From fa13a5a1f25f671d084d8884be96fc48d9b68275 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Fri, 9 Nov 2007 22:39:38 +0100 Subject: [PATCH] sched: restore deterministic CPU accounting on powerpc Since powerpc started using CONFIG_GENERIC_CLOCKEVENTS, the deterministic CPU accounting (CONFIG_VIRT_CPU_ACCOUNTING) has been broken on powerpc, because we end up counting user time twice: once in timer_interrupt() and once in update_process_times(). This fixes the problem by pulling the code in update_process_times that updates utime and stime into a separate function called account_process_tick. If CONFIG_VIRT_CPU_ACCOUNTING is not defined, there is a version of account_process_tick in kernel/timer.c that simply accounts a whole tick to either utime or stime as before. If CONFIG_VIRT_CPU_ACCOUNTING is defined, then arch code gets to implement account_process_tick. This also lets us simplify the s390 code a bit; it means that the s390 timer interrupt can now call update_process_times even when CONFIG_VIRT_CPU_ACCOUNTING is turned on, and can just implement a suitable account_process_tick(). account_process_tick() now takes the task_struct * as an argument. Tested both with and without CONFIG_VIRT_CPU_ACCOUNTING. Signed-off-by: Paul Mackerras Signed-off-by: Ingo Molnar --- arch/powerpc/kernel/process.c | 2 +- arch/powerpc/kernel/time.c | 25 +------------------------ arch/s390/kernel/time.c | 4 ---- arch/s390/kernel/vtime.c | 8 +------- include/linux/sched.h | 1 + kernel/timer.c | 21 ++++++++++++++------- 6 files changed, 18 insertions(+), 43 deletions(-) diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index b9d88374f14f..41e13f4cc6e3 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -350,7 +350,7 @@ struct task_struct *__switch_to(struct task_struct *prev, local_irq_save(flags); account_system_vtime(current); - account_process_vtime(current); + account_process_tick(current, 0); calculate_steal_time(); last = _switch(old_thread, new_thread); diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 9eb3284deac4..a70dfb76d0a8 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -259,7 +259,7 @@ void account_system_vtime(struct task_struct *tsk) * user and system time records. * Must be called with interrupts disabled. */ -void account_process_vtime(struct task_struct *tsk) +void account_process_tick(struct task_struct *tsk, int user_tick) { cputime_t utime, utimescaled; @@ -274,18 +274,6 @@ void account_process_vtime(struct task_struct *tsk) account_user_time_scaled(tsk, utimescaled); } -static void account_process_time(struct pt_regs *regs) -{ - int cpu = smp_processor_id(); - - account_process_vtime(current); - run_local_timers(); - if (rcu_pending(cpu)) - rcu_check_callbacks(cpu, user_mode(regs)); - scheduler_tick(); - run_posix_cpu_timers(current); -} - /* * Stuff for accounting stolen time. */ @@ -375,7 +363,6 @@ static void snapshot_purr(void) #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */ #define calc_cputime_factors() -#define account_process_time(regs) update_process_times(user_mode(regs)) #define calculate_steal_time() do { } while (0) #endif @@ -599,16 +586,6 @@ void timer_interrupt(struct pt_regs * regs) get_lppaca()->int_dword.fields.decr_int = 0; #endif - /* - * We cannot disable the decrementer, so in the period - * between this cpu's being marked offline in cpu_online_map - * and calling stop-self, it is taking timer interrupts. - * Avoid calling into the scheduler rebalancing code if this - * is the case. - */ - if (!cpu_is_offline(cpu)) - account_process_time(regs); - if (evt->event_handler) evt->event_handler(evt); else diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index a963fe81359e..22b800ce2126 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -145,12 +145,8 @@ void account_ticks(u64 time) do_timer(ticks); #endif -#ifdef CONFIG_VIRT_CPU_ACCOUNTING - account_tick_vtime(current); -#else while (ticks--) update_process_times(user_mode(get_irq_regs())); -#endif s390_do_profile(); } diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c index 84ff78de6bac..c5f05b3fb2c3 100644 --- a/arch/s390/kernel/vtime.c +++ b/arch/s390/kernel/vtime.c @@ -32,7 +32,7 @@ static DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer); * Update process times based on virtual cpu times stored by entry.S * to the lowcore fields user_timer, system_timer & steal_clock. */ -void account_tick_vtime(struct task_struct *tsk) +void account_process_tick(struct task_struct *tsk, int user_tick) { cputime_t cputime; __u64 timer, clock; @@ -64,12 +64,6 @@ void account_tick_vtime(struct task_struct *tsk) S390_lowcore.steal_clock -= cputime << 12; account_steal_time(tsk, cputime); } - - run_local_timers(); - if (rcu_pending(smp_processor_id())) - rcu_check_callbacks(smp_processor_id(), rcu_user_flag); - scheduler_tick(); - run_posix_cpu_timers(tsk); } /* diff --git a/include/linux/sched.h b/include/linux/sched.h index 5457b6234e11..951759e30c09 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -254,6 +254,7 @@ long io_schedule_timeout(long timeout); extern void cpu_init (void); extern void trap_init(void); +extern void account_process_tick(struct task_struct *task, int user); extern void update_process_times(int user); extern void scheduler_tick(void); diff --git a/kernel/timer.c b/kernel/timer.c index 00e44e2afd67..a05817c021d6 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -817,6 +817,19 @@ unsigned long next_timer_interrupt(void) #endif +#ifndef CONFIG_VIRT_CPU_ACCOUNTING +void account_process_tick(struct task_struct *p, int user_tick) +{ + if (user_tick) { + account_user_time(p, jiffies_to_cputime(1)); + account_user_time_scaled(p, jiffies_to_cputime(1)); + } else { + account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1)); + account_system_time_scaled(p, jiffies_to_cputime(1)); + } +} +#endif + /* * Called from the timer interrupt handler to charge one tick to the current * process. user_tick is 1 if the tick is user time, 0 for system. @@ -827,13 +840,7 @@ void update_process_times(int user_tick) int cpu = smp_processor_id(); /* Note: this timer irq context must be accounted for as well. */ - if (user_tick) { - account_user_time(p, jiffies_to_cputime(1)); - account_user_time_scaled(p, jiffies_to_cputime(1)); - } else { - account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1)); - account_system_time_scaled(p, jiffies_to_cputime(1)); - } + account_process_tick(p, user_tick); run_local_timers(); if (rcu_pending(cpu)) rcu_check_callbacks(cpu, user_tick);