From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id AB70A6B007E for ; Thu, 21 Jul 2011 07:36:39 -0400 (EDT) Date: Thu, 21 Jul 2011 13:36:26 +0200 From: Michal Hocko Subject: Re: [PATCH 2/4] memcg: unify sync and async per-cpu charge cache draining Message-ID: <20110721113626.GB27855@tiehlicka.suse.cz> References: <16dca2225fc14783a16d00c43f6680b67418da65.1311241300.git.mhocko@suse.cz> <20110721192525.56721c52.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110721192525.56721c52.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: linux-mm@kvack.org, Balbir Singh , Daisuke Nishimura , linux-kernel@vger.kernel.org On Thu 21-07-11 19:25:25, KAMEZAWA Hiroyuki wrote: > On Thu, 21 Jul 2011 09:50:00 +0200 > Michal Hocko 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 > > hmm..maybe good. > Reviewed-by: KAMEZAWA Hiroyuki Thanks -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org