memcg: change memcg_oom_mutex to spinlock
commit1af8efe965676ab30d6c8a5b1fccc9229f339a3b
authorMichal Hocko <mhocko@suse.cz>
Tue, 26 Jul 2011 23:08:24 +0000 (26 16:08 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 26 Jul 2011 23:49:42 +0000 (26 16:49 -0700)
tree832cfd92cae498d9af1687bccc77344143df97a1
parent79dfdaccd1d5b40ff7cf4a35a0e63696ebb78b4d
memcg: change memcg_oom_mutex to spinlock

memcg_oom_mutex is used to protect memcg OOM path and eventfd interface
for oom_control.  None of the critical sections which it protects sleep
(eventfd_signal works from atomic context and the rest are simple linked
list resp.  oom_lock atomic operations).

Mutex is also too heavyweight for those code paths because it triggers a
lot of scheduling.  It also makes makes convoying effects more visible
when we have a big number of oom killing because we take the lock
mutliple times during mem_cgroup_handle_oom so we have multiple places
where many processes can sleep.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/memcontrol.c