From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Jackson Subject: Re: [PATCH -v2 4/7] RT overloaded runqueues accounting Date: Mon, 22 Oct 2007 21:17:09 -0700 Message-ID: <20071022211709.7be79fea.pj@sgi.com> References: <20071023025900.927578809@goodmis.org> <20071023032916.651749224@goodmis.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, mingo@elte.hu, dmitry.adamushko@gmail.com, ghaskins@novell.com, a.p.zijlstra@chello.nl To: Steven Rostedt , Paul Menage Return-path: Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:49658 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751484AbXJWERO (ORCPT ); Tue, 23 Oct 2007 00:17:14 -0400 In-Reply-To: <20071023032916.651749224@goodmis.org> Sender: linux-rt-users-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org Steven wrote: > +void cpuset_rt_set_overload(struct task_struct *tsk, int cpu) > +{ > + cpu_set(cpu, task_cs(tsk)->rt_overload); > +} Question for Steven: What locks are held when cpuset_rt_set_overload() is called? Questions for Paul Menage: Does 'tsk' need to be locked for the above task_cs() call? Background concern -- one of the things that I like to think has allowed cpusets to be useful to others is the careful documentation of its locking requirements. I hope that the cgroup infrastructure, and the portions of the cpuset code, such as this task_cs() call, that were adapted to work with cgroups, have their locking needs documented as well. I suspect that there is still some presence of stale cpuset locking comments, and perhaps an absence of complete comments on new cgroup locking needs. My recollection is that this is already on your todo list -- I'm just being annoying here ;). -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.925.600.0401