From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751917AbeCNT5R (ORCPT ); Wed, 14 Mar 2018 15:57:17 -0400 Received: from mail-yw0-f194.google.com ([209.85.161.194]:35294 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751860AbeCNT5O (ORCPT ); Wed, 14 Mar 2018 15:57:14 -0400 X-Google-Smtp-Source: AG47ELtCDk44Znq8mlh5Ao860KVd9hEqIvnNKXMwazQbX0l2wkgWiO+pGoLMNd1GPASBJ1y5oYdkbg== Date: Wed, 14 Mar 2018 12:57:11 -0700 From: Tejun Heo To: Mike Galbraith Cc: Waiman Long , Peter Zijlstra , Li Zefan , Johannes Weiner , Ingo Molnar , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, torvalds@linux-foundation.org, Roman Gushchin Subject: Re: [PATCH v4] cpuset: Enable cpuset controller in default hierarchy Message-ID: <20180314195711.GD2943022@devbig577.frc2.facebook.com> References: <1520609707-16582-1-git-send-email-longman@redhat.com> <1520613285.12489.36.camel@gmx.de> <1c3fe7b0-2600-c46d-1527-d3aaf024bb91@redhat.com> <1520619426.27998.18.camel@gmx.de> <55809fe4-98ba-5566-86ed-457acfef0e1c@redhat.com> <1520624424.27998.76.camel@gmx.de> <53de9683-01b7-bac4-8b70-dc1f93ede600@redhat.com> <20180309221736.GB5926@hirez.programming.kicks-ass.net> <1520653648.12749.20.camel@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1520653648.12749.20.camel@gmx.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Sat, Mar 10, 2018 at 04:47:28AM +0100, Mike Galbraith wrote: > Some form of cpu_exclusive (preferably exactly that, but something else > could replace it) is needed to define sets that must not overlap any > other set at creation time or any time thereafter.  A set with property > 'exclusive' is the enabler for fundamentally exclusive (but dynamic!) > set properties such as 'isolated' (etc etc). I'm not sure cpu_exclusive makes sense. A controller knob can either belong to the parent or the cgroup itself and cpu_exclusive doesn't make sense in either case. 1. cpu_exclusive is owned by the parent as other usual resource control knobs. IOW, it's not delegatable. This is weird because it's asking the kernel to protect against its own misconfiguration and there's nothing preventing cpu_exclusive itself being cleared by the same entitya. 2. cpu_exclusive is owned by the cgroup itself like memory.oom_group. IOW, it's delegatable. This allows a cgroup to affect what its siblings can or cannot do, which is broken. Semantically, it doesn't make much sense either. I don't think it's a good idea to add a kernel mechanism to prevent misconfiguration from a single entity. Thanks. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-4.9 required=5.0 tests=DKIM_SIGNED,RCVD_IN_DNSWL_HI, T_DKIM_INVALID,T_RP_MATCHES_RCVD autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id AD54C7E6AB for ; Wed, 14 Mar 2018 19:57:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751869AbeCNT5Q (ORCPT ); Wed, 14 Mar 2018 15:57:16 -0400 Received: from mail-yw0-f194.google.com ([209.85.161.194]:35294 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751860AbeCNT5O (ORCPT ); Wed, 14 Mar 2018 15:57:14 -0400 Received: by mail-yw0-f194.google.com with SMTP id c20so3026683ywa.2; Wed, 14 Mar 2018 12:57:14 -0700 (PDT) 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:content-transfer-encoding:in-reply-to :user-agent; bh=mNzR5KMENUVyWqgjSK1EivG7Spr6h4RxAlgh2Yc24WM=; b=XTvqYQXK1C1k9E21UsRSJOZN/kIIyps4bpjY0Qon060BgZjLa97m9DhwCdsw6xpKaL v6kTgRV0HG1aGOUvExuxD89UmM8piax+7xnkbxX1mkxRAyQmAWsDhoixas0TAz3oPjsD APqP4YEDdUXG+lyOULY18qKn+/cN3AZWIt9mKem3HgQxHcNdV03fPVVl32sL1uJZejkE 1bKwJU4wWxOaG2pO1vM1/S9a2nUUdsHjKnofq+lpBvPg7KtRVIC8aPvmV9tqrwSX3EAm fImguSpAIVjBIWVvKdg0s4JdxAQ6eVcZBDycC9PwMRb5fpKrqAh0QUWQnEssc5RaDEze UYwg== 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 :content-transfer-encoding:in-reply-to:user-agent; bh=mNzR5KMENUVyWqgjSK1EivG7Spr6h4RxAlgh2Yc24WM=; b=qKfloew/HNMRq6yzC3DNcxe4DVQMR3MGHapd0Phv1OeKQrgTv7CMh1CZ6kh5/dnQC6 bQKvNDQat5u5d7i8fu/HBbPmXVwSYsAZ0EI8OFBGhiJOwDYRT3WVwtU47mQxYKXm5KSg 582yUAUMXVA+UtcGDltoTPg/m9WFmLKXLQNChnHnhFrkFhC7JJ1/9tpHNaqyIapIUy5D 6h8WeJzmqP12eUaMJIMn/CalbPWqZ9pp82u/Gkjd5xSuig9/EcGgRFRuv562BZ1eKOfL Mcai97Rg+9T4gQCES1Q4H7KDQj1NB6VKr4q6jaTbJfMy58BSn+9y/vIoLf4Basbl9+Ip vrBA== X-Gm-Message-State: AElRT7Fh3YoOK+GO0bsCOO/Aqn/MRR1da/K8HfW268zj3JxVoURMzWuk rpCunJWW/ZrAe5PpJUn55PI= X-Google-Smtp-Source: AG47ELtCDk44Znq8mlh5Ao860KVd9hEqIvnNKXMwazQbX0l2wkgWiO+pGoLMNd1GPASBJ1y5oYdkbg== X-Received: by 10.129.216.9 with SMTP id d9mr4133623ywj.283.1521057433753; Wed, 14 Mar 2018 12:57:13 -0700 (PDT) Received: from localhost ([2620:10d:c091:200::6ef7]) by smtp.gmail.com with ESMTPSA id l145sm1296125ywb.105.2018.03.14.12.57.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 14 Mar 2018 12:57:12 -0700 (PDT) Date: Wed, 14 Mar 2018 12:57:11 -0700 From: Tejun Heo To: Mike Galbraith Cc: Waiman Long , Peter Zijlstra , Li Zefan , Johannes Weiner , Ingo Molnar , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, torvalds@linux-foundation.org, Roman Gushchin Subject: Re: [PATCH v4] cpuset: Enable cpuset controller in default hierarchy Message-ID: <20180314195711.GD2943022@devbig577.frc2.facebook.com> References: <1520609707-16582-1-git-send-email-longman@redhat.com> <1520613285.12489.36.camel@gmx.de> <1c3fe7b0-2600-c46d-1527-d3aaf024bb91@redhat.com> <1520619426.27998.18.camel@gmx.de> <55809fe4-98ba-5566-86ed-457acfef0e1c@redhat.com> <1520624424.27998.76.camel@gmx.de> <53de9683-01b7-bac4-8b70-dc1f93ede600@redhat.com> <20180309221736.GB5926@hirez.programming.kicks-ass.net> <1520653648.12749.20.camel@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1520653648.12749.20.camel@gmx.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Hello, On Sat, Mar 10, 2018 at 04:47:28AM +0100, Mike Galbraith wrote: > Some form of cpu_exclusive (preferably exactly that, but something else > could replace it) is needed to define sets that must not overlap any > other set at creation time or any time thereafter.  A set with property > 'exclusive' is the enabler for fundamentally exclusive (but dynamic!) > set properties such as 'isolated' (etc etc). I'm not sure cpu_exclusive makes sense. A controller knob can either belong to the parent or the cgroup itself and cpu_exclusive doesn't make sense in either case. 1. cpu_exclusive is owned by the parent as other usual resource control knobs. IOW, it's not delegatable. This is weird because it's asking the kernel to protect against its own misconfiguration and there's nothing preventing cpu_exclusive itself being cleared by the same entitya. 2. cpu_exclusive is owned by the cgroup itself like memory.oom_group. IOW, it's delegatable. This allows a cgroup to affect what its siblings can or cannot do, which is broken. Semantically, it doesn't make much sense either. I don't think it's a good idea to add a kernel mechanism to prevent misconfiguration from a single entity. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html