Re: [PATCH 2/2] memcg: change memcg_oom_mutex to spinlock
From: Michal Hocko
Date: Wed Jul 20 2011 - 03:01:12 EST
On Wed 20-07-11 14:55:53, KAMEZAWA Hiroyuki wrote:
> On Thu, 14 Jul 2011 17:29:51 +0200
> Michal Hocko <mhocko@xxxxxxx> wrote:
> > 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 heavy weight 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@xxxxxxx>
> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
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