lkml.org 
[lkml]   [2011]   [Jul]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/4] memcg: unify sync and async per-cpu charge cache draining
On Thu 21-07-11 19:25:25, KAMEZAWA Hiroyuki wrote:
> On Thu, 21 Jul 2011 09:50:00 +0200
> Michal Hocko <mhocko@suse.cz> wrote:
>
> > Currently we have two ways how to drain per-CPU caches for charges.
> > drain_all_stock_sync will synchronously drain all caches while
> > drain_all_stock_async will asynchronously drain only those that refer to
> > a given memory cgroup or its subtree in hierarchy.
> > Targeted async draining has been introduced by 26fe6168 (memcg: fix
> > percpu cached charge draining frequency) to reduce the cpu workers
> > number.
> >
> > sync draining is currently triggered only from mem_cgroup_force_empty
> > which is triggered only by userspace (mem_cgroup_force_empty_write) or
> > when a cgroup is removed (mem_cgroup_pre_destroy). Although these are
> > not usually frequent operations it still makes some sense to do targeted
> > draining as well, especially if the box has many CPUs.
> >
> > This patch unifies both methods to use the single code (drain_all_stock)
> > which relies on the original async implementation and just adds
> > flush_work to wait on all caches that are still under work for the sync
> > mode.
> > We are using FLUSHING_CACHED_CHARGE bit check to prevent from waiting on
> > a work that we haven't triggered.
> > Please note that both sync and async functions are currently protected
> > by percpu_charge_mutex so we cannot race with other drainers.
> >
> > Signed-off-by: Michal Hocko <mhocko@suse.cz>
>
> hmm..maybe good.
> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Thanks

--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic


\
 
 \ /
  Last update: 2011-07-21 13:39    [W:0.036 / U:0.444 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site