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authorGilad Ben-Yossef <gilad@benyossef.com>2013-06-26 17:24:59 +0100
committerJon Medhurst <tixy@linaro.org>2013-07-17 11:30:48 +0100
commit7d252cd22a3f6cb459e8b012912dfd258157f7df (patch)
tree4560f67a5dd4a77f11ea5d1ac6ef91ff29eda58f /include/linux
parent1dfb365825bf076bc089b8198667c384a8ab89d4 (diff)
downloadvexpress-lsk-7d252cd22a3f6cb459e8b012912dfd258157f7df.tar.gz
mm: make vmstat_update periodic run conditional
vmstat_update runs every second from the work queue to update statistics and drain per cpu pages back into the global page allocator. This is useful in most circumstances but is wasteful if the CPU doesn't actually make any VM activity. This can happen in the situtation that the CPU is idle or running a CPU bound long term task (e.g. CPU isolation), in which case the periodic vmstate_update timer needlessly itnerrupts the CPU. This patch tries to make vmstat_update schedule itself for the next round only if there was any work for it to do in the previous run. The assumption is that if for a whole second we didn't see any VM activity it is reasnoable to assume that the CPU is not using the VM because it is idle or runs a long term single CPU bound task. A new single unbound system work queue item is scheduled periodically to monitor CPUs that have their vmstat_update work stopped and re-schedule them if VM activity is detected. Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Tejun Heo <tj@kernel.org> CC: John Stultz <johnstul@us.ibm.com> CC: Andrew Morton <akpm@linux-foundation.org> CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> CC: Mel Gorman <mel@csn.ul.ie> CC: Mike Frysinger <vapier@gentoo.org> CC: David Rientjes <rientjes@google.com> CC: Hugh Dickins <hughd@google.com> CC: Minchan Kim <minchan.kim@gmail.com> CC: Konstantin Khlebnikov <khlebnikov@openvz.org> CC: Christoph Lameter <cl@linux.com> CC: Chris Metcalf <cmetcalf@tilera.com> CC: Hakan Akkan <hakanakkan@gmail.com> CC: Max Krasnyansky <maxk@qualcomm.com> CC: Frederic Weisbecker <fweisbec@gmail.com> CC: linux-kernel@vger.kernel.org CC: linux-mm@kvack.org
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/vmstat.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index c586679b6fe..a30ab7910ff 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);
+bool refresh_cpu_vm_stats(int);
void refresh_zone_stat_thresholds(void);
void drain_zonestat(struct zone *zone, struct per_cpu_pageset *);