Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757459Ab3IMPoy (ORCPT ); Fri, 13 Sep 2013 11:44:54 -0400 Received: from a9-66.smtp-out.amazonses.com ([54.240.9.66]:51001 "EHLO a9-66.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755753Ab3IMPow (ORCPT ); Fri, 13 Sep 2013 11:44:52 -0400 Date: Fri, 13 Sep 2013 15:15:59 +0000 From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Peter Zijlstra cc: Frederic Weisbecker , Andrew Morton , Gilad Ben-Yossef , Thomas Gleixner , Mike Frysinger , linux-kernel@vger.kernel.org, "Paul E. McKenney" , Ingo Molnar Subject: Re: [RFC] Restrict kernel spawning of threads to a specified set of cpus. In-Reply-To: <20130913144008.GF21832@twins.programming.kicks-ass.net> Message-ID: <0000014117e497c1-6b04f29f-c4f8-4178-b69b-aa2233ba343b-000000@email.amazonses.com> References: <20130912141625.GA23357@somewhere> <00000141128d759a-44dcacb6-8f48-4f9b-8381-d14003bd6da1-000000@email.amazonses.com> <20130912143137.GA23839@somewhere> <0000014112a921ae-51d171bf-e8d4-4569-bd20-94dabda2d5ba-000000@email.amazonses.com> <20130912151102.GB23839@somewhere> <0000014112d66287-d0abaeb1-71ff-48a0-8740-f984d47400a7-000000@email.amazonses.com> <20130912183023.GA25386@somewhere> <20130913092553.GL31370@twins.programming.kicks-ass.net> <00000141179a5b1f-b94a8394-9e98-400c-ae7f-59cdcfce60a6-000000@email.amazonses.com> <20130913144008.GF21832@twins.programming.kicks-ass.net> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-SES-Outgoing: 2013.09.13-54.240.9.66 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1008 Lines: 26 On Fri, 13 Sep 2013, Peter Zijlstra wrote: > No, creating a parent for them closes the race. It should also makes it > lots easier to find the kids by using ppid. Ok if all spawning is done from kthreadd then that works. > > A kernel parameter would allow a clean bootup with threads > > starting out on the specific processors we want them to. > > Blergh, no. A kernel should boot, a kernel should allow you to configure > things, a kernel should not be limited to boot time settings. The kernel is not limited but can decide where to place threads. The threads spawned for general user space services are limited to a set of cpus unless there is an explict override. The intend is to keep as much processing as possible away from the notick processors. -- 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/