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mm: page_alloc: use jump labels to avoid checking number_of_cpusets 

If cpusets are not in use then we still check a global variable on every
page allocation.  Use jump labels to avoid the overhead.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2014-06-04 16:10:08 -07:00 committed by Linus Torvalds
parent ea5e9539ab
commit 664eeddeef
3 changed files with 32 additions and 14 deletions
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29
include/linux/cpuset.h
View File

@ -12,10 +12,31 @@
#include <linux/cpumask.h>
#include <linux/nodemask.h>
#include <linux/mm.h>
#include <linux/jump_label.h>
#ifdef CONFIG_CPUSETS
extern int number_of_cpusets; /* How many cpusets are defined in system? */
extern struct static_key cpusets_enabled_key;
static inline bool cpusets_enabled(void)
{
return static_key_false(&cpusets_enabled_key);
}
static inline int nr_cpusets(void)
{
/* jump label reference count + the top-level cpuset */
return static_key_count(&cpusets_enabled_key) + 1;
}
static inline void cpuset_inc(void)
{
static_key_slow_inc(&cpusets_enabled_key);
}
static inline void cpuset_dec(void)
{
static_key_slow_dec(&cpusets_enabled_key);
}
extern int cpuset_init(void);
extern void cpuset_init_smp(void);
@ -32,13 +53,13 @@ extern int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask);
static inline int cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
{
return number_of_cpusets <= 1 ||
return nr_cpusets() <= 1 ||
__cpuset_node_allowed_softwall(node, gfp_mask);
}
static inline int cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
{
return number_of_cpusets <= 1 ||
return nr_cpusets() <= 1 ||
__cpuset_node_allowed_hardwall(node, gfp_mask);
}
@ -124,6 +145,8 @@ static inline void set_mems_allowed(nodemask_t nodemask)
#else /* !CONFIG_CPUSETS */
static inline bool cpusets_enabled(void) { return false; }
static inline int cpuset_init(void) { return 0; }
static inline void cpuset_init_smp(void) {}

14
kernel/cpuset.c
View File

@ -61,12 +61,7 @@
#include <linux/cgroup.h>
#include <linux/wait.h>
/*
* Tracks how many cpusets are currently defined in system.
* When there is only one cpuset (the root cpuset) we can
* short circuit some hooks.
*/
int number_of_cpusets __read_mostly;
struct static_key cpusets_enabled_key __read_mostly = STATIC_KEY_INIT_FALSE;
/* See "Frequency meter" comments, below. */
@ -611,7 +606,7 @@ static int generate_sched_domains(cpumask_var_t **domains,
goto done;
}
csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
csa = kmalloc(nr_cpusets() * sizeof(cp), GFP_KERNEL);
if (!csa)
goto done;
csn = 0;
@ -1888,7 +1883,7 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
if (is_spread_slab(parent))
set_bit(CS_SPREAD_SLAB, &cs->flags);
number_of_cpusets++;
cpuset_inc();
if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
goto out_unlock;
@ -1939,7 +1934,7 @@ static void cpuset_css_offline(struct cgroup_subsys_state *css)
if (is_sched_load_balance(cs))
update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
number_of_cpusets--;
cpuset_dec();
clear_bit(CS_ONLINE, &cs->flags);
mutex_unlock(&cpuset_mutex);
@ -1992,7 +1987,6 @@ int __init cpuset_init(void)
if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
BUG();
number_of_cpusets = 1;
return 0;
}

3
mm/page_alloc.c
View File

@ -1921,7 +1921,8 @@ get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,
if (IS_ENABLED(CONFIG_NUMA) && zlc_active &&
!zlc_zone_worth_trying(zonelist, z, allowednodes))
continue;
if ((alloc_flags & ALLOC_CPUSET) &&
if (cpusets_enabled() &&
(alloc_flags & ALLOC_CPUSET) &&
!cpuset_zone_allowed_softwall(zone, gfp_mask))
continue;
BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);