From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754940AbeDCIFH (ORCPT ); Tue, 3 Apr 2018 04:05:07 -0400 Received: from mx2.suse.de ([195.135.220.15]:55864 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752581AbeDCIFG (ORCPT ); Tue, 3 Apr 2018 04:05:06 -0400 Date: Tue, 3 Apr 2018 10:05:03 +0200 From: Michal Hocko To: Li RongQing Cc: hannes@cmpxchg.org, vdavydov.dev@gmail.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: avoid the unnecessary waiting when force empty a cgroup Message-ID: <20180403080503.GE5501@dhcp22.suse.cz> References: <1522739529-5602-1-git-send-email-lirongqing@baidu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1522739529-5602-1-git-send-email-lirongqing@baidu.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 03-04-18 15:12:09, Li RongQing wrote: > The number of writeback and dirty page can be read out from memcg, > the unnecessary waiting can be avoided by these counts This changelog doesn't explain the problem and how the patch fixes it. Why do wee another throttling when we do already throttle in the reclaim path? > Signed-off-by: Li RongQing > --- > mm/memcontrol.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 9ec024b862ac..5258651bd4ec 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2613,9 +2613,13 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg) > progress = try_to_free_mem_cgroup_pages(memcg, 1, > GFP_KERNEL, true); > if (!progress) { > + unsigned long num; > + > + num = memcg_page_state(memcg, NR_WRITEBACK) + > + memcg_page_state(memcg, NR_FILE_DIRTY); > nr_retries--; > - /* maybe some writeback is necessary */ > - congestion_wait(BLK_RW_ASYNC, HZ/10); > + if (num) > + congestion_wait(BLK_RW_ASYNC, HZ/10); > } > > } > -- > 2.11.0 -- Michal Hocko SUSE Labs