From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53C80C83007 for ; Wed, 29 Apr 2020 07:51:44 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1437F20787 for ; Wed, 29 Apr 2020 07:51:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1437F20787 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BC2328E0006; Wed, 29 Apr 2020 03:51:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B715A8E0001; Wed, 29 Apr 2020 03:51:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A12A18E0006; Wed, 29 Apr 2020 03:51:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0041.hostedemail.com [216.40.44.41]) by kanga.kvack.org (Postfix) with ESMTP id 865B08E0001 for ; Wed, 29 Apr 2020 03:51:43 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 4E48C181AC550 for ; Wed, 29 Apr 2020 07:51:43 +0000 (UTC) X-FDA: 76760123286.02.cakes61_66498b16c0430 X-HE-Tag: cakes61_66498b16c0430 X-Filterd-Recvd-Size: 3320 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Wed, 29 Apr 2020 07:51:42 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 486F0ABD7; Wed, 29 Apr 2020 07:51:40 +0000 (UTC) Subject: Re: [patch] mm, oom: stop reclaiming if GFP_ATOMIC will start failing soon To: David Rientjes , Tetsuo Handa Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman References: <20200425172706.26b5011293e8dc77b1dccaf3@linux-foundation.org> <20200427133051.b71f961c1bc53a8e72c4f003@linux-foundation.org> <28e35a8b-400e-9320-5a97-accfccf4b9a8@suse.cz> From: Vlastimil Babka Message-ID: <31f1f84d-c5fe-824b-3c28-1a9ad69fcae5@suse.cz> Date: Wed, 29 Apr 2020 09:51:39 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 4/28/20 11:48 PM, David Rientjes wrote: > On Tue, 28 Apr 2020, Vlastimil Babka wrote: > > Yes, order-0 reclaim capture is interesting since the issue being reported > here is userspace going out to lunch because it loops for an unbounded > amount of time trying to get above a watermark where it's allowed to > allocate and other consumers are depleting that resource. > > We actually prefer to oom kill earlier rather than being put in a > perpetual state of aggressive reclaim that affects all allocators and the > unbounded nature of those allocations leads to very poor results for > everybody. Sure. My vague impression is that your (and similar cloud companies) kind of workloads are designed to maximize machine utilization, and overshooting and killing something as a result is no big deal. Then you perhaps have more probability of hitting this state, and on the other hand, even an occasional premature oom kill is not a big deal? My concers are workloads not designed in such a way, where premature oom kill due to temporary higher reclaim activity together with burst of incoming network packets will result in e.g. killing an important database. There, the tradeoff looks different. > I'm happy to scope this solely to an order-0 reclaim capture. I'm not > sure if I'm clear on whether this has been worked on before and patches > existed in the past? Andrew mentioned some. I don't recall any, so it might have been before my time. > Somewhat related to what I described in the changelog: we lost the "page > allocation stalls" artifacts in the kernel log for 4.15. The commit > description references an asynchronous mechanism for getting this > information; I don't know where this mechanism currently lives. >