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authorDave Hansen <dave@linux.vnet.ibm.com>2014-04-03 17:48:19 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-03 19:21:04 -0400
commit5509a5d27b971a90b940e148ca9ca53312e4fa7a (patch)
treea05845240563a79deafc3350e6409c6b3058e0f2 /mm/vmstat.c
parent67f9fd91f93c582b7de2ab9325b6e179db77e4d5 (diff)
drop_caches: add some documentation and info message
There is plenty of anecdotal evidence and a load of blog posts suggesting that using "drop_caches" periodically keeps your system running in "tip top shape". Perhaps adding some kernel documentation will increase the amount of accurate data on its use. If we are not shrinking caches effectively, then we have real bugs. Using drop_caches will simply mask the bugs and make them harder to find, but certainly does not fix them, nor is it an appropriate "workaround" to limit the size of the caches. On the contrary, there have been bug reports on issues that turned out to be misguided use of cache dropping. Dropping caches is a very drastic and disruptive operation that is good for debugging and running tests, but if it creates bug reports from production use, kernel developers should be aware of its use. Add a bit more documentation about it, a syslog message to track down abusers, and vmstat drop counters to help analyze problem reports. [akpm@linux-foundation.org: checkpatch fixes] [hannes@cmpxchg.org: add runtime suppression control] Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmstat.c')
-rw-r--r--mm/vmstat.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c
index f3155d51acfd..197b4c4a9587 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -813,6 +813,9 @@ const char * const vmstat_text[] = {
813 813
814 "pgrotated", 814 "pgrotated",
815 815
816 "drop_pagecache",
817 "drop_slab",
818
816#ifdef CONFIG_NUMA_BALANCING 819#ifdef CONFIG_NUMA_BALANCING
817 "numa_pte_updates", 820 "numa_pte_updates",
818 "numa_huge_pte_updates", 821 "numa_huge_pte_updates",