From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932410AbdJ3PsJ (ORCPT ); Mon, 30 Oct 2017 11:48:09 -0400 Received: from resqmta-ch2-06v.sys.comcast.net ([69.252.207.38]:58872 "EHLO resqmta-ch2-06v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932322AbdJ3PsH (ORCPT ); Mon, 30 Oct 2017 11:48:07 -0400 Date: Mon, 30 Oct 2017 10:48:04 -0500 (CDT) From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Peter Zijlstra cc: cmetcalf@mellanox.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, torvalds@linux-foundation.org, hpa@zytor.com, riel@redhat.com, mingo@kernel.org, efault@gmx.de, frederic@kernel.org, kernellwp@gmail.com, paulmck@linux.vnet.ibm.com, lcapitulino@redhat.com, linux-tip-commits@vger.kernel.org Subject: Re: [tip:sched/core] sched/isolation: Document the isolcpus= flags In-Reply-To: <20171027135831.GZ3165@worktop.lehotels.local> Message-ID: References: <1509072159-31808-13-git-send-email-frederic@kernel.org> <20171027135831.GZ3165@worktop.lehotels.local> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-CMAE-Envelope: MS4wfHX9ka/gZmygnhNYfRlGW/Iwd1F+rdsFQQgpT0NuGZWs9cw0AktknP4AV4TTlmj1o/ftZDfUL/Vd44a49gfEN+MS5dowgeZ7uCNjBX+8QV17NtyalcnF x4gTfO6+ygUStw04JVNG5FIZy9FefJvFq6wGMmvDlK1nvrArLJY2Py31+Z6ZKE2L9Eg/Z+0VxBL7LU0AmkS4WeQihqJUUgJzI5T2o9Ppa2QIucFm6f4XcWy/ fq7wh5rdk4qIxHUnBUyA5buMgPYTpVueyy1Uq6V/a0JcAH/QGSIuNAgzbbLyNB4Yke4Mo2PD98u45KOBi59fTdsxZFh7moo0IM2BBoJbpEDJnnNkHg7d3H5V 5Hy7pmnK7/8KI0pcAw9c3H4lZvgz409jmY0juHGQgiC+ag1ml7WnHFyxJLhWTTVyVdpCGp9ZqqxYI4L2vYEMF3jyOEHIuzFparrrPJS3h71bKMFg4hB8IAW6 PYUjMKfivq2Nt6iKAU6xTYQ4tDGHyaYDzrZGEDkIqVdb2w6FvI5EoK+3gwNhc1HtBvP1uMcBzFhe7d4N2b2cijBnaMrb9J50UnJc7ksOrzsip6ggvjjk2UhS vSY= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 27 Oct 2017, Peter Zijlstra wrote: > I _strongly_ object to this statement, isolcpus is _not_ the preferred > way, cpusets are. > > And yes, while cpusets suffers some problems, we _should_ really fix > those and not promote this piece of shit isolcpus crap. Well low level control at the processor level is important and this allows controlling activities on a processor that is supposed to be dedicated to certain activities without OS interaction. isolcpus is the *right* approach here because you are micromanaging the OS and are putting dedicated pieces of software on each core. A cgroup suggests that threads would be scheduled over multiple cores which is *not* what you want. cgroup has to do something with containers etc which is inherently more noisy and needed if you want to do different things with your processing resources.