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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 D91F5C4151A for ; Tue, 29 Jan 2019 14:43:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A8F8221473 for ; Tue, 29 Jan 2019 14:43:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548772992; bh=1YHaNgJNYbqTBaPd3fpVlrbvWM1kC7HMYAo6DJJai4o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=UntP966cLArDGeqHmyOwGaj9hSA8ZZwwRSdAQiY5wqDBDEQYQOBj9314aICVp2fIZ 5nN5gb/DTOtD1rPygctk2BHlWhYltNGvsN59PMTJ9ky16p0WgoRsxPQW42L+ioGawX MHQkdbJspSw3FOcp0nYMZRSHKpKiLgCTD5Ue5TOw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727270AbfA2OnL (ORCPT ); Tue, 29 Jan 2019 09:43:11 -0500 Received: from mx2.suse.de ([195.135.220.15]:47060 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725730AbfA2OnJ (ORCPT ); Tue, 29 Jan 2019 09:43:09 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2BBAFB049; Tue, 29 Jan 2019 14:43:08 +0000 (UTC) Date: Tue, 29 Jan 2019 15:43:06 +0100 From: Michal Hocko To: Tejun Heo Cc: Johannes Weiner , Chris Down , Andrew Morton , Roman Gushchin , Dennis Zhou , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, kernel-team@fb.com Subject: Re: [PATCH 2/2] mm: Consider subtrees in memory.events Message-ID: <20190129144306.GO18811@dhcp22.suse.cz> References: <20190125173713.GD20411@dhcp22.suse.cz> <20190125182808.GL50184@devbig004.ftw2.facebook.com> <20190128125151.GI18811@dhcp22.suse.cz> <20190128142816.GM50184@devbig004.ftw2.facebook.com> <20190128145210.GM18811@dhcp22.suse.cz> <20190128145407.GP50184@devbig004.ftw2.facebook.com> <20190128151859.GO18811@dhcp22.suse.cz> <20190128154150.GQ50184@devbig004.ftw2.facebook.com> <20190128170526.GQ18811@dhcp22.suse.cz> <20190128174905.GU50184@devbig004.ftw2.facebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190128174905.GU50184@devbig004.ftw2.facebook.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 28-01-19 09:49:05, Tejun Heo wrote: > Hello, Michal. > > On Mon, Jan 28, 2019 at 06:05:26PM +0100, Michal Hocko wrote: > > Yeah, that is quite clear. But it also assumes that the hierarchy is > > pretty stable but cgroups might go away at any time. I am not saying > > that the aggregated events are not useful I am just saying that it is > > quite non-trivial to use and catch all potential corner cases. Maybe I > > It really isn't complicated and doesn't require stable subtree. > > > am overcomplicating it but one thing is quite clear to me. The existing > > semantic is really useful to watch for the reclaim behavior at the > > current level of the tree. You really do not have to care what is > > happening in the subtree when it is clear that the workload itself > > is underprovisioned etc. Considering that such a semantic already > > existis, somebody might depend on it and we likely want also aggregated > > semantic then I really do not see why to risk regressions rather than > > add a new memory.hierarchy_events and have both. > > The problem then is that most other things are hierarchical including > some fields in .events files, so if we try to add local stats and > events, there's no good way to add them. All memcg events are represented non-hierarchical AFAICS memcg_memory_event() simply accounts at the level when it happens. Or do I miss something? Or are you talking about .events files for other controllers? -- Michal Hocko SUSE Labs