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=-3.7 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 BD7EBC282C6 for ; Fri, 25 Jan 2019 18:28:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 95273218CD for ; Fri, 25 Jan 2019 18:28:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548440894; bh=aIpeptfYyL0l5PwRvDcbK6pFmvDhX6ouucxrUpc27xo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=f8UQg43NncMK/289406O5qWambFOwyVZjcRrB00SVA8yIzhfcaW0ULcg6uLX9gYYq PXvvoSjQ4cymDOSCQw7Ghrl/sHMQiuo1AW+IW1tz9JqlSxNCSuhLXSvEvM8U0VeLj1 rBn7TfMGOcLVgp1t3pMh7MG1sQerEnPqZfSxB3fM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729368AbfAYS2N (ORCPT ); Fri, 25 Jan 2019 13:28:13 -0500 Received: from mail-yb1-f195.google.com ([209.85.219.195]:41252 "EHLO mail-yb1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726321AbfAYS2M (ORCPT ); Fri, 25 Jan 2019 13:28:12 -0500 Received: by mail-yb1-f195.google.com with SMTP id y63so4197403ybc.8; Fri, 25 Jan 2019 10:28:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=KND47oB4UJZskQI8jxAjNs+9fiy3pLDDFs2RkvN4z38=; b=qW7KobFB8kOYKRY9BwGWo1btTcXtc8skavDL1VI3l87kZnQXRZ2FnGLCBHB6ozDc73 iXXl37VMG4ga2hDrxuWSDaB/XwzZZhDmraOMkIOwQrb17Nlk7u2zJiHHt1gJuyz+bQTJ gflVtTUzwPKDsLFckc5Af8ISyjgXUvKcvwum2VaW/F9JLIO8MnykBSH81u9petfaDY2H HkqYcznDg5UwcRScWnxI85dkmPyD6KSuoW8vc+h4t8QTvVWQxgLQcgPNgSlv294kBysC z/7ksrB0IBpM9tPsUf3jMV/KQfKUAyW4I2GyW6MGBOA5Fu2JWFVjvuVjtuWCqlekulkb ojlA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=KND47oB4UJZskQI8jxAjNs+9fiy3pLDDFs2RkvN4z38=; b=lwHISUpI8P+p+pwOPCguuUSXJqMvSPYZrPRpkZPdMqMChVhCLU12mxljaloLGNpgzE Ztmj0T9aYYYOFfkdOQwIJUclI+2pFBvfy96oiwioaZdKLBTw20HMTFjASzqlrCey+i7I U8deb5FHFbOya7bu6rKMbnUMbrQqHU325qBie2qgauz9jMq+r5MDXjjycxf96pQOXdUp iCaaaGDJTCWJ8FbYwjDs0ZJip0iFh7lFxBVwnEPW85jl4yoKj7jpraHYRP9lyEav8n8I S7y66IyjfI9OYhLGn5YDeK2mz9NP1VBtObz0sXWc9JLPtPbg0PvC4b0YoI62XtMAw+Z3 mJZg== X-Gm-Message-State: AJcUukcEuzU5fdgTsgh9a6jKfTpgYMHId0Y/pN1fjYoQMuC6c68xftBe zGp/i3sDnEWAoFIBxWwxa70= X-Google-Smtp-Source: ALg8bN75xJCQpIK2wjwy+yhnkWY07DNhoXbmtzKJYc4axxcBDSXgnaOGeNa4ieWaRh+Y3vxKeCpadw== X-Received: by 2002:a25:3b82:: with SMTP id i124mr11619415yba.183.1548440891311; Fri, 25 Jan 2019 10:28:11 -0800 (PST) Received: from localhost ([2620:10d:c091:200::7:a62a]) by smtp.gmail.com with ESMTPSA id a15sm4645358ywh.64.2019.01.25.10.28.09 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 25 Jan 2019 10:28:09 -0800 (PST) Date: Fri, 25 Jan 2019 10:28:08 -0800 From: Tejun Heo To: Michal Hocko 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: <20190125182808.GL50184@devbig004.ftw2.facebook.com> References: <20190123223144.GA10798@chrisdown.name> <20190124082252.GD4087@dhcp22.suse.cz> <20190124160009.GA12436@cmpxchg.org> <20190124170117.GS4087@dhcp22.suse.cz> <20190124182328.GA10820@cmpxchg.org> <20190125074824.GD3560@dhcp22.suse.cz> <20190125165152.GK50184@devbig004.ftw2.facebook.com> <20190125173713.GD20411@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190125173713.GD20411@dhcp22.suse.cz> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Michal. On Fri, Jan 25, 2019 at 06:37:13PM +0100, Michal Hocko wrote: > > What if a user wants to monitor any ooms in the subtree tho, which is > > a valid use case? > > How is that information useful without know which memcg the oom applies > to? For example, a workload manager watching over a subtree for a job with nested memory limits set by the job itself. It wants to take action (reporting and possibly other remediative actions) when something goes wrong in the delegated subtree but isn't involved in how the subtree is configured inside. > > If local event monitoring is useful and it can be, > > let's add separate events which are clearly identifiable to be local. > > Right now, it's confusing like hell. > > From a backward compatible POV it should be a new interface added. That sure is an option for use cases like above but it has the downside of carrying over the confusing interface into the indefinite future. Again, I'd like to point back at how we changed the accounting write and trim accounting because the benefits outweighted the risks. > Please note that I understand that this might be confusing with the rest > of the cgroup APIs but considering that this is the first time somebody > is actually complaining and the interface is "production ready" for more > than three years I am not really sure the situation is all that bad. cgroup2 uptake hasn't progressed that fast. None of the major distros or container frameworks are currently shipping with it although many are evaluating switching. I don't think I'm too mistaken in that we (FB) are at the bleeding edge in terms of adopting cgroup2 and its various new features and are hitting these corner cases and oversights in the process. If there are noticeable breakages arising from this change, we sure can backpaddle but I think the better course of action is fixing them up while we can. Thanks. -- tejun