From fbc2edb05354480a88aa39db8a6acb5782fa1a1b Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Wed, 11 Sep 2013 14:21:32 -0700 Subject: [PATCH] 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 Cc: KOSAKI Motohiro CC: Tejun Heo Cc: Joonsoo Kim Cc: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmstat.c | 35 ++++++++++++++++------------------- 1 file changed, 16 insertions(+), 19 deletions(-) diff --git a/mm/vmstat.c b/mm/vmstat.c index 158ca6494bc6..d57a09143bf9 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -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; + 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 @@ 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)); } -- 2.20.1