Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423187Ab2KNSdx (ORCPT ); Wed, 14 Nov 2012 13:33:53 -0500 Received: from zene.cmpxchg.org ([85.214.230.12]:34283 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423150Ab2KNSdv (ORCPT ); Wed, 14 Nov 2012 13:33:51 -0500 Date: Wed, 14 Nov 2012 13:33:30 -0500 From: Johannes Weiner To: Michal Hocko Cc: Andrew Morton , Glauber Costa , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo , Li Zefan , KAMEZAWA Hiroyuki , Balbir Singh Subject: Re: [PATCH v3 3/6] memcg: Simplify mem_cgroup_force_empty_list error handling Message-ID: <20121114183330.GA32421@cmpxchg.org> References: <1351251453-6140-1-git-send-email-mhocko@suse.cz> <1351251453-6140-4-git-send-email-mhocko@suse.cz> <508E8B95.406@parallels.com> <20121029150022.a595b866.akpm@linux-foundation.org> <20121030103559.GA7394@dhcp22.suse.cz> <20121113211041.GB1543@cmpxchg.org> <20121114135930.GE4929@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121114135930.GE4929@dhcp22.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1111 Lines: 22 On Wed, Nov 14, 2012 at 02:59:30PM +0100, Michal Hocko wrote: > On Tue 13-11-12 16:10:41, Johannes Weiner wrote: > > Would it make sense to stick a wait_on_page_locked() in there just so > > that we don't busy spin on a page under migration/reclaim? > > Hmm, this would also mean that get_page_unless_zero would fail as well > and so we would schedule in mem_cgroup_force_empty_list. It is true that > there might be no other runnable task so we can busy loop so yes this > would help. Care to cook the patch? Eventually get_page_unless_zero() would fail but we could still spin on a page while it's off the LRU and migration performs writeback on it e.g. cond_resched() does not necessarily schedule just because there is another runnable task, I think, it's voluntary preemption when the task needs rescheduling anyway, not yield. Maybe not worth bothering... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/