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: Christoph 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 158ca64..d57a091 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -437,33 +437,29 @@
* 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;
+ struct per_cpu_pageset __percpu *p = zone->pageset;
- p = per_cpu_ptr(zone->pageset, cpu);
+ for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
+ int v;
- for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
- if (p->vm_stat_diff[i]) {
- unsigned long flags;
- int v;
+ v = this_cpu_xchg(p->vm_stat_diff[i], 0);
+ if (v) {
- local_irq_save(flags);
- v = p->vm_stat_diff[i];
- p->vm_stat_diff[i] = 0;
- local_irq_restore(flags);
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 @@
* 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 @@
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));
}