From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathias Koehrer Subject: Re: Kernel thread's CPU affinity with isolcpus kernel boot argument Date: Fri, 26 Feb 2016 11:53:53 +0100 Message-ID: <56D02EC1.6000403@etas.com> References: <5698D4D0.3020907@etas.com> <20160225141806.GB16161@linutronix.de> <20160225144308.GG9598@jcartwri.amer.corp.natinst.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Cc: "linux-rt-users@vger.kernel.org" To: Josh Cartwright , Sebastian Andrzej Siewior Return-path: Received: from smtp6-v.fe.bosch.de ([139.15.237.11]:30444 "EHLO smtp6-v.fe.bosch.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753916AbcBZKx4 (ORCPT ); Fri, 26 Feb 2016 05:53:56 -0500 In-Reply-To: <20160225144308.GG9598@jcartwri.amer.corp.natinst.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: Am 25.02.2016 um 15:43 schrieb Josh Cartwright: > On Thu, Feb 25, 2016 at 03:18:06PM +0100, Sebastian Andrzej Siewior wrote: >> * Mathias Koehrer | 2016-01-15 12:15:28 [+0100]: >> >>> However, I noticed that most kernel threads use the affinity mask 0xff. >>> I can change this by using ???taskset???. However, I am wondering if >>> there is mechanism that forces the kernel to consider the value of >>> ???isolcpus??? also for kernel threads. >> >> not that I am aware of. There are a few per-CPU threads which have to >> stay the way they are. I would have expected that others like kworker/u* >> respect the isol CPUs and stay away. > > I suppose the higher level question to Mathias is: are you seeing these > threads perturb your application? Or, are you just observing they are > affinitized to isolcpus? We use isolcpus=1-31 to reserve all cores but core 0 for real time stuff. I just noticed, that some kernel threads have an affinity to cores > 0. So far I did not observe any disturbance from these threads. Thanks Mathias