Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753895Ab3ILO7M (ORCPT ); Thu, 12 Sep 2013 10:59:12 -0400 Received: from a14-74.smtp-out.amazonses.com ([54.240.14.74]:53285 "EHLO a14-74.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751631Ab3ILO7L (ORCPT ); Thu, 12 Sep 2013 10:59:11 -0400 X-Greylist: delayed 374 seconds by postgrey-1.27 at vger.kernel.org; Thu, 12 Sep 2013 10:59:11 EDT Date: Thu, 12 Sep 2013 14:52:56 +0000 From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Frederic Weisbecker cc: Andrew Morton , Gilad Ben-Yossef , Thomas Gleixner , Mike Frysinger , linux-kernel@vger.kernel.org, "Paul E. McKenney" Subject: Re: [RFC] Restrict kernel spawning of threads to a specified set of cpus. In-Reply-To: <20130912143137.GA23839@somewhere> Message-ID: <0000014112a921ae-51d171bf-e8d4-4569-bd20-94dabda2d5ba-000000@email.amazonses.com> References: <00000140efbcb701-c26320b3-f434-4538-bc80-8e92fed6f303-000000@email.amazonses.com> <20130911220228.GB15367@somewhere> <000001411282afa6-fe9c0543-0447-492b-991e-dc8214884b88-000000@email.amazonses.com> <20130912141625.GA23357@somewhere> <00000141128d759a-44dcacb6-8f48-4f9b-8381-d14003bd6da1-000000@email.amazonses.com> <20130912143137.GA23839@somewhere> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-SES-Outgoing: 2013.09.12-54.240.14.74 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 989 Lines: 26 On Thu, 12 Sep 2013, Frederic Weisbecker wrote: > > > Ok but you can change the affinity of a kthread from userspace, as > > > long as you define a cpu set that is among that kthread's cpus allowed. > > > > Ok but at that point kthread has already spawned a lot of kernel threads. > > > > The same is true for init and kmod. > > > > Ok but then we just need to set the affinity of all these kthreads. > A simple lookup on /proc/[0-9]+/ should do the trick. Yea but the kernel option makes it easy. No extras needed. Kernel brings it up user space cleanly configured and ready to go. This also allows us to cleanup kernel uses of cpumasks in such a way that proper thread placement for various other uses (reclaim f.e. kswpad) is possible. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/