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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0BD64C54EAA for ; Fri, 27 Jan 2023 07:11:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 92AD88E0002; Fri, 27 Jan 2023 02:11:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8DAE88E0001; Fri, 27 Jan 2023 02:11:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7A2BC8E0002; Fri, 27 Jan 2023 02:11:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 6B1938E0001 for ; Fri, 27 Jan 2023 02:11:08 -0500 (EST) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 3DE8EAB262 for ; Fri, 27 Jan 2023 07:11:08 +0000 (UTC) X-FDA: 80399707416.05.646F0A4 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf02.hostedemail.com (Postfix) with ESMTP id 4E1EF80002 for ; Fri, 27 Jan 2023 07:11:06 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=nFLaAeUQ; spf=pass (imf02.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.28 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1674803466; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=6JbbjV8XPl8L1h6/eaMpCzQteeSN53ss/rnYjmgTrXA=; b=z6DRdiPFBNGEnDy+uW+8qcCwxRa3l0tQjKMas5B5Is7W75J31LISak0emGB4v50WuijllG T+IMWQ3snWbgoRWc4efox3FMyfztnP1GM+ol4I0v4/jAlew2EGXdBSFLbECcD+SnMgiHUK BKXo8eTU+RmCiDzHsdd8CdBJ4QvBhvY= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=nFLaAeUQ; spf=pass (imf02.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.28 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1674803466; a=rsa-sha256; cv=none; b=G+MiZRiLmUcn7n93qDwKjYTFTRbV7WvSKvkrkN36hMHwVPicm+gxXmi1kbg1RTal936t0O 7ClzxdFJoN87lP74JDxB5okCEz0+oTZDOCMaek8ad3AFGPFlmtNdKOl+kM+59OyY6EoIjQ vbq5xUYaO6Qs48bE3RBlpQN9ZE1q9rI= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id E330D21D76; Fri, 27 Jan 2023 07:11:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1674803464; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=6JbbjV8XPl8L1h6/eaMpCzQteeSN53ss/rnYjmgTrXA=; b=nFLaAeUQ5whgylpP8TWBYrurt2mzJIePEHISY2sElbE/wV9zCG0kZLTksxYkCGkDMJ7/e/ 3puaE1H2LxgFT2FnCyyJCM4ifWQt1a4LNfl8BvN/MsCuVlN/GJYyr42sQpyKXrL+diYIO4 uUAvQrDLDXGn7N/8wzS93CpH+RrBNFs= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id B78091336F; Fri, 27 Jan 2023 07:11:04 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id +x5rKgh502M7VgAAMHmgww (envelope-from ); Fri, 27 Jan 2023 07:11:04 +0000 Date: Fri, 27 Jan 2023 08:11:04 +0100 From: Michal Hocko To: Roman Gushchin Cc: Marcelo Tosatti , Leonardo =?iso-8859-1?Q?Br=E1s?= , Johannes Weiner , Shakeel Butt , Muchun Song , Andrew Morton , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Frederic Weisbecker Subject: Re: [PATCH v2 0/5] Introduce memcg_stock_pcp remote draining Message-ID: References: <20230125073502.743446-1-leobras@redhat.com> <9e61ab53e1419a144f774b95230b789244895424.camel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 4E1EF80002 X-Stat-Signature: ootw9nkmw6357ctg7xqrurygjo1jnnmo X-HE-Tag: 1674803466-981126 X-HE-Meta: U2FsdGVkX18SKR1OPmqxTRYt/VXkHimGWas4dnbFJbzdU5iINX5z86aVTFLfXqsCzcUBINMJCq/UvkiAi0FiPXL/2k0ouM2YtcY2fsmsEj1u1Q73vJC/wAdwns+o55p3GqNIhUIOECTzbf0F3lm84HA8NQAHAHhBxdoq38NrMsy6nBPTNmB5Wu02i0VRUd7ILFrrObic+V8xpDPcz8Gi5JtNSspVXWU5zqdfaAAPLZlvY8o2hUF2ykx464TbjbUV9B+alboax0theKnE0mme1xdP7z5yQj95btfwvNhJ7jJJBDo2mLCicCabROTp0jEMWhX8zg31DSrEIUHU4Pr4G4+j0q7OuPe6uwk2J3C/QBq+5WmRl4UU6+DdyCxJgndaLjPO8FJLozfQFd90RT1c8faD1Cv2xSyW9yIDHYKFkUgqzxK5Tt9Te4qfYxeTHVFoL8ZNCn46hSVLIDD+GgOdtpH9rTRd2fDTlxa1FqHZ2fZMKmxEK6BKgUYLo1KXSXav5y3/6ZGPpwbAQUheMZNE7CNIYgXJ9rOzjvG5auIhU1bHydlxzL5fEqb/Cx8YpMqEUVXsFd+fNI63cLvuW1NZSIGhqjZZlKNP0k9jF7zy9wOnkdw3FutbLmWY90TUI/8xq6i66i4MVcQ7jpUS01zW3mIrK1JOj0P7MnqindWQrT1p1wszYJnQVJECAt4m+o6Is7C9o9E12zjNiwShzTf8pGVR4wEgo/eoJG1C/YRLyS2GL4bTH8SfLt9dsqwe7Em3CqJdHsEmobP8Z+K//XZQOPhbD+x6tSgO2pgNFBmnnHOs+GScsQyeVvmW/xX5VMdZmU3ka4clcKJw0qRUc7skOtuiYTxJAUbR2IUiv7mKJsn3lemEWFcXWCs9Ye7HN66dlY9tCPJOi7GnICi8zVjljqOC2EIenHlI9in1nAmaECzKcPe+scEoNMBhrjtIRRIBoeookTuyCzVhEFAFTFa YvJc3TMV xBEKgviQgakCwI2dL+OKp68ULJTNiKbeZKcMfIImK9zjlemjCuBCqd/hu2uAe2bou/66xwZJxDBnYajwmuin2BUkKIUarGFaGBq4R4vHSkfr46AFNL7/D9u5tXJ7gSrYuXJzQvB4K8VglEcLQAK5hO33YE3euvYdeg/aMrziV5qY3HlOMwkeas6TlGL9sG7oF223vPp5Ovjk64KWG1Dj9+cfaPMsSbmsR1Xutl30j96aNbwPgjEQieRulr0c/MnYyH24r 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: [Cc Frederic] On Thu 26-01-23 15:12:35, Roman Gushchin wrote: > On Thu, Jan 26, 2023 at 08:41:34AM +0100, Michal Hocko wrote: [...] > > > Essentially each cpu will try to grab the remains of the memory quota > > > and move it locally. I wonder in such circumstances if we need to disable the pcp-caching > > > on per-cgroup basis. > > > > I think it would be more than sufficient to disable pcp charging on an > > isolated cpu. > > It might have significant performance consequences. Is it really significant? > I'd rather opt out of stock draining for isolated cpus: it might slightly reduce > the accuracy of memory limits and slightly increase the memory footprint (all > those dying memcgs...), but the impact will be limited. Actually it is limited > by the number of cpus. Hmm, OK, I have misunderstood your proposal. Yes, the overal pcp charges potentially left behind should be small and that shouldn't really be a concern for memcg oom situations (unless the limit is very small and workloads on isolated cpus using small hard limits is way beyond my imagination). My first thought was that those charges could be left behind without any upper bound but in reality sooner or later something should be running on those cpus and if the memcg is gone the pcp cache would get refilled and old charges gone. So yes, this is actually a better and even simpler solution. All we need is something like this diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ab457f0394ab..13b84bbd70ba 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2344,6 +2344,9 @@ static void drain_all_stock(struct mem_cgroup *root_memcg) struct mem_cgroup *memcg; bool flush = false; + if (cpu_is_isolated(cpu)) + continue; + rcu_read_lock(); memcg = stock->cached; if (memcg && stock->nr_pages && There is no such cpu_is_isolated() AFAICS so we would need a help from NOHZ and cpuisol people to create one for us. Frederic, would such an abstraction make any sense from your POV? -- Michal Hocko SUSE Labs