From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f174.google.com (mail-wi0-f174.google.com [209.85.212.174]) by kanga.kvack.org (Postfix) with ESMTP id 8F1C26B0038 for ; Tue, 27 Oct 2015 08:07:07 -0400 (EDT) Received: by wicll6 with SMTP id ll6so156345159wic.0 for ; Tue, 27 Oct 2015 05:07:07 -0700 (PDT) Received: from mail-wi0-f181.google.com (mail-wi0-f181.google.com. [209.85.212.181]) by mx.google.com with ESMTPS id m19si13596443wjr.103.2015.10.27.05.07.06 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Oct 2015 05:07:06 -0700 (PDT) Received: by wicll6 with SMTP id ll6so156982443wic.1 for ; Tue, 27 Oct 2015 05:07:05 -0700 (PDT) Date: Tue, 27 Oct 2015 13:07:04 +0100 From: Michal Hocko Subject: Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable() checks Message-ID: <20151027120704.GF9891@dhcp22.suse.cz> References: <20151023083316.GB2410@dhcp22.suse.cz> <20151023103630.GA4170@mtj.duckdns.org> <20151023111145.GH2410@dhcp22.suse.cz> <201510232125.DAG82381.LMJtOQFOHVOSFF@I-love.SAKURA.ne.jp> <20151023182343.GB14610@mtj.duckdns.org> <201510251952.CEF04109.OSOtLFHFVFJMQO@I-love.SAKURA.ne.jp> <20151027092231.GC9891@dhcp22.suse.cz> <20151027105506.GB18741@mtj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151027105506.GB18741@mtj.duckdns.org> Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Tetsuo Handa , cl@linux.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, rientjes@google.com, oleg@redhat.com, kwalker@redhat.com, akpm@linux-foundation.org, hannes@cmpxchg.org, vdavydov@parallels.com, skozina@redhat.com, mgorman@suse.de, riel@redhat.com On Tue 27-10-15 19:55:06, Tejun Heo wrote: > On Tue, Oct 27, 2015 at 10:22:31AM +0100, Michal Hocko wrote: > ... > > stable kernels without causing any other regressions. 2) is the way > > to move forward for next kernels and we should really think whether > > WQ_MEM_RECLAIM should imply also WQ_HIGHPRI by default. If there is a > > general consensus that there are legitimate WQ_MEM_RECLAIM users which > > can do without the other flag then I am perfectly OK to use it for > > vmstat and oom sysrq dedicated workqueues. > > I don't think flagging these things is a good approach. These are too > easy to miss. If this is a problem which needs to be solved, which > I'm not convined it is at this point, the right thing to do would be > doing stall detection and kicking the next work item automatically. To be honest, I do not really care whether this gets "fixed" in the stall detection code or by making WQ_MEM_RECLAIM to flag a special behavior implicitly. All I would like to see is to have a guarantee that such workqueues are not staying behind just because all current workers are in the allocator. Adding artificial schedule_timeouts in the allocator is a fragile way to work around the issue. -- Michal Hocko SUSE Labs -- 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/ . Don't email: email@kvack.org