From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932513AbdJ3Q6K convert rfc822-to-8bit (ORCPT ); Mon, 30 Oct 2017 12:58:10 -0400 Received: from mout.gmx.net ([212.227.15.19]:53117 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932361AbdJ3Q6H (ORCPT ); Mon, 30 Oct 2017 12:58:07 -0400 Message-ID: <1509382585.7399.17.camel@gmx.de> Subject: Re: [tip:sched/core] sched/isolation: Document the isolcpus= flags From: Mike Galbraith To: Peter Zijlstra , Christopher Lameter 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, frederic@kernel.org, kernellwp@gmail.com, paulmck@linux.vnet.ibm.com, lcapitulino@redhat.com, linux-tip-commits@vger.kernel.org Date: Mon, 30 Oct 2017 17:56:25 +0100 In-Reply-To: <20171030161101.wprohopz5eg7snb4@hirez.programming.kicks-ass.net> References: <1509072159-31808-13-git-send-email-frederic@kernel.org> <20171027135831.GZ3165@worktop.lehotels.local> <20171030161101.wprohopz5eg7snb4@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.20.5 Mime-Version: 1.0 Content-Transfer-Encoding: 8BIT X-Provags-ID: V03:K0:GrQkmmKngu8+06PxcNS9FPExbFDcNLq/w6V7gzIVblElVXZHS5z Uu49dIJhy4bOHcy5xL/fdUKBzh2rtpjckJFb4PbcsC8xBqAk7c2PjebmlwpFDA/Z8He9CMI TbZp6Ch6qxBwI7gJ/A2AUD4wVmx6YHvImLOC+6OCHrq6QEyIiVn5o2NnFm/qhEtJab231G7 hDAm73/miHe6pSWLJEXjg== X-UI-Out-Filterresults: notjunk:1;V01:K0:gGn8fsxzjx4=:NcFyvanrucQH+K1ESqTtdZ qxAj/1c+xHnGGujk4/At2OjdavghuSCPmlpf0U+d7N87vyO2aVw3x8+N+Wpegekw2mNG/Msh8 tuAtOx2OdQh8NK6m8dRaFmM93hzPa2Adj9MGGrgyEAtvhccv0Vu7sq33JOadIuwgWLfH0grPJ /hZI6LQFjpLf/pHCWWoeMclKmva0qMVsRAYp/dvNVdBDB0sot7K9gcgs+z4f8bqvAIVK0P7bW gTAt2IZzIz1msm3PPZ0yHDHFhXKLqfrsFhWC0ZaJccxMy1EhGJgFebcfYuuzu1In+U/lB95g+ 1ZA+Lg3lIrAXCqvpyvC6CkdtZmeBJUo3yym0zlZEJOM+TSXSMABvo6DhBp1v7OYJrZdM+owZ6 HCGNIK/DHowKJumhOxQ1g1Nx1tTRUsAgtCBN9RmTY34W6OuQlrlMubYGP7iIrr/7zLM/GPW+6 Mj60bwypNWgt9ADhRiXBbb/iJGh44u8Fa5mdqEUrsxT3kafKRYPCPNxZaqvpNaAhBhNePQ9SI RzJAPOwBpx2ej8RyklISEOfCHgA99FEatz8RA9HC3oZxmtQDFCAquMrNs9f6b3Uqd04h1Ir+X ffxwlKxQXcMGlYkAZfDfv5gPvd87bAVFjvlfmf/zGA3c2tcZYRKGiJEemmyQi9n4VERbvQfpM lH6vf/OZngYhBjkFkoJGjgGXiFJv1R3Nx1NNv1nqfytkJojp5gYvBB/5/yoSXAdzEKIv1UMH8 5P0HJhJgOwKU9GzWyVscwVfUSiZ2KRKr8r+t+VWtHN88GziVLcwvJhjJKytJRAfy5uVHohvm/ Dq7SqiPlPBG0kbosbvK71rHnLwwcqRzZ1zeHdYpGuRu33Jw46Y= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2017-10-30 at 17:11 +0100, Peter Zijlstra wrote: > On Mon, Oct 30, 2017 at 10:48:04AM -0500, Christopher Lameter wrote: > > 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. > > That is what you want, and cpusets should allow for that just fine. > > > A cgroup suggests that threads would be scheduled over multiple cores > > which is *not* what you want. > > No, that suggestion is false. cpusets should allow you to isolate > individual CPUs just fine. It does.  I do RT jitter testing with it regularly.  If it didn't work, my 8 socket box would let me know instantly, by completely sucking :) -Mike