From 2bb921e526656556e68f99f5f15a4a1bf2691844 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Wed, 11 Sep 2013 14:21:30 -0700 Subject: vmstat: create separate function to fold per cpu diffs into local counters The main idea behind this patchset is to reduce the vmstat update overhead by avoiding interrupt enable/disable and the use of per cpu atomics. This patch (of 3): It is better to have a separate folding function because refresh_cpu_vm_stats() also does other things like expire pages in the page allocator caches. If we have a separate function then refresh_cpu_vm_stats() is only called from the local cpu which allows additional optimizations. The folding function is only called when a cpu is being downed and therefore no other processor will be accessing the counters. Also simplifies synchronization. [akpm@linux-foundation.org: fix UP build] 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 --- include/linux/vmstat.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h index c586679b6fef..502767f4e4d4 100644 --- a/include/linux/vmstat.h +++ b/include/linux/vmstat.h @@ -198,7 +198,7 @@ extern void __inc_zone_state(struct zone *, enum zone_stat_item); extern void dec_zone_state(struct zone *, enum zone_stat_item); extern void __dec_zone_state(struct zone *, enum zone_stat_item); -void refresh_cpu_vm_stats(int); +void cpu_vm_stats_fold(int cpu); void refresh_zone_stat_thresholds(void); void drain_zonestat(struct zone *zone, struct per_cpu_pageset *); @@ -255,6 +255,7 @@ static inline void __dec_zone_page_state(struct page *page, static inline void refresh_cpu_vm_stats(int cpu) { } static inline void refresh_zone_stat_thresholds(void) { } +static inline void cpu_vm_stats_fold(int cpu) { } static inline void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset) { } -- cgit v1.2.3