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Commit fbc2edb0 authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
Browse files

vmstat: use this_cpu() to avoid irqon/off sequence in refresh_cpu_vm_stats 



Disabling interrupts repeatedly can be avoided in the inner loop if we use
a this_cpu operation.

Signed-off-by: default avatarChristoph Lameter <cl@linux.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Tejun Heo <tj@kernel.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4edb0748

mm/vmstat.c

+16 −19
Original line number Diff line number Diff line
@@ -437,33 +437,29 @@ static inline void fold_diff(int *diff) 
 * with the global counters. These could cause remote node cache line

 * bouncing and will have to be only done when necessary.

 */

static void refresh_cpu_vm_stats(int cpu)

static void refresh_cpu_vm_stats(void)

{

	struct zone *zone;

	int i;

	int global_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };



	for_each_populated_zone(zone) {

		struct per_cpu_pageset *p;



		p = per_cpu_ptr(zone->pageset, cpu);

		struct per_cpu_pageset __percpu *p = zone->pageset;



		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)

			if (p->vm_stat_diff[i]) {

				unsigned long flags;

		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {

			int v;



				local_irq_save(flags);

				v = p->vm_stat_diff[i];

				p->vm_stat_diff[i] = 0;

				local_irq_restore(flags);

			v = this_cpu_xchg(p->vm_stat_diff[i], 0);

			if (v) {



				atomic_long_add(v, &zone->vm_stat[i]);

				global_diff[i] += v;

#ifdef CONFIG_NUMA

				/* 3 seconds idle till flush */

				p->expire = 3;

				__this_cpu_write(p->expire, 3);

#endif

			}

		}

		cond_resched();

#ifdef CONFIG_NUMA

		/*
@@ -473,23 +469,24 @@ static void refresh_cpu_vm_stats(int cpu) 
		 * Check if there are pages remaining in this pageset

		 * if not then there is nothing to expire.

		 */

		if (!p->expire || !p->pcp.count)

		if (!__this_cpu_read(p->expire) ||

			       !__this_cpu_read(p->pcp.count))

			continue;



		/*

		 * We never drain zones local to this processor.

		 */

		if (zone_to_nid(zone) == numa_node_id()) {

			p->expire = 0;

			__this_cpu_write(p->expire, 0);

			continue;

		}



		p->expire--;

		if (p->expire)



		if (__this_cpu_dec_return(p->expire))

			continue;



		if (p->pcp.count)

			drain_zone_pages(zone, &p->pcp);

		if (__this_cpu_read(p->pcp.count))

			drain_zone_pages(zone, __this_cpu_ptr(&p->pcp));

#endif

	}

	fold_diff(global_diff);
@@ -1216,7 +1213,7 @@ int sysctl_stat_interval __read_mostly = HZ; 


static void vmstat_update(struct work_struct *w)

{

	refresh_cpu_vm_stats(smp_processor_id());

	refresh_cpu_vm_stats();

	schedule_delayed_work(&__get_cpu_var(vmstat_work),

		round_jiffies_relative(sysctl_stat_interval));

}