next->array;
|
|
dequeue_task(next, array);
|
|
recalc_task_prio(next, next->timestamp + delta);
|
|
enqueue_task(next, array);
|
|
}
|
|
next->activated = 0;
|
|
switch_tasks:
|
|
if (next == rq->idle)
|
|
schedstat_inc(rq, sched_goidle);
|
|
prefetch(next);
|
|
clear_tsk_need_resched(prev);
|
|
rcu_qsctr_inc(task_cpu(prev));
|
|
|
|
update_cpu_clock(prev, rq, now);
|
|
|
|
prev->sleep_avg -= run_time;
|
|
if ((long)prev->sleep_avg <= 0)
|
|
prev->sleep_avg = 0;
|
|
prev->timestamp = prev->last_ran = now;
|
|
|
|
sched_info_switch(prev, next);
|
|
if (likely(prev != next)) {
|
|
next->timestamp = now;
|
|
rq->nr_switches++;
|
|
rq->curr = next;
|
|
++*switch_count;
|
|
|
|
prepare_arch_switch(rq, next);
|
|
prev = context_switch(rq, prev, next);
|
|
barrier();
|
|
|
|
finish_task_switch(prev);
|
|
} else
|
|
spin_unlock_irq(&rq->lock);
|
|
|
|
prev = current;
|
|
if (unlikely(reacquire_kernel_lock(prev) < 0))
|
|
goto need_resched_nonpreemptible;
|
|
preempt_enable_no_resched();
|
|
if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
|
|
goto need_resched;
|
|
}
|
|
|
|
EXPORT_SYMBOL(schedule);
|
|
|
|
#ifdef CONFIG_PREEMPT
|
|
/*
|
|
* this is is the entry point to schedule() from in-kernel preemption
|
|
* off of preempt_enable. Kernel preemptions off return from interrupt
|
|
* occur there and call schedule directly.
|
|
*/
|
|
asmlinkage void __sched preempt_schedule(void)
|
|
{
|
|
struct thread_info *ti = current_thread_info();
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
struct task_struct *task = current;
|
|
int saved_lock_depth;
|
|
#endif
|
|
/*
|
|
* If there is a non-zero preempt_count or interrupts are disabled,
|
|
* we do not want to preempt the current task. Just return..
|
|
*/
|
|
if (unlikely(ti->preempt_count || irqs_disabled()))
|
|
return;
|
|
|
|
need_resched:
|
|
add_preempt_count(PREEMPT_ACTIVE);
|
|
/*
|
|
* We keep the big kernel semaphore locked, but we
|
|
* clear ->lock_depth so that schedule() doesnt
|
|
* auto-release the semaphore:
|
|
*/
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
saved_lock_depth = task->lock_depth;
|
|
task->lock_depth = -1;
|
|
#endif
|
|
schedule();
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
task->lock_depth = saved_lock_depth;
|
|
#endif
|
|
sub_preempt_count(PREEMPT_ACTIVE);
|
|
|
|
/* we could miss a preemption opportunity between schedule and now */
|
|
barrier();
|
|
if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
|
|
goto need_resched;
|
|
}
|
|
|
|
EXPORT_SYMBOL(preempt_schedule);
|
|
|
|
/*
|
|
* this is is the entry point to schedule() from kernel preemption
|
|
* off of irq context.
|
|
* Note, that this is called and return with irqs disabled. This will
|
|
* protect us against recursive calling from irq.
|
|
*/
|
|
asmlinkage void __sched preempt_schedule_irq(void)
|
|
{
|
|
struct thread_info *ti = current_thread_info();
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
struct task_struct *task = current;
|
|
int saved_lock_depth;
|
|
#endif
|
|
/* Catch callers which need to be fixed*/
|
|
BUG_ON(ti->preempt_count || !irqs_disabled());
|
|
|
|
need_resched:
|
|
add_preempt_count(PREEMPT_ACTIVE);
|
|
/*
|
|
* We keep the big kernel semaphore locked, but we
|
|
* clear ->lock_depth so that schedule() doesnt
|
|
* auto-release the semaphore:
|
|
*/
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
saved_lock_depth = task->lock_depth;
|
|
task->lock_depth = -1;
|
|
#endif
|
|
local_irq_enable();
|
|
schedule();
|
|
local_irq_disable();
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
task->lock_depth = saved_lock_depth;
|
|
#endif
|
|
sub_preempt_count(PREEMPT_ACTIVE);
|
|
|
|
/* we could miss a preemption opportunity between schedule and now */
|
|
barrier();
|
|
if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
|
|
goto need_resched;
|
|
}
|
|
|
|
#endif /* CONFIG_PREEMPT */
|
|
|
|
int default_wake_function(wait_queue_t *curr, unsigned mode, int sync, void *key)
|
|
{
|
|
task_t *p = curr->task;
|
|
return try_to_wake_up(p, mode, sync);
|
|
}
|
|
|
|
EXPORT_SYMBOL(default_wake_function);
|
|
|
|
/*
|
|
* The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
|
|
* wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
|
|
* number) then we wake all the non-exclusive tasks and one exclusive task.
|
|
*
|
|
* There are circumstances in which we can try to wake a task which has already
|
|
* started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
|
|
* zero in this (rare) case, and we handle it by continuing to scan the queue.
|
|
*/
|
|
static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
|
|
int nr_exclusive, int sync, void *key)
|
|
{
|
|
struct list_head *tmp, *next;
|
|
|
|
list_for_each_safe(tmp, next, &q->task_list) {
|
|
wait_queue_t *curr;
|
|
unsigned flags;
|
|
curr = list_entry(tmp, wait_queue_t, task_list);
|
|
flags = curr->flags;
|
|
if (curr->func(curr, mode, sync, key) &&
|
|
(flags & WQ_FLAG_EXCLUSIVE) &&
|
|
!--nr_exclusive)
|
|
break;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* __wake_up - wake up threads blocked on a waitqueue.
|
|
* @q: the waitqueue
|
|
* @mode: which threads
|
|
* @nr_exclusive: how many wake-one or wake-many threads to wake up
|
|
*/
|
|
void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
|
|
int nr_exclusive, void *key)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&q->lock, flags);
|
|
__wake_up_common(q, mode, nr_exclusive, 0, key);
|
|
spin_unlock_irqrestore(&q->lock, flags);
|
|
}
|
|
|
|
EXPORT_SYMBOL(__wake_up);
|
|
|
|
/*
|
|
* Same as __wake_up but called with the spinlock in wait_queue_head_t held.
|
|
*/
|
|
void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
|
|
{
|
|
__wake_up_common(q, mode, 1, 0, NULL);
|
|
}
|
|
|
|
/**
|
|
* __wake_up - sync- wake up threads blocked on a waitqueue.
|
|
* @q: the waitqueue
|
|
* @mode: which threads
|
|
* @nr_exclusive: how many wake-one or wake-many threads to wake up
|
|
*
|
|
* The sync wakeup differs that the waker knows that it will schedule
|
|
* away soon, so while the target thread will be woken up, it will not
|
|
* be migrated to another CPU - ie. the two threads are 'synchronized'
|
|
* with each other. This can prevent needless bouncing between CPUs.
|
|
*
|
|
* On UP it can prevent extra preemption.
|
|
*/
|
|
void fastcall __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
|
|
{
|
|
unsigned long flags;
|
|
int sync = 1;
|
|
|
|
if (unlikely(!q))
|
|
return;
|
|
|
|
if (unlikely(!nr_exclusive))
|
|
sync = 0;
|
|
|
|
spin_lock_irqsave(&q->lock, flags);
|
|
__wake_up_common(q, mode, nr_exclusive, sync, NULL);
|
|
spin_unlock_irqrestore(&q->lock, flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
|
|
|
|
void fastcall complete(struct completion *x)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&x->wait.lock, flags);
|
|
x->done++;
|
|
__wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
|
|
1, 0, NULL);
|
|
spin_unlock_irqrestore(&x->wait.lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(complete);
|
|
|
|
void fastcall complete_all(struct completion *x)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&x->wait.lock, flags);
|
|
x->done += UINT_MAX/2;
|
|
__wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
|
|
0, 0, NULL);
|
|
spin_unlock_irqrestore(&x->wait.lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(complete_all);
|
|
|
|
void fastcall __sched wait_for_completion(struct completion *x)
|
|
{
|
|
might_sleep();
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!x->done) {
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
|
|
wait.flags |= WQ_FLAG_EXCLUSIVE;
|
|
__add_wait_queue_tail(&x->wait, &wait);
|
|
do {
|
|
__set_current_state(TASK_UNINTERRUPTIBLE);
|
|
spin_unlock_irq(&x->wait.lock);
|
|
schedule();
|
|
spin_lock_irq(&x->wait.lock);
|
|
} while (!x->done);
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
}
|
|
x->done--;
|
|
spin_unlock_irq(&x->wait.lock);
|
|
}
|
|
EXPORT_SYMBOL(wait_for_completion);
|
|
|
|
unsigned long fastcall __sched
|
|
wait_for_completion_timeout(struct completion *x, unsigned long timeout)
|
|
{
|
|
might_sleep();
|
|
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!x->done) {
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
|
|
wait.flags |= WQ_FLAG_EXCLUSIVE;
|
|
__add_wait_queue_tail(&x->wait, &wait);
|
|
do {
|
|
__set_current_state(TASK_UNINTERRUPTIBLE);
|
|
spin_unlock_irq(&x->wait.lock);
|
|
timeout = schedule_timeout(timeout);
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!timeout) {
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
goto out;
|
|
}
|
|
} while (!x->done);
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
}
|
|
x->done--;
|
|
out:
|
|
spin_unlock_irq(&x->wait.lock);
|
|
return timeout;
|
|
}
|
|
EXPORT_SYMBOL(wait_for_completion_timeout);
|
|
|
|
int fastcall __sched wait_for_completion_interruptible(struct completion *x)
|
|
{
|
|
int ret = 0;
|
|
|
|
might_sleep();
|
|
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!x->done) {
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
|
|
wait.flags |= WQ_FLAG_EXCLUSIVE;
|
|
__add_wait_queue_tail(&x->wait, &wait);
|
|
do {
|
|
if (signal_pending(current)) {
|
|
ret = -ERESTARTSYS;
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
goto out;
|
|
}
|
|
__set_current_state(TASK_INTERRUPTIBLE);
|
|
spin_unlock_irq(&x->wait.lock);
|
|
schedule();
|
|
spin_lock_irq(&x->wait.lock);
|
|
} while (!x->done);
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
}
|
|
x->done--;
|
|
out:
|
|
spin_unlock_irq(&x->wait.lock);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(wait_for_completion_interruptible);
|
|
|
|
unsigned long fastcall __sched
|
|
wait_for_completion_interruptible_timeout(struct completion *x,
|
|
unsigned long timeout)
|
|
{
|
|
might_sleep();
|
|
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!x->done) {
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
|
|
wait.flags |= WQ_FLAG_EXCLUSIVE;
|
|
__add_wait_queue_tail(&x->wait, &wait);
|
|
do {
|
|
if (signal_pending(current)) {
|
|
timeout = -ERESTARTSYS;
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
goto out;
|
|
}
|
|
__set_current_state(TASK_INTERRUPTIBLE);
|
|
spin_unlock_irq(&x->wait.lock);
|
|
timeout = schedule_timeout(timeout);
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!timeout) {
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
goto out;
|
|
}
|
|
} while (!x->done);
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
}
|
|
x->done--;
|
|
out:
|
|
spin_unlock_irq(&x->wait.lock);
|
|
return timeout;
|
|
}
|
|
EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
|
|
|
|
|
|
#define SLEEP_ON_VAR \
|
|
unsigned long flags; \
|
|
wait_queue_t wait; \
|
|
init_waitqueue_entry(&wait, current);
|
|
|
|
#define SLEEP_ON_HEAD \
|
|
spin_lock_irqsave(&q->lock,flags); \
|
|
__add_wait_queue(q, &wait); \
|
|
spin_unlock(&q->lock);
|
|
|
|
#define SLEEP_ON_TAIL \
|
|
spin_lock_irq(&q->lock); \
|
|
__remove_wait_queue(q, &wait); \
|
|
spin_unlock_irqrestore(&q->lock, flags);
|
|
|
|
void fastcall __sched interruptible_sleep_on(wait_queue_head_t *q)
|
|
{
|
|
SLEEP_ON_VAR
|
|
|
|
current->state = TASK_INTERRUPTIBLE;
|
|
|
|
SLEEP_ON_HEAD
|
|
schedule();
|
|
SLEEP_ON_TAIL
|
|
}
|
|
|
|
EXPORT_SYMBOL(interruptible_sleep_on);
|
|
|
|
long fastcall __sched interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
|
|
{
|
|
SLEEP_ON_VAR
|
|
|
|
current->state = TASK_INTERRUPTIBLE;
|
|
|
|
SLEEP_ON_HEAD
|
|
timeout = schedule_timeout(timeout);
|
|
SLEEP_ON_TAIL
|
|
|
|
return timeout;
|
|
}
|
|
|
|
EXPORT_SYMBOL(interruptible_sleep_on_timeout);
|
|
|
|
void fastcall __sched sleep_on(wait_queue_head_t *q)
|
|
{
|
|
SLEEP_ON_VAR
|
|
|
|
current->state = TASK_UNINTERRUPTIBLE;
|
|
|
|
SLEEP_ON_HEAD
|
|
schedule();
|
|
SLEEP_ON_TAIL
|
|
}
|
|
|
|
EXPORT_SYMBOL(sleep_on);
|
|
|
|
long fastcall __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
|
|
{
|
|
SLEEP_ON_VAR
|
|
|
|
current->state = TASK_UNINTERRUPTIBLE;
|
|
|
|
SLEEP_ON_HEAD
|
|
timeout = schedule_timeout(timeout);
|
|
SLEEP_ON_TAIL
|
|
|
|
return timeout;
|
|
}
|
|
|
|
EXPORT_SYMBOL(sleep_on_timeout);
|
|
|
|
void set_user_nice(task_t *p, long nice)
|
|
{
|
|
unsigned long flags;
|
|
prio_array_t *array;
|
|
runqueue_t *rq;
|
|
int old_prio, new_prio, delta;
|
|
|
|
if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
|
|
return;
|
|
/*
|
|
* We have to be careful, if called from sys_setpriority(),
|
|
* the task might be in the middle of scheduling on another CPU.
|
|
*/
|
|
rq = task_rq_lock(p, &flags);
|
|
/*
|
|
* The RT priorities are set via sched_setscheduler(), but we still
|
|
* allow the 'normal' nice value to be set - but as expected
|
|
* it wont have any effect on scheduling until the task is
|
|
* not SCHED_NORMAL:
|
|
*/
|
|
if (rt_task(p)) {
|
|
p->static_prio = NICE_TO_PRIO(nice);
|
|
goto out_unlock;
|
|
}
|
|
array = p->array;
|
|
if (array)
|
|
dequeue_task(p, array);
|
|
|
|
old_prio = p->prio;
|
|
new_prio = NICE_TO_PRIO(nice);
|
|
delta = new_prio - old_prio;
|
|
p->static_prio = NICE_TO_PRIO(nice);
|
|
p->prio += delta;
|
|
|
|
if (array) {
|
|
enqueue_task(p, array);
|
|
/*
|
|
* If the task increased its priority or is running and
|
|
* lowered its priority, then reschedule its CPU:
|
|
*/
|
|
if (delta < 0 || (delta > 0 && task_running(rq, p)))
|
|
resched_task(rq->curr);
|
|
}
|
|
out_unlock:
|
|
task_rq_unlock(rq, &flags);
|
|
}
|
|
|
|
EXPORT_SYMBOL(set_user_nice);
|
|
|
|
#ifdef __ARCH_WANT_SYS_NICE
|
|
|
|
/*
|
|
* sys_nice - change the priority of the current process.
|
|
* @increment: priority increment
|
|
*
|
|
* sys_setpriority is a more generic, but much slower function that
|
|
* does similar things.
|
|
*/
|
|
asmlinkage long sys_nice(int increment)
|
|
{
|
|
int retval;
|
|
long nice;
|
|
|
|
/*
|
|
* Setpriority might change our priority at the same moment.
|
|
* We don't have to worry. Conceptually one call occurs first
|
|
* and we have a single winner.
|
|
*/
|
|
if (increment < 0) {
|
|
if (!capable(CAP_SYS_NICE))
|
|
return -EPERM;
|
|
if (increment < -40)
|
|
increment = -40;
|
|
}
|
|
if (increment > 40)
|
|
increment = 40;
|
|
|
|
nice = PRIO_TO_NICE(current->static_prio) + increment;
|
|
if (nice < -20)
|
|
nice = -20;
|
|
if (nice > 19)
|
|
nice = 19;
|
|
|
|
retval = security_task_setnice(current, nice);
|
|
if (retval)
|
|
return retval;
|
|
|
|
set_user_nice(current, nice);
|
|
return 0;
|
|
}
|
|
|
|
#endif
|
|
|
|
/**
|
|
* task_prio - return the priority value of a given task.
|
|
* @p: the task in question.
|
|
*
|
|
* This is the priority value as seen by users in /proc.
|
|
* RT tasks are offset by -200. Normal tasks are centered
|
|
* around 0, value goes from -16 to +15.
|
|
*/
|
|
int task_prio(const task_t *p)
|
|
{
|
|
return p->prio - MAX_RT_PRIO;
|
|
}
|
|
|
|
/**
|
|
* task_nice - return the nice value of a given task.
|
|
* @p: the task in question.
|
|
*/
|
|
int task_nice(const task_t *p)
|
|
{
|
|
return TASK_NICE(p);
|
|
}
|
|
|
|
/*
|
|
* The only users of task_nice are binfmt_elf and binfmt_elf32.
|
|
* binfmt_elf is no longer modular, but binfmt_elf32 still is.
|
|
* Therefore, task_nice is needed if there is a compat_mode.
|
|
*/
|
|
#ifdef CONFIG_COMPAT
|
|
EXPORT_SYMBOL_GPL(task_nice);
|
|
#endif
|
|
|
|
/**
|
|
* idle_cpu - is a given cpu idle currently?
|
|
* @cpu: the processor in question.
|
|
*/
|
|
int idle_cpu(int cpu)
|
|
{
|
|
return cpu_curr(cpu) == cpu_rq(cpu)->idle;
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(idle_cpu);
|
|
|
|
/**
|
|
* idle_task - return the idle task for a given cpu.
|
|
* @cpu: the processor in question.
|
|
*/
|
|
task_t *idle_task(int cpu)
|
|
{
|
|
return cpu_rq(cpu)->idle;
|
|
}
|
|
|
|
/**
|
|
* find_process_by_pid - find a process with a matching PID value.
|
|
* @pid: the pid in question.
|
|
*/
|
|
static inline task_t *find_process_by_pid(pid_t pid)
|
|
{
|
|
return pid ? find_task_by_pid(pid) : current;
|
|
}
|
|
|
|
/* Actually do priority change: must hold rq lock. */
|
|
static void __setscheduler(struct task_struct *p, int policy, int prio)
|
|
{
|
|
BUG_ON(p->array);
|
|
p->policy = policy;
|
|
p->rt_priority = prio;
|
|
if (policy != SCHED_NORMAL)
|
|
p->prio = MAX_USER_RT_PRIO-1 - p->rt_priority;
|
|
else
|
|
p->prio = p->static_prio;
|
|
}
|
|
|
|
/**
|
|
* sched_setscheduler - change the scheduling policy and/or RT priority of
|
|
* a thread.
|
|
* @p: the task in question.
|
|
* @policy: new policy.
|
|
* @param: structure containing the new RT priority.
|
|
*/
|
|
int sched_setscheduler(struct task_struct *p, int policy, struct sched_param *param)
|
|
{
|
|
int retval;
|
|
int oldprio, oldpolicy = -1;
|
|
prio_array_t *array;
|
|
unsigned long flags;
|
|
runqueue_t *rq;
|
|
|
|
recheck:
|
|
/* double check policy once rq lock held */
|
|
if (policy < 0)
|
|
policy = oldpolicy = p->policy;
|
|
else if (policy != SCHED_FIFO && policy != SCHED_RR &&
|
|
policy != SCHED_NORMAL)
|
|
return -EINVAL;
|
|
/*
|
|
* Valid priorities for SCHED_FIFO and SCHED_RR are
|
|
* 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0.
|
|
*/
|
|
if (param->sched_priority < 0 ||
|
|
param->sched_priority > MAX_USER_RT_PRIO-1)
|
|
return -EINVAL;
|
|
if ((policy == SCHED_NORMAL) != (param->sched_priority == 0))
|
|
return -EINVAL;
|
|
|
|
if ((policy == SCHED_FIFO || policy == SCHED_RR) &&
|
|
!capable(CAP_SYS_NICE))
|
|
return -EPERM;
|
|
if ((current->euid != p->euid) && (current->euid != p->uid) &&
|
|
!capable(CAP_SYS_NICE))
|
|
return -EPERM;
|
|
|
|
retval = security_task_setscheduler(p, policy, param);
|
|
if (retval)
|
|
return retval;
|
|
/*
|
|
* To be able to change p->policy safely, the apropriate
|
|
* runqueue lock must be held.
|
|
*/
|
|
rq = task_rq_lock(p, &flags);
|
|
/* recheck policy now with rq lock held */
|
|
if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
|
|
policy = oldpolicy = -1;
|
|
task_rq_unlock(rq, &flags);
|
|
goto recheck;
|
|
}
|
|
array = p->array;
|
|
if (array)
|
|
deactivate_task(p, rq);
|
|
oldprio = p->prio;
|
|
__setscheduler(p, policy, param->sched_priority);
|
|
if (array) {
|
|
__activate_task(p, rq);
|
|
/*
|
|
* Reschedule if we are currently running on this runqueue and
|
|
* our priority decreased, or if we are not currently running on
|
|
* this runqueue and our priority is higher than the current's
|
|
*/
|
|
if (task_running(rq, p)) {
|
|
if (p->prio > oldprio)
|
|
resched_task(rq->curr);
|
|
} else if (TASK_PREEMPTS_CURR(p, rq))
|
|
resched_task(rq->curr);
|
|
}
|
|
task_rq_unlock(rq, &flags);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(sched_setscheduler);
|
|
|
|
static int do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
|
|
{
|
|
int retval;
|
|
struct sched_param lparam;
|
|
struct task_struct *p;
|
|
|
|
if (!param || pid < 0)
|
|
return -EINVAL;
|
|
if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
|
|
return -EFAULT;
|
|
read_lock_irq(&tasklist_lock);
|
|
p = find_process_by_pid(pid);
|
|
if (!p) {
|
|
read_unlock_irq(&tasklist_lock);
|
|
return -ESRCH;
|
|
}
|
|
retval = sched_setscheduler(p, policy, &lparam);
|
|
read_unlock_irq(&tasklist_lock);
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_setscheduler - set/change the scheduler policy and RT priority
|
|
* @pid: the pid in question.
|
|
* @policy: new policy.
|
|
* @param: structure containing the new RT priority.
|
|
*/
|
|
asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
|
|
struct sched_param __user *param)
|
|
{
|
|
return do_sched_setscheduler(pid, policy, param);
|
|
}
|
|
|
|
/**
|
|
* sys_sched_setparam - set/change the RT priority of a thread
|
|
* @pid: the pid in question.
|
|
* @param: structure containing the new RT priority.
|
|
*/
|
|
asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param)
|
|
{
|
|
return do_sched_setscheduler(pid, -1, param);
|
|
}
|
|
|
|
/**
|
|
* sys_sched_getscheduler - get the policy (scheduling class) of a thread
|
|
* @pid: the pid in question.
|
|
*/
|
|
asmlinkage long sys_sched_getscheduler(pid_t pid)
|
|
{
|
|
int retval = -EINVAL;
|
|
task_t *p;
|
|
|
|
if (pid < 0)
|
|
goto out_nounlock;
|
|
|
|
retval = -ESRCH;
|
|
read_lock(&tasklist_lock);
|
|
p = find_process_by_pid(pid);
|
|
if (p) {
|
|
retval = security_task_getscheduler(p);
|
|
if (!retval)
|
|
retval = p->policy;
|
|
}
|
|
read_unlock(&tasklist_lock);
|
|
|
|
out_nounlock:
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_getscheduler - get the RT priority of a thread
|
|
* @pid: the pid in question.
|
|
* @param: structure containing the RT priority.
|
|
*/
|
|
asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param)
|
|
{
|
|
struct sched_param lp;
|
|
int retval = -EINVAL;
|
|
task_t *p;
|
|
|
|
if (!param || pid < 0)
|
|
goto out_nounlock;
|
|
|
|
read_lock(&tasklist_lock);
|
|
p = find_process_by_pid(pid);
|
|
retval = -ESRCH;
|
|
if (!p)
|
|
goto out_unlock;
|
|
|
|
retval = security_task_getscheduler(p);
|
|
if (retval)
|
|
goto out_unlock;
|
|
|
|
lp.sched_priority = p->rt_priority;
|
|
read_unlock(&tasklist_lock);
|
|
|
|
/*
|
|
* This one might sleep, we cannot do it with a spinlock held ...
|
|
*/
|
|
retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
|
|
|
|
out_nounlock:
|
|
return retval;
|
|
|
|
out_unlock:
|
|
read_unlock(&tasklist_lock);
|
|
return retval;
|
|
}
|
|
|
|
long sched_setaffinity(pid_t pid, cpumask_t new_mask)
|
|
{
|
|
task_t *p;
|
|
int retval;
|
|
cpumask_t cpus_allowed;
|
|
|
|
lock_cpu_hotplug();
|
|
read_lock(&tasklist_lock);
|
|
|
|
p = find_process_by_pid(pid);
|
|
if (!p) {
|
|
read_unlock(&tasklist_lock);
|
|
unlock_cpu_hotplug();
|
|
return -ESRCH;
|
|
}
|
|
|
|
/*
|
|
* It is not safe to call set_cpus_allowed with the
|
|
* tasklist_lock held. We will bump the task_struct's
|
|
* usage count and then drop tasklist_lock.
|
|
*/
|
|
get_task_struct(p);
|
|
read_unlock(&tasklist_lock);
|
|
|
|
retval = -EPERM;
|
|
if ((current->euid != p->euid) && (current->euid != p->uid) &&
|
|
!capable(CAP_SYS_NICE))
|
|
goto out_unlock;
|
|
|
|
cpus_allowed = cpuset_cpus_allowed(p);
|
|
cpus_and(new_mask, new_mask, cpus_allowed);
|
|
retval = set_cpus_allowed(p, new_mask);
|
|
|
|
out_unlock:
|
|
put_task_struct(p);
|
|
unlock_cpu_hotplug();
|
|
return retval;
|
|
}
|
|
|
|
static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
|
|
cpumask_t *new_mask)
|
|
{
|
|
if (len < sizeof(cpumask_t)) {
|
|
memset(new_mask, 0, sizeof(cpumask_t));
|
|
} else if (len > sizeof(cpumask_t)) {
|
|
len = sizeof(cpumask_t);
|
|
}
|
|
return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_setaffinity - set the cpu affinity of a process
|
|
* @pid: pid of the process
|
|
* @len: length in bytes of the bitmask pointed to by user_mask_ptr
|
|
* @user_mask_ptr: user-space pointer to the new cpu mask
|
|
*/
|
|
asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
|
|
unsigned long __user *user_mask_ptr)
|
|
{
|
|
cpumask_t new_mask;
|
|
int retval;
|
|
|
|
retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
|
|
if (retval)
|
|
return retval;
|
|
|
|
return sched_setaffinity(pid, new_mask);
|
|
}
|
|
|
|
/*
|
|
* Represents all cpu's present in the system
|
|
* In systems capable of hotplug, this map could dynamically grow
|
|
* as new cpu's are detected in the system via any platform specific
|
|
* method, such as ACPI for e.g.
|
|
*/
|
|
|
|
cpumask_t cpu_present_map;
|
|
EXPORT_SYMBOL(cpu_present_map);
|
|
|
|
#ifndef CONFIG_SMP
|
|
cpumask_t cpu_online_map = CPU_MASK_ALL;
|
|
cpumask_t cpu_possible_map = CPU_MASK_ALL;
|
|
#endif
|
|
|
|
long sched_getaffinity(pid_t pid, cpumask_t *mask)
|
|
{
|
|
int retval;
|
|
task_t *p;
|
|
|
|
lock_cpu_hotplug();
|
|
read_lock(&tasklist_lock);
|
|
|
|
retval = -ESRCH;
|
|
p = find_process_by_pid(pid);
|
|
if (!p)
|
|
goto out_unlock;
|
|
|
|
retval = 0;
|
|
cpus_and(*mask, p->cpus_allowed, cpu_possible_map);
|
|
|
|
out_unlock:
|
|
read_unlock(&tasklist_lock);
|
|
unlock_cpu_hotplug();
|
|
if (retval)
|
|
return retval;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_getaffinity - get the cpu affinity of a process
|
|
* @pid: pid of the process
|
|
* @len: length in bytes of the bitmask pointed to by user_mask_ptr
|
|
* @user_mask_ptr: user-space pointer to hold the current cpu mask
|
|
*/
|
|
asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
|
|
unsigned long __user *user_mask_ptr)
|
|
{
|
|
int ret;
|
|
cpumask_t mask;
|
|
|
|
if (len < sizeof(cpumask_t))
|
|
return -EINVAL;
|
|
|
|
ret = sched_getaffinity(pid, &mask);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
|
|
return -EFAULT;
|
|
|
|
return sizeof(cpumask_t);
|
|
}
|
|
|
|
/**
|
|
* sys_sched_yield - yield the current processor to other threads.
|
|
*
|
|
* this function yields the current CPU by moving the calling thread
|
|
* to the expired array. If there are no other threads running on this
|
|
* CPU then this function will return.
|
|
*/
|
|
asmlinkage long sys_sched_yield(void)
|
|
{
|
|
runqueue_t *rq = this_rq_lock();
|
|
prio_array_t *array = current->array;
|
|
prio_array_t *target = rq->expired;
|
|
|
|
schedstat_inc(rq, yld_cnt);
|
|
/*
|
|
* We implement yielding by moving the task into the expired
|
|
* queue.
|
|
*
|
|
* (special rule: RT tasks will just roundrobin in the active
|
|
* array.)
|
|
*/
|
|
if (rt_task(current))
|
|
target = rq->active;
|
|
|
|
if (current->array->nr_active == 1) {
|
|
schedstat_inc(rq, yld_act_empty);
|
|
if (!rq->expired->nr_active)
|
|
schedstat_inc(rq, yld_both_empty);
|
|
} else if (!rq->expired->nr_active)
|
|
schedstat_inc(rq, yld_exp_empty);
|
|
|
|
if (array != target) {
|
|
dequeue_task(current, array);
|
|
enqueue_task(current, target);
|
|
} else
|
|
/*
|
|
* requeue_task is cheaper so perform that if possible.
|
|
*/
|
|
requeue_task(current, array);
|
|
|
|
/*
|
|
* Since we are going to call schedule() anyway, there's
|
|
* no need to preempt or enable interrupts:
|
|
*/
|
|
__release(rq->lock);
|
|
_raw_spin_unlock(&rq->lock);
|
|
preempt_enable_no_resched();
|
|
|
|
schedule();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static inline void __cond_resched(void)
|
|
{
|
|
do {
|
|
add_preempt_count(PREEMPT_ACTIVE);
|
|
schedule();
|
|
sub_preempt_count(PREEMPT_ACTIVE);
|
|
} while (need_resched());
|
|
}
|
|
|
|
int __sched cond_resched(void)
|
|
{
|
|
if (need_resched()) {
|
|
__cond_resched();
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(cond_resched);
|
|
|
|
/*
|
|
* cond_resched_lock() - if a reschedule is pending, drop the given lock,
|
|
* call schedule, and on return reacquire the lock.
|
|
*
|
|
* This works OK both with and without CONFIG_PREEMPT. We do strange low-level
|
|
* operations here to prevent schedule() from being called twice (once via
|
|
* spin_unlock(), once by hand).
|
|
*/
|
|
int cond_resched_lock(spinlock_t * lock)
|
|
{
|
|
if (need_lockbreak(lock)) {
|
|
spin_unlock(lock);
|
|
cpu_relax();
|
|
spin_lock(lock);
|
|
}
|
|
if (need_resched()) {
|
|
_raw_spin_unlock(lock);
|
|
preempt_enable_no_resched();
|
|
__cond_resched();
|
|
spin_lock(lock);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(cond_resched_lock);
|
|
|
|
int __sched cond_resched_softirq(void)
|
|
{
|
|
BUG_ON(!in_softirq());
|
|
|
|
if (need_resched()) {
|
|
__local_bh_enable();
|
|
__cond_resched();
|
|
local_bh_disable();
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(cond_resched_softirq);
|
|
|
|
|
|
/**
|
|
* yield - yield the current processor to other threads.
|
|
*
|
|
* this is a shortcut for kernel-space yielding - it marks the
|
|
* thread runnable and calls sys_sched_yield().
|
|
*/
|
|
void __sched yield(void)
|
|
{
|
|
set_current_state(TASK_RUNNING);
|
|
sys_sched_yield();
|
|
}
|
|
|
|
EXPORT_SYMBOL(yield);
|
|
|
|
/*
|
|
* This task is about to go to sleep on IO. Increment rq->nr_iowait so
|
|
* that process accounting knows that this is a task in IO wait state.
|
|
*
|
|
* But don't do that if it is a deliberate, throttling IO wait (this task
|
|
* has set its backing_dev_info: the queue against which it should throttle)
|
|
*/
|
|
void __sched io_schedule(void)
|
|
{
|
|
struct runqueue *rq = &per_cpu(runqueues, _smp_processor_id());
|
|
|
|
atomic_inc(&rq->nr_iowait);
|
|
schedule();
|
|
atomic_dec(&rq->nr_iowait);
|
|
}
|
|
|
|
EXPORT_SYMBOL(io_schedule);
|
|
|
|
long __sched io_schedule_timeout(long timeout)
|
|
{
|
|
struct runqueue *rq = &per_cpu(runqueues, _smp_processor_id());
|
|
long ret;
|
|
|
|
atomic_inc(&rq->nr_iowait);
|
|
ret = schedule_timeout(timeout);
|
|
atomic_dec(&rq->nr_iowait);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_get_priority_max - return maximum RT priority.
|
|
* @policy: scheduling class.
|
|
*
|
|
* this syscall returns the maximum rt_priority that can be used
|
|
* by a given scheduling class.
|
|
*/
|
|
asmlinkage long sys_sched_get_priority_max(int policy)
|
|
{
|
|
int ret = -EINVAL;
|
|
|
|
switch (policy) {
|
|
case SCHED_FIFO:
|
|
case SCHED_RR:
|
|
ret = MAX_USER_RT_PRIO-1;
|
|
break;
|
|
case SCHED_NORMAL:
|
|
ret = 0;
|
|
break;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_get_priority_min - return minimum RT priority.
|
|
* @policy: scheduling class.
|
|
*
|
|
* this syscall returns the minimum rt_priority that can be used
|
|
* by a given scheduling class.
|
|
*/
|
|
asmlinkage long sys_sched_get_priority_min(int policy)
|
|
{
|
|
int ret = -EINVAL;
|
|
|
|
switch (policy) {
|
|
case SCHED_FIFO:
|
|
case SCHED_RR:
|
|
ret = 1;
|
|
break;
|
|
case SCHED_NORMAL:
|
|
ret = 0;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_rr_get_interval - return the default timeslice of a process.
|
|
* @pid: pid of the process.
|
|
* @interval: userspace pointer to the timeslice value.
|
|
*
|
|
* this syscall writes the default timeslice value of a given process
|
|
* into the user-space timespec buffer. A value of '0' means infinity.
|
|
*/
|
|
asmlinkage
|
|
long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
|
|
{
|
|
int retval = -EINVAL;
|
|
struct timespec t;
|
|
task_t *p;
|
|
|
|
if (pid < 0)
|
|
goto out_nounlock;
|
|
|
|
retval = -ESRCH;
|
|
read_lock(&tasklist_lock);
|
|
p = find_process_by_pid(pid);
|
|
if (!p)
|
|
goto out_unlock;
|
|
|
|
retval = security_task_getscheduler(p);
|
|
if (retval)
|
|
goto out_unlock;
|
|
|
|
jiffies_to_timespec(p->policy & SCHED_FIFO ?
|
|
0 : task_timeslice(p), &t);
|
|
read_unlock(&tasklist_lock);
|
|
retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
|
|
out_nounlock:
|
|
return retval;
|
|
out_unlock:
|
|
read_unlock(&tasklist_lock);
|
|
return retval;
|
|
}
|
|
|
|
static inline struct task_struct *eldest_child(struct task_struct *p)
|
|
{
|
|
if (list_empty(&p->children)) return NULL;
|
|
return list_entry(p->children.next,struct task_struct,sibling);
|
|
}
|
|
|
|
static inline struct task_struct *older_sibling(struct task_struct *p)
|
|
{
|
|
if (p->sibling.prev==&p->parent->children) return NULL;
|
|
return list_entry(p->sibling.prev,struct task_struct,sibling);
|
|
}
|
|
|
|
static inline struct task_struct *younger_sibling(struct task_struct *p)
|
|
{
|
|
if (p->sibling.next==&p->parent->children) return NULL;
|
|
return list_entry(p->sibling.next,struct task_struct,sibling);
|
|
}
|
|
|
|
static void show_task(task_t * p)
|
|
{
|
|
task_t *relative;
|
|
unsigned state;
|
|
unsigned long free = 0;
|
|
static const char *stat_nam[] = { "R", "S", "D", "T", "t", "Z", "X" };
|
|
|
|
printk("%-13.13s ", p->comm);
|
|
state = p->state ? __ffs(p->state) + 1 : 0;
|
|
if (state < ARRAY_SIZE(stat_nam))
|
|
printk(stat_nam[state]);
|
|
else
|
|
printk("?");
|
|
#if (BITS_PER_LONG == 32)
|
|
if (state == TASK_RUNNING)
|
|
printk(" running ");
|
|
else
|
|
printk(" %08lX ", thread_saved_pc(p));
|
|
#else
|
|
if (state == TASK_RUNNING)
|
|
printk(" running task ");
|
|
else
|
|
printk(" %016lx ", thread_saved_pc(p));
|
|
#endif
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE
|
|
{
|
|
unsigned long * n = (unsigned long *) (p->thread_info+1);
|
|
while (!*n)
|
|
n++;
|
|
free = (unsigned long) n - (unsigned long)(p->thread_info+1);
|
|
}
|
|
#endif
|
|
printk("%5lu %5d %6d ", free, p->pid, p->parent->pid);
|
|
if ((relative = eldest_child(p)))
|
|
printk("%5d ", relative->pid);
|
|
else
|
|
printk(" ");
|
|
if ((relative = younger_sibling(p)))
|
|
printk("%7d", relative->pid);
|
|
else
|
|
printk(" ");
|
|
if ((relative = older_sibling(p)))
|
|
printk(" %5d", relative->pid);
|
|
else
|
|
printk(" ");
|
|
if (!p->mm)
|
|
printk(" (L-TLB)\n");
|
|
else
|
|
printk(" (NOTLB)\n");
|
|
|
|
if (state != TASK_RUNNING)
|
|
show_stack(p, NULL);
|
|
}
|
|
|
|
void show_state(void)
|
|
{
|
|
task_t *g, *p;
|
|
|
|
#if (BITS_PER_LONG == 32)
|
|
printk("\n"
|
|
" sibling\n");
|
|
printk(" task PC pid father child younger older\n");
|
|
#else
|
|
printk("\n"
|
|
" sibling\n");
|
|
printk(" task PC pid father child younger older\n");
|
|
#endif
|
|
read_lock(&tasklist_lock);
|
|
do_each_thread(g, p) {
|
|
/*
|
|
* reset the NMI-timeout, listing all files on a slow
|
|
* console might take alot of time:
|
|
*/
|
|
touch_nmi_watchdog();
|
|
show_task(p);
|
|
} while_each_thread(g, p);
|
|
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
|
|
void __devinit init_idle(task_t *idle, int cpu)
|
|
{
|
|
runqueue_t *rq = cpu_rq(cpu);
|
|
unsigned long flags;
|
|
|
|
idle->sleep_avg = 0;
|
|
idle->array = NULL;
|
|
idle->prio = MAX_PRIO;
|
|
idle->state = TASK_RUNNING;
|
|
idle->cpus_allowed = cpumask_of_cpu(cpu);
|
|
set_task_cpu(idle, cpu);
|
|
|
|
spin_lock_irqsave(&rq->lock, flags);
|
|
rq->curr = rq->idle = idle;
|
|
set_tsk_need_resched(idle);
|
|
spin_unlock_irqrestore(&rq->lock, flags);
|
|
|
|
/* Set the preempt count _outside_ the spinlocks! */
|
|
#if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
|
|
idle->thread_info->preempt_count = (idle->lock_depth >= 0);
|
|
#else
|
|
idle->thread_info->preempt_count = 0;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* In a system that switches off the HZ timer nohz_cpu_mask
|
|
* indicates which cpus entered this state. This is used
|
|
* in the rcu update to wait only for active cpus. For system
|
|
* which do not switch off the HZ timer nohz_cpu_mask should
|
|
* always be CPU_MASK_NONE.
|
|
*/
|
|
cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* This is how migration works:
|
|
*
|
|
* 1) we queue a migration_req_t structure in the source CPU's
|
|
* runqueue and wake up that CPU's migration thread.
|
|
* 2) we down() the locked semaphore => thread blocks.
|
|
* 3) migration thread wakes up (implicitly it forces the migrated
|
|
* thread off the CPU)
|
|
* 4) it gets the migration request and checks whether the migrated
|
|
* task is still in the wrong runqueue.
|
|
* 5) if it's in the wrong runqueue then the migration thread removes
|
|
* it and puts it into the right queue.
|
|
* 6) migration thread up()s the semaphore.
|
|
* 7) we wake up and the migration is done.
|
|
*/
|
|
|
|
/*
|
|
* Change a given task's CPU affinity. Migrate the thread to a
|
|
* proper CPU and schedule it away if the CPU it's executing on
|
|
* is removed from the allowed bitmask.
|
|
*
|
|
* NOTE: the caller must have a valid reference to the task, the
|
|
* task must not exit() & deallocate itself prematurely. The
|
|
* call is not atomic; no spinlocks may be held.
|
|
*/
|
|
int set_cpus_allowed(task_t *p, cpumask_t new_mask)
|
|
{
|
|
unsigned long flags;
|
|
int ret = 0;
|
|
migration_req_t req;
|
|
runqueue_t *rq;
|
|
|
|
rq = task_rq_lock(p, &flags);
|
|
if (!cpus_intersects(new_mask, cpu_online_map)) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
p->cpus_allowed = new_mask;
|
|
/* Can the task run on the task's current CPU? If so, we're done */
|
|
if (cpu_isset(task_cpu(p), new_mask))
|
|
goto out;
|
|
|
|
if (migrate_task(p, any_online_cpu(new_mask), &req)) {
|
|
/* Need help from migration thread: drop lock and wait. */
|
|
task_rq_unlock(rq, &flags);
|
|
wake_up_process(rq->migration_thread);
|
|
wait_for_completion(&req.done);
|
|
tlb_migrate_finish(p->mm);
|
|
return 0;
|
|
}
|
|
out:
|
|
task_rq_unlock(rq, &flags);
|
|
return ret;
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(set_cpus_allowed);
|
|
|
|
/*
|
|
* Move (not current) task off this cpu, onto dest cpu. We're doing
|
|
* this because either it can't run here any more (set_cpus_allowed()
|
|
* away from this CPU, or CPU going down), or because we're
|
|
* attempting to rebalance this task on exec (sched_exec).
|
|
*
|
|
* So we race with normal scheduler movements, but that's OK, as long
|
|
* as the task is no longer on this CPU.
|
|
*/
|
|
static void __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
|
|
{
|
|
runqueue_t *rq_dest, *rq_src;
|
|
|
|
if (unlikely(cpu_is_offline(dest_cpu)))
|
|
return;
|
|
|
|
rq_src = cpu_rq(src_cpu);
|
|
rq_dest = cpu_rq(dest_cpu);
|
|
|
|
double_rq_lock(rq_src, rq_dest);
|
|
/* Already moved. */
|
|
if (task_cpu(p) != src_cpu)
|
|
goto out;
|
|
/* Affinity changed (again). */
|
|
if (!cpu_isset(dest_cpu, p->cpus_allowed))
|
|
goto out;
|
|
|
|
set_task_cpu(p, dest_cpu);
|
|
if (p->array) {
|
|
/*
|
|
* Sync timestamp with rq_dest's before activating.
|
|
* The same thing could be achieved by doing this step
|
|
* afterwards, and pretending it was a local activate.
|
|
* This way is cleaner and logically correct.
|
|
*/
|
|
p->timestamp = p->timestamp - rq_src->timestamp_last_tick
|
|
+ rq_dest->timestamp_last_tick;
|
|
deactivate_task(p, rq_src);
|
|
activate_task(p, rq_dest, 0);
|
|
if (TASK_PREEMPTS_CURR(p, rq_dest))
|
|
resched_task(rq_dest->curr);
|
|
}
|
|
|
|
out:
|
|
double_rq_unlock(rq_src, rq_dest);
|
|
}
|
|
|
|
/*
|
|
* migration_thread - this is a highprio system thread that performs
|
|
* thread migration by bumping thread off CPU then 'pushing' onto
|
|
* another runqueue.
|
|
*/
|
|
static int migration_thread(void * data)
|
|
{
|
|
runqueue_t *rq;
|
|
int cpu = (long)data;
|
|
|
|
rq = cpu_rq(cpu);
|
|
BUG_ON(rq->migration_thread != current);
|
|
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
while (!kthread_should_stop()) {
|
|
struct list_head *head;
|
|
migration_req_t *req;
|
|
|
|
if (current->flags & PF_FREEZE)
|
|
refrigerator(PF_FREEZE);
|
|
|
|
spin_lock_irq(&rq->lock);
|
|
|
|
if (cpu_is_offline(cpu)) {
|
|
spin_unlock_irq(&rq->lock);
|
|
goto wait_to_die;
|
|
}
|
|
|
|
if (rq->active_balance) {
|
|
active_load_balance(rq, cpu);
|
|
rq->active_balance = 0;
|
|
}
|
|
|
|
head = &rq->migration_queue;
|
|
|
|
if (list_empty(head)) {
|
|
spin_unlock_irq(&rq->lock);
|
|
schedule();
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
continue;
|
|
}
|
|
req = list_entry(head->next, migration_req_t, list);
|
|
list_del_init(head->next);
|
|
|
|
if (req->type == REQ_MOVE_TASK) {
|
|
spin_unlock(&rq->lock);
|
|
__migrate_task(req->task, cpu, req->dest_cpu);
|
|
local_irq_enable();
|
|
} else if (req->type == REQ_SET_DOMAIN) {
|
|
rq->sd = req->sd;
|
|
spin_unlock_irq(&rq->lock);
|
|
} else {
|
|
spin_unlock_irq(&rq->lock);
|
|
WARN_ON(1);
|
|
}
|
|
|
|
complete(&req->done);
|
|
}
|
|
__set_current_state(TASK_RUNNING);
|
|
return 0;
|
|
|
|
wait_to_die:
|
|
/* Wait for kthread_stop */
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
while (!kthread_should_stop()) {
|
|
schedule();
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
}
|
|
__set_current_state(TASK_RUNNING);
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
/* Figure out where task on dead CPU should go, use force if neccessary. */
|
|
static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *tsk)
|
|
{
|
|
int dest_cpu;
|
|
cpumask_t mask;
|
|
|
|
/* On same node? */
|
|
mask = node_to_cpumask(cpu_to_node(dead_cpu));
|
|
cpus_and(mask, mask, tsk->cpus_allowed);
|
|
dest_cpu = any_online_cpu(mask);
|
|
|
|
/* On any allowed CPU? */
|
|
if (dest_cpu == NR_CPUS)
|
|
dest_cpu = any_online_cpu(tsk->cpus_allowed);
|
|
|
|
/* No more Mr. Nice Guy. */
|
|
if (dest_cpu == NR_CPUS) {
|
|
tsk->cpus_allowed = cpuset_cpus_allowed(tsk);
|
|
dest_cpu = any_online_cpu(tsk->cpus_allowed);
|
|
|
|
/*
|
|
* Don't tell them about moving exiting tasks or
|
|
* kernel threads (both mm NULL), since they never
|
|
* leave kernel.
|
|
*/
|
|
if (tsk->mm && printk_ratelimit())
|
|
printk(KERN_INFO "process %d (%s) no "
|
|
"longer affine to cpu%d\n",
|
|
tsk->pid, tsk->comm, dead_cpu);
|
|
}
|
|
__migrate_task(tsk, dead_cpu, dest_cpu);
|
|
}
|
|
|
|
/*
|
|
* While a dead CPU has no uninterruptible tasks queued at this point,
|
|
* it might still have a nonzero ->nr_uninterruptible counter, because
|
|
* for performance reasons the counter is not stricly tracking tasks to
|
|
* their home CPUs. So we just add the counter to another CPU's counter,
|
|
* to keep the global sum constant after CPU-down:
|
|
*/
|
|
static void migrate_nr_uninterruptible(runqueue_t *rq_src)
|
|
{
|
|
runqueue_t *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL));
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
double_rq_lock(rq_src, rq_dest);
|
|
rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
|
|
rq_src->nr_uninterruptible = 0;
|
|
double_rq_unlock(rq_src, rq_dest);
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
/* Run through task list and migrate tasks from the dead cpu. */
|
|
static void migrate_live_tasks(int src_cpu)
|
|
{
|
|
struct task_struct *tsk, *t;
|
|
|
|
write_lock_irq(&tasklist_lock);
|
|
|
|
do_each_thread(t, tsk) {
|
|
if (tsk == current)
|
|
continue;
|
|
|
|
if (task_cpu(tsk) == src_cpu)
|
|
move_task_off_dead_cpu(src_cpu, tsk);
|
|
} while_each_thread(t, tsk);
|
|
|
|
write_unlock_irq(&tasklist_lock);
|
|
}
|
|
|
|
/* Schedules idle task to be the next runnable task on current CPU.
|
|
* It does so by boosting its priority to highest possible and adding it to
|
|
* the _front_ of runqueue. Used by CPU offline code.
|
|
*/
|
|
void sched_idle_next(void)
|
|
{
|
|
int cpu = smp_processor_id();
|
|
runqueue_t *rq = this_rq();
|
|
struct task_struct *p = rq->idle;
|
|
unsigned long flags;
|
|
|
|
/* cpu has to be offline */
|
|
BUG_ON(cpu_online(cpu));
|
|
|
|
/* Strictly not necessary since rest of the CPUs are stopped by now
|
|
* and interrupts disabled on current cpu.
|
|
*/
|
|
spin_lock_irqsave(&rq->lock, flags);
|
|
|
|
__setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
|
|
/* Add idle task to _front_ of it's priority queue */
|
|
__activate_idle_task(p, rq);
|
|
|
|
spin_unlock_irqrestore(&rq->lock, flags);
|
|
}
|
|
|
|
/* Ensures that the idle task is using init_mm right before its cpu goes
|
|
* offline.
|
|
*/
|
|
void idle_task_exit(void)
|
|
{
|
|
struct mm_struct *mm = current->active_mm;
|
|
|
|
BUG_ON(cpu_online(smp_processor_id()));
|
|
|
|
if (mm != &init_mm)
|
|
switch_mm(mm, &init_mm, current);
|
|
mmdrop(mm);
|
|
}
|
|
|
|
static void migrate_dead(unsigned int dead_cpu, task_t *tsk)
|
|
{
|
|
struct runqueue *rq = cpu_rq(dead_cpu);
|
|
|
|
/* Must be exiting, otherwise would be on tasklist. */
|
|
BUG_ON(tsk->exit_state != EXIT_ZOMBIE && tsk->exit_state != EXIT_DEAD);
|
|
|
|
/* Cannot have done final schedule yet: would have vanished. */
|
|
BUG_ON(tsk->flags & PF_DEAD);
|
|
|
|
get_task_struct(tsk);
|
|
|
|
/*
|
|
* Drop lock around migration; if someone else moves it,
|
|
* that's OK. No task can be added to this CPU, so iteration is
|
|
* fine.
|
|
*/
|
|
spin_unlock_irq(&rq->lock);
|
|
move_task_off_dead_cpu(dead_cpu, tsk);
|
|
spin_lock_irq(&rq->lock);
|
|
|
|
put_task_struct(tsk);
|
|
}
|
|
|
|
/* release_task() removes task from tasklist, so we won't find dead tasks. */
|
|
static void migrate_dead_tasks(unsigned int dead_cpu)
|
|
{
|
|
unsigned arr, i;
|
|
struct runqueue *rq = cpu_rq(dead_cpu);
|
|
|
|
for (arr = 0; arr < 2; arr++) {
|
|
for (i = 0; i < MAX_PRIO; i++) {
|
|
struct list_head *list = &rq->arrays[arr].queue[i];
|
|
while (!list_empty(list))
|
|
migrate_dead(dead_cpu,
|
|
list_entry(list->next, task_t,
|
|
run_list));
|
|
}
|
|
}
|
|
}
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
|
|
/*
|
|
* migration_call - callback that gets triggered when a CPU is added.
|
|
* Here we can start up the necessary migration thread for the new CPU.
|
|
*/
|
|
static int migration_call(struct notifier_block *nfb, unsigned long action,
|
|
void *hcpu)
|
|
{
|
|
int cpu = (long)hcpu;
|
|
struct task_struct *p;
|
|
struct runqueue *rq;
|
|
unsigned long flags;
|
|
|
|
switch (action) {
|
|
case CPU_UP_PREPARE:
|
|
p = kthread_create(migration_thread, hcpu, "migration/%d",cpu);
|
|
if (IS_ERR(p))
|
|
return NOTIFY_BAD;
|
|
p->flags |= PF_NOFREEZE;
|
|
kthread_bind(p, cpu);
|
|
/* Must be high prio: stop_machine expects to yield to it. */
|
|
rq = task_rq_lock(p, &flags);
|
|
__setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
|
|
task_rq_unlock(rq, &flags);
|
|
cpu_rq(cpu)->migration_thread = p;
|
|
break;
|
|
case CPU_ONLINE:
|
|
/* Strictly unneccessary, as first user will wake it. */
|
|
wake_up_process(cpu_rq(cpu)->migration_thread);
|
|
break;
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
case CPU_UP_CANCELED:
|
|
/* Unbind it from offline cpu so it can run. Fall thru. */
|
|
kthread_bind(cpu_rq(cpu)->migration_thread,smp_processor_id());
|
|
kthread_stop(cpu_rq(cpu)->migration_thread);
|
|
cpu_rq(cpu)->migration_thread = NULL;
|
|
break;
|
|
case CPU_DEAD:
|
|
migrate_live_tasks(cpu);
|
|
rq = cpu_rq(cpu);
|
|
kthread_stop(rq->migration_thread);
|
|
rq->migration_thread = NULL;
|
|
/* Idle task back to normal (off runqueue, low prio) */
|
|
rq = task_rq_lock(rq->idle, &flags);
|
|
deactivate_task(rq->idle, rq);
|
|
rq->idle->static_prio = MAX_PRIO;
|
|
__setscheduler(rq->idle, SCHED_NORMAL, 0);
|
|
migrate_dead_tasks(cpu);
|
|
task_rq_unlock(rq, &flags);
|
|
migrate_nr_uninterruptible(rq);
|
|
BUG_ON(rq->nr_running != 0);
|
|
|
|
/* No need to migrate the tasks: it was best-effort if
|
|
* they didn't do lock_cpu_hotplug(). Just wake up
|
|
* the requestors. */
|
|
spin_lock_irq(&rq->lock);
|
|
while (!list_empty(&rq->migration_queue)) {
|
|
migration_req_t *req;
|
|
req = list_entry(rq->migration_queue.next,
|
|
migration_req_t, list);
|
|
BUG_ON(req->type != REQ_MOVE_TASK);
|
|
list_del_init(&req->list);
|
|
complete(&req->done);
|
|
}
|
|
spin_unlock_irq(&rq->lock);
|
|
break;
|
|
#endif
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
/* Register at highest priority so that task migration (migrate_all_tasks)
|
|
* happens before everything else.
|
|
*/
|
|
static struct notifier_block __devinitdata migration_notifier = {
|
|
.notifier_call = migration_call,
|
|
.priority = 10
|
|
};
|
|
|
|
int __init migration_init(void)
|
|
{
|
|
void *cpu = (void *)(long)smp_processor_id();
|
|
/* Start one for boot CPU. */
|
|
migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
|
|
migration_call(&migration_notifier, CPU_ONLINE, cpu);
|
|
register_cpu_notifier(&migration_notifier);
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_SMP
|
|
#define SCHED_DOMAIN_DEBUG
|
|
#ifdef SCHED_DOMAIN_DEBUG
|
|
static void sched_domain_debug(struct sched_domain *sd, int cpu)
|
|
{
|
|
int level = 0;
|
|
|
|
printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
|
|
|
|
do {
|
|
int i;
|
|
char str[NR_CPUS];
|
|
struct sched_group *group = sd->groups;
|
|
cpumask_t groupmask;
|
|
|
|
cpumask_scnprintf(str, NR_CPUS, sd->span);
|
|
cpus_clear(groupmask);
|
|
|
|
printk(KERN_DEBUG);
|
|
for (i = 0; i < level + 1; i++)
|
|
printk(" ");
|
|
printk("domain %d: ", level);
|
|
|
|
if (!(sd->flags & SD_LOAD_BALANCE)) {
|
|
printk("does not load-balance\n");
|
|
if (sd->parent)
|
|
printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain has parent");
|
|
break;
|
|
}
|
|
|
|
printk("span %s\n", str);
|
|
|
|
if (!cpu_isset(cpu, sd->span))
|
|
printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
|
|
if (!cpu_isset(cpu, group->cpumask))
|
|
printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
|
|
|
|
printk(KERN_DEBUG);
|
|
for (i = 0; i < level + 2; i++)
|
|
printk(" ");
|
|
printk("groups:");
|
|
do {
|
|
if (!group) {
|
|
printk("\n");
|
|
printk(KERN_ERR "ERROR: group is NULL\n");
|
|
break;
|
|
}
|
|
|
|
if (!group->cpu_power) {
|
|
printk("\n");
|
|
printk(KERN_ERR "ERROR: domain->cpu_power not set\n");
|
|
}
|
|
|
|
if (!cpus_weight(group->cpumask)) {
|
|
printk("\n");
|
|
printk(KERN_ERR "ERROR: empty group\n");
|
|
}
|
|
|
|
if (cpus_intersects(groupmask, group->cpumask)) {
|
|
printk("\n");
|
|
printk(KERN_ERR "ERROR: repeated CPUs\n");
|
|
}
|
|
|
|
cpus_or(groupmask, groupmask, group->cpumask);
|
|
|
|
cpumask_scnprintf(str, NR_CPUS, group->cpumask);
|
|
printk(" %s", str);
|
|
|
|
group = group->next;
|
|
} while (group != sd->groups);
|
|
printk("\n");
|
|
|
|
if (!cpus_equal(sd->span, groupmask))
|
|
printk(KERN_ERR "ERROR: groups don't span domain->span\n");
|
|
|
|
level++;
|
|
sd = sd->parent;
|
|
|
|
if (sd) {
|
|
if (!cpus_subset(groupmask, sd->span))
|
|
printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
|
|
}
|
|
|
|
} while (sd);
|
|
}
|
|
#else
|
|
#define sched_domain_debug(sd, cpu) {}
|
|
#endif
|
|
|
|
/*
|
|
* Attach the domain 'sd' to 'cpu' as its base domain. Callers must
|
|
* hold the hotplug lock.
|
|
*/
|
|
void __devinit cpu_attach_domain(struct sched_domain *sd, int cpu)
|
|
{
|
|
migration_req_t req;
|
|
unsigned long flags;
|
|
runqueue_t *rq = cpu_rq(cpu);
|
|
int local = 1;
|
|
|
|
sched_domain_debug(sd, cpu);
|
|
|
|
spin_lock_irqsave(&rq->lock, flags);
|
|
|
|
if (cpu == smp_processor_id() || !cpu_online(cpu)) {
|
|
rq->sd = sd;
|
|
} else {
|
|
init_completion(&req.done);
|
|
req.type = REQ_SET_DOMAIN;
|
|
req.sd = sd;
|
|
list_add(&req.list, &rq->migration_queue);
|
|
local = 0;
|
|
}
|
|
|
|
spin_unlock_irqrestore(&rq->lock, flags);
|
|
|
|
if (!local) {
|
|
wake_up_process(rq->migration_thread);
|
|
wait_for_completion(&req.done);
|
|
}
|
|
}
|
|
|
|
/* cpus with isolated domains */
|
|
cpumask_t __devinitdata cpu_isolated_map = CPU_MASK_NONE;
|
|
|
|
/* Setup the mask of cpus configured for isolated domains */
|
|
static int __init isolated_cpu_setup(char *str)
|
|
{
|
|
int ints[NR_CPUS], i;
|
|
|
|
str = get_options(str, ARRAY_SIZE(ints), ints);
|
|
cpus_clear(cpu_isolated_map);
|
|
for (i = 1; i <= ints[0]; i++)
|
|
if (ints[i] < NR_CPUS)
|
|
cpu_set(ints[i], cpu_isolated_map);
|
|
return 1;
|
|
}
|
|
|
|
__setup ("isolcpus=", isolated_cpu_setup);
|
|
|
|
/*
|
|
* init_sched_build_groups takes an array of groups, the cpumask we wish
|
|
* to span, and a pointer to a function which identifies what group a CPU
|
|
* belongs to. The return value of group_fn must be a valid index into the
|
|
* groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we
|
|
* keep track of groups covered with a cpumask_t).
|
|
*
|
|
* init_sched_build_groups will build a circular linked list of the groups
|
|
* covered by the given span, and will set each group's ->cpumask correctly,
|
|
* and ->cpu_power to 0.
|
|
*/
|
|
void __devinit init_sched_build_groups(struct sched_group groups[],
|
|
cpumask_t span, int (*group_fn)(int cpu))
|
|
{
|
|
struct sched_group *first = NULL, *last = NULL;
|
|
cpumask_t covered = CPU_MASK_NONE;
|
|
int i;
|
|
|
|
for_each_cpu_mask(i, span) {
|
|
int group = group_fn(i);
|
|
struct sched_group *sg = &groups[group];
|
|
int j;
|
|
|
|
if (cpu_isset(i, covered))
|
|
continue;
|
|
|
|
sg->cpumask = CPU_MASK_NONE;
|
|
sg->cpu_power = 0;
|
|
|
|
for_each_cpu_mask(j, span) {
|
|
if (group_fn(j) != group)
|
|
continue;
|
|
|
|
cpu_set(j, covered);
|
|
cpu_set(j, sg->cpumask);
|
|
}
|
|
if (!first)
|
|
first = sg;
|
|
if (last)
|
|
last->next = sg;
|
|
last = sg;
|
|
}
|
|
last->next = first;
|
|
}
|
|
|
|
|
|
#ifdef ARCH_HAS_SCHED_DOMAIN
|
|
extern void __devinit arch_init_sched_domains(void);
|
|
extern void __devinit arch_destroy_sched_domains(void);
|
|
#else
|
|
#ifdef CONFIG_SCHED_SMT
|
|
static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
|
|
static struct sched_group sched_group_cpus[NR_CPUS];
|
|
static int __devinit cpu_to_cpu_group(int cpu)
|
|
{
|
|
return cpu;
|
|
}
|
|
#endif
|
|
|
|
static DEFINE_PER_CPU(struct sched_domain, phys_domains);
|
|
static struct sched_group sched_group_phys[NR_CPUS];
|
|
static int __devinit cpu_to_phys_group(int cpu)
|
|
{
|
|
#ifdef CONFIG_SCHED_SMT
|
|
return first_cpu(cpu_sibling_map[cpu]);
|
|
#else
|
|
return cpu;
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
|
|
static DEFINE_PER_CPU(struct sched_domain, node_domains);
|
|
static struct sched_group sched_group_nodes[MAX_NUMNODES];
|
|
static int __devinit cpu_to_node_group(int cpu)
|
|
{
|
|
return cpu_to_node(cpu);
|
|
}
|
|
#endif
|
|
|
|
#if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA)
|
|
/*
|
|
* The domains setup code relies on siblings not spanning
|
|
* multiple nodes. Make sure the architecture has a proper
|
|
* siblings map:
|
|
*/
|
|
static void check_sibling_maps(void)
|
|
{
|
|
int i, j;
|
|
|
|
for_each_online_cpu(i) {
|
|
for_each_cpu_mask(j, cpu_sibling_map[i]) {
|
|
if (cpu_to_node(i) != cpu_to_node(j)) {
|
|
printk(KERN_INFO "warning: CPU %d siblings map "
|
|
"to different node - isolating "
|
|
"them.\n", i);
|
|
cpu_sibling_map[i] = cpumask_of_cpu(i);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Set up scheduler domains and groups. Callers must hold the hotplug lock.
|
|
*/
|
|
static void __devinit arch_init_sched_domains(void)
|
|
{
|
|
int i;
|
|
cpumask_t cpu_default_map;
|
|
|
|
#if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA)
|
|
check_sibling_maps();
|
|
#endif
|
|
/*
|
|
* Setup mask for cpus without special case scheduling requirements.
|
|
* For now this just excludes isolated cpus, but could be used to
|
|
* exclude other special cases in the future.
|
|
*/
|
|
cpus_complement(cpu_default_map, cpu_isolated_map);
|
|
cpus_and(cpu_default_map, cpu_default_map, cpu_online_map);
|
|
|
|
/*
|
|
* Set up domains. Isolated domains just stay on the dummy domain.
|
|
*/
|
|
for_each_cpu_mask(i, cpu_default_map) {
|
|
int group;
|
|
struct sched_domain *sd = NULL, *p;
|
|
cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
|
|
|
|
cpus_and(nodemask, nodemask, cpu_default_map);
|
|
|
|
#ifdef CONFIG_NUMA
|
|
sd = &per_cpu(node_domains, i);
|
|
group = cpu_to_node_group(i);
|
|
*sd = SD_NODE_INIT;
|
|
sd->span = cpu_default_map;
|
|
sd->groups = &sched_group_nodes[group];
|
|
#endif
|
|
|
|
p = sd;
|
|
sd = &per_cpu(phys_domains, i);
|
|
group = cpu_to_phys_group(i);
|
|
*sd = SD_CPU_INIT;
|
|
sd->span = nodemask;
|
|
sd->parent = p;
|
|
sd->groups = &sched_group_phys[group];
|
|
|
|
#ifdef CONFIG_SCHED_SMT
|
|
p = sd;
|
|
sd = &per_cpu(cpu_domains, i);
|
|
group = cpu_to_cpu_group(i);
|
|
*sd = SD_SIBLING_INIT;
|
|
sd->span = cpu_sibling_map[i];
|
|
cpus_and(sd->span, sd->span, cpu_default_map);
|
|
sd->parent = p;
|
|
sd->groups = &sched_group_cpus[group];
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_SCHED_SMT
|
|
/* Set up CPU (sibling) groups */
|
|
for_each_online_cpu(i) {
|
|
cpumask_t this_sibling_map = cpu_sibling_map[i];
|
|
cpus_and(this_sibling_map, this_sibling_map, cpu_default_map);
|
|
if (i != first_cpu(this_sibling_map))
|
|
continue;
|
|
|
|
init_sched_build_groups(sched_group_cpus, this_sibling_map,
|
|
&cpu_to_cpu_group);
|
|
}
|
|
#endif
|
|
|
|
/* Set up physical groups */
|
|
for (i = 0; i < MAX_NUMNODES; i++) {
|
|
cpumask_t nodemask = node_to_cpumask(i);
|
|
|
|
cpus_and(nodemask, nodemask, cpu_default_map);
|
|
if (cpus_empty(nodemask))
|
|
continue;
|
|
|
|
init_sched_build_groups(sched_group_phys, nodemask,
|
|
&cpu_to_phys_group);
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
/* Set up node groups */
|
|
init_sched_build_groups(sched_group_nodes, cpu_default_map,
|
|
&cpu_to_node_group);
|
|
#endif
|
|
|
|
/* Calculate CPU power for physical packages and nodes */
|
|
for_each_cpu_mask(i, cpu_default_map) {
|
|
int power;
|
|
struct sched_domain *sd;
|
|
#ifdef CONFIG_SCHED_SMT
|
|
sd = &per_cpu(cpu_domains, i);
|
|
power = SCHED_LOAD_SCALE;
|
|
sd->groups->cpu_power = power;
|
|
#endif
|
|
|
|
sd = &per_cpu(phys_domains, i);
|
|
power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE *
|
|
(cpus_weight(sd->groups->cpumask)-1) / 10;
|
|
sd->groups->cpu_power = power;
|
|
|
|
#ifdef CONFIG_NUMA
|
|
if (i == first_cpu(sd->groups->cpumask)) {
|
|
/* Only add "power" once for each physical package. */
|
|
sd = &per_cpu(node_domains, i);
|
|
sd->groups->cpu_power += power;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/* Attach the domains */
|
|
for_each_online_cpu(i) {
|
|
struct sched_domain *sd;
|
|
#ifdef CONFIG_SCHED_SMT
|
|
sd = &per_cpu(cpu_domains, i);
|
|
#else
|
|
sd = &per_cpu(phys_domains, i);
|
|
#endif
|
|
cpu_attach_domain(sd, i);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
static void __devinit arch_destroy_sched_domains(void)
|
|
{
|
|
/* Do nothing: everything is statically allocated. */
|
|
}
|
|
#endif
|
|
|
|
#endif /* ARCH_HAS_SCHED_DOMAIN */
|
|
|
|
/*
|
|
* Initial dummy domain for early boot and for hotplug cpu. Being static,
|
|
* it is initialized to zero, so all balancing flags are cleared which is
|
|
* what we want.
|
|
*/
|
|
static struct sched_domain sched_domain_dummy;
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
/*
|
|
* Force a reinitialization of the sched domains hierarchy. The domains
|
|
* and groups cannot be updated in place without racing with the balancing
|
|
* code, so we temporarily attach all running cpus to a "dummy" domain
|
|
* which will prevent rebalancing while the sched domains are recalculated.
|
|
*/
|
|
static int update_sched_domains(struct notifier_block *nfb,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
int i;
|
|
|
|
switch (action) {
|
|
case CPU_UP_PREPARE:
|
|
case CPU_DOWN_PREPARE:
|
|
for_each_online_cpu(i)
|
|
cpu_attach_domain(&sched_domain_dummy, i);
|
|
arch_destroy_sched_domains();
|
|
return NOTIFY_OK;
|
|
|
|
case CPU_UP_CANCELED:
|
|
case CPU_DOWN_FAILED:
|
|
case CPU_ONLINE:
|
|
case CPU_DEAD:
|
|
/*
|
|
* Fall through and re-initialise the domains.
|
|
*/
|
|
break;
|
|
default:
|
|
return NOTIFY_DONE;
|
|
}
|
|
|
|
/* The hotplug lock is already held by cpu_up/cpu_down */
|
|
arch_init_sched_domains();
|
|
|
|
return NOTIFY_OK;
|
|
}
|
|
#endif
|
|
|
|
void __init sched_init_smp(void)
|
|
{
|
|
lock_cpu_hotplug();
|
|
arch_init_sched_domains();
|
|
unlock_cpu_hotplug();
|
|
/* XXX: Theoretical race here - CPU may be hotplugged now */
|
|
hotcpu_notifier(update_sched_domains, 0);
|
|
}
|
|
#else
|
|
void __init sched_init_smp(void)
|
|
{
|
|
}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
int in_sched_functions(unsigned long addr)
|
|
{
|
|
/* Linker adds these: start and end of __sched functions */
|
|
extern char __sched_text_start[], __sched_text_end[];
|
|
return in_lock_functions(addr) ||
|
|
(addr >= (unsigned long)__sched_text_start
|
|
&& addr < (unsigned long)__sched_text_end);
|
|
}
|
|
|
|
void __init sched_init(void)
|
|
{
|
|
runqueue_t *rq;
|
|
int i, j, k;
|
|
|
|
for (i = 0; i < NR_CPUS; i++) {
|
|
prio_array_t *array;
|
|
|
|
rq = cpu_rq(i);
|
|
spin_lock_init(&rq->lock);
|
|
rq->active = rq->arrays;
|
|
rq->expired = rq->arrays + 1;
|
|
rq->best_expired_prio = MAX_PRIO;
|
|
|
|
#ifdef CONFIG_SMP
|
|
rq->sd = &sched_domain_dummy;
|
|
rq->cpu_load = 0;
|
|
rq->active_balance = 0;
|
|
rq->push_cpu = 0;
|
|
rq->migration_thread = NULL;
|
|
INIT_LIST_HEAD(&rq->migration_queue);
|
|
#endif
|
|
atomic_set(&rq->nr_iowait, 0);
|
|
|
|
for (j = 0; j < 2; j++) {
|
|
array = rq->arrays + j;
|
|
for (k = 0; k < MAX_PRIO; k++) {
|
|
INIT_LIST_HEAD(array->queue + k);
|
|
__clear_bit(k, array->bitmap);
|
|
}
|
|
// delimiter for bitsearch
|
|
__set_bit(MAX_PRIO, array->bitmap);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The boot idle thread does lazy MMU switching as well:
|
|
*/
|
|
atomic_inc(&init_mm.mm_count);
|
|
enter_lazy_tlb(&init_mm, current);
|
|
|
|
/*
|
|
* Make us the idle thread. Technically, schedule() should not be
|
|
* called from this thread, however somewhere below it might be,
|
|
* but because we are the idle thread, we just pick up running again
|
|
* when this runqueue becomes "idle".
|
|
*/
|
|
init_idle(current, smp_processor_id());
|
|
}
|
|
|
|
#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
|
|
void __might_sleep(char *file, int line)
|
|
{
|
|
#if defined(in_atomic)
|
|
static unsigned long prev_jiffy; /* ratelimiting */
|
|
|
|
if ((in_atomic() || irqs_disabled()) &&
|
|
system_state == SYSTEM_RUNNING && !oops_in_progress) {
|
|
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
|
|
return;
|
|
prev_jiffy = jiffies;
|
|
printk(KERN_ERR "Debug: sleeping function called from invalid"
|
|
" context at %s:%d\n", file, line);
|
|
printk("in_atomic():%d, irqs_disabled():%d\n",
|
|
in_atomic(), irqs_disabled());
|
|
dump_stack();
|
|
}
|
|
#endif
|
|
}
|
|
EXPORT_SYMBOL(__might_sleep);
|
|
#endif
|
|
|
|
#ifdef CONFIG_MAGIC_SYSRQ
|
|
void normalize_rt_tasks(void)
|
|
{
|
|
struct task_struct *p;
|
|
prio_array_t *array;
|
|
unsigned long flags;
|
|
runqueue_t *rq;
|
|
|
|
read_lock_irq(&tasklist_lock);
|
|
for_each_process (p) {
|
|
if (!rt_task(p))
|
|
continue;
|
|
|
|
rq = task_rq_lock(p, &flags);
|
|
|
|
array = p->array;
|
|
if (array)
|
|
deactivate_task(p, task_rq(p));
|
|
__setscheduler(p, SCHED_NORMAL, 0);
|
|
if (array) {
|
|
__activate_task(p, task_rq(p));
|
|
resched_task(rq->curr);
|
|
}
|
|
|
|
task_rq_unlock(rq, &flags);
|
|
}
|
|
read_unlock_irq(&tasklist_lock);
|
|
}
|
|
|
|
#endif /* CONFIG_MAGIC_SYSRQ */
|