From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757217AbYFAJXP (ORCPT ); Sun, 1 Jun 2008 05:23:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752220AbYFAJXB (ORCPT ); Sun, 1 Jun 2008 05:23:01 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:52491 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752035AbYFAJXA (ORCPT ); Sun, 1 Jun 2008 05:23:00 -0400 Subject: Re: [PATCH] sched: Give cpusets exclusive control over sched domains (ie remove cpu_isolated_map) From: Peter Zijlstra To: Max Krasnyansky Cc: Paul Jackson , mingo@elte.hu, linux-kernel@vger.kernel.org, menage@google.com, rostedt@goodmis.org In-Reply-To: <4841A311.2050008@qualcomm.com> References: <1212085023-22284-1-git-send-email-maxk@qualcomm.com> <1212085023-22284-2-git-send-email-maxk@qualcomm.com> <1212085023-22284-3-git-send-email-maxk@qualcomm.com> <20080529173759.ccbaf8ef.pj@sgi.com> <483F3559.1030806@qualcomm.com> <20080529191211.080ec5cf.pj@sgi.com> <483F8178.7040300@qualcomm.com> <20080530015200.f299afed.pj@sgi.com> <4841A311.2050008@qualcomm.com> Content-Type: text/plain Date: Sun, 01 Jun 2008 11:21:52 +0200 Message-Id: <1212312113.24826.63.camel@lappy.programming.kicks-ass.net> Mime-Version: 1.0 X-Mailer: Evolution 2.22.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2008-05-31 at 12:12 -0700, Max Krasnyansky wrote: > > Paul Jackson wrote: > > Max replied: > >>> I did not see your reply. Did you send it to me or lkml? > >> http://marc.info/?l=linux-kernel&m=121207910616332&w=2 > > > > Ah - ok - I got that reply, and then lost track of it. My bad. > > > > Max wrote, in that earlier reply: > >> Since we do not plan on supporting it I'd say lets get rid of it. > > > > This doesn't make sense to me. We don't just decree that we aren't > > planning on supporting something that's already out there and being > > used, and then remove it, on the grounds we aren't supporting it. > > > > Faceless beauracracies can get away with that ... we can do better. > > Ok. Let me ask you this. Would you be ok with a patch that exposes (via sysctl > for example) scheduler balancer mask when cpusets are disabled ? > In other words it will look something like this: > - Rename cpu_isolated_map to sched_balancer_map > - If cpusets are enabled > o balancer map is compiled out or a noop > o isolcpus= boot param is compiled out > > - If cpusets are disabled > o balancer map can be changed via /proc/sys/kernel/sched_balancer_mask > writing to it rebuilds scheduler domains > cpus not in the mask will be put into NULL domain > o isolcpus= boot param is available for compatibility > > Why do this ? > Two reasons. It would not longer be a hack, it simply exposes scheduler > feature that is not otherwise available without cpusets. And there is no > conflict with sched domain management when cpusets are enabled. ie cpuset have > exclusive control on domains). Uhm, might be me but those two answers are not an answer to the question posed. Anyway, no, yuck! - let just get rid of it.