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=-2.5 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 AB368C282C3 for ; Thu, 24 Jan 2019 16:00:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7837F217D7 for ; Thu, 24 Jan 2019 16:00:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="aOZLgnWF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728650AbfAXQAN (ORCPT ); Thu, 24 Jan 2019 11:00:13 -0500 Received: from mail-yw1-f66.google.com ([209.85.161.66]:35496 "EHLO mail-yw1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727848AbfAXQAM (ORCPT ); Thu, 24 Jan 2019 11:00:12 -0500 Received: by mail-yw1-f66.google.com with SMTP id h32so2619459ywk.2 for ; Thu, 24 Jan 2019 08:00:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=hCxh8cKbdjdveceYE2dpaNIbo3dOi85oEdfOpSI1M70=; b=aOZLgnWFCiEp/DgAqJ0ZNWqNTjzcc5vJt9MAo9H/VK+bDPLL728DCs/dQTYumayW9b hwEBKayaUcXB/Sm2wVblmZUXpmcYCgw5srU72fEnOiwv6GvjLFt7QQLCA15lf/iLKQTe I2LZ9iXuNZVAc9x6w0w1nXX6r3sUSWtCQcX4vldjXpJSKymA1bOwkAdtqaA3BVwhK1pi 6XP/Xvmi4a2Fkd60WeR1k85nxSzSrbRmyv8/HOAf2fs9EJyFHmoNqroNwCqPIdMxMz4e dNaWR2UqiCiGbVN1MaIK7kUOEqQUqWZbXjT6WX1XVcLMZ5aPHFeN5L19jQqp84gLGZ8p iglw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=hCxh8cKbdjdveceYE2dpaNIbo3dOi85oEdfOpSI1M70=; b=YcmoaulMETt6dSboOQxzWA0CdLRcfyISbm8O/XDZ5EC9/mssh/rqbo+jn5qWfP0+pA TnHip3yCeoYKjY/9ue3Iclt7c2qjkXvkbIovSeMWg2w2sFBYP9+uXdI6fybSzQmL9+Gv DJFLl89dRaEwAamgfevjGFl6ArF62xBc5xCSdTmxWKr/t1i1trIyf3z+484Cz+Kcwszm GJgbQC6c081hxW8XZ3A0o521f3pGK3acZl9SKUSaOevaFqnQD9rJBC9Fcfe/USaKEWvM 936wv99KgteDVx8wOv7xE7MhkRMX3wKGYlieYFMRZCL+WFszlMGMTA2Ad9nqkYR8HzSw twLQ== X-Gm-Message-State: AJcUukfvH4DdFtkJTCvqrR6KCdlwm+gIQ5NFqKr4RGnCPXqFXnfQTGuI /AYYKJTdPwxeEN1gner3edjVdA== X-Google-Smtp-Source: ALg8bN4aBCGv35jkyWZhnUPF09RZsGCyquxrn8LBm4z5TdGfoUswZlR81XbS9m6yHGE0HB/Lw6uFvw== X-Received: by 2002:a0d:df87:: with SMTP id i129mr6886876ywe.474.1548345611594; Thu, 24 Jan 2019 08:00:11 -0800 (PST) Received: from localhost ([2620:10d:c091:200::5:9b5d]) by smtp.gmail.com with ESMTPSA id w2sm13081675ywl.10.2019.01.24.08.00.10 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 24 Jan 2019 08:00:10 -0800 (PST) Date: Thu, 24 Jan 2019 11:00:10 -0500 From: Johannes Weiner To: Michal Hocko Cc: Chris Down , Andrew Morton , Tejun Heo , 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: <20190124160009.GA12436@cmpxchg.org> References: <20190123223144.GA10798@chrisdown.name> <20190124082252.GD4087@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190124082252.GD4087@dhcp22.suse.cz> User-Agent: Mutt/1.11.2 (2019-01-07) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 24, 2019 at 09:22:52AM +0100, Michal Hocko wrote: > On Wed 23-01-19 17:31:44, Chris Down wrote: > > Acked-by: Johannes Weiner > > btw. I do not see this patch posted anywhere yet it already comes with > an ack. Have I just missed a previous version? I reviewed it offline before Chris sent it out. I agree with the sentiment that the non-hierarchical behavior was an oversight, not a design decision. The arguments against the change don't convince me: the added difficulty of finding out local values is true for all other cgroup files as well. This is traded off with being able to detect any subtree state from the first level cgroups and drill down on-demand, without having to scan the entire tree on each monitoring interval. That's a trade-off we've made everywhere else, so this is simply an inconsistency, not a legitimate exception to the rule. We cannot fully eliminate a risk for regression, but it strikes me as highly unlikely, given the extremely young age of cgroup2-based system management and surrounding tooling. Acked-by: Johannes Weiner