Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754107AbXFKOoV (ORCPT ); Mon, 11 Jun 2007 10:44:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752590AbXFKOoK (ORCPT ); Mon, 11 Jun 2007 10:44:10 -0400 Received: from e2.ny.us.ibm.com ([32.97.182.142]:42816 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752483AbXFKOoI (ORCPT ); Mon, 11 Jun 2007 10:44:08 -0400 Date: Mon, 11 Jun 2007 07:44:02 -0700 From: "Paul E. McKenney" To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, Thomas Gleixner , Dinakar Guniguntala Subject: Re: v2.6.21.4-rt11 Message-ID: <20070611144401.GA9102@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20070609210507.GA29194@elte.hu> <20070611011954.GG27982@linux.vnet.ibm.com> <20070611073634.GB32446@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070611073634.GB32446@elte.hu> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1645 Lines: 42 On Mon, Jun 11, 2007 at 09:36:34AM +0200, Ingo Molnar wrote: > > * Paul E. McKenney wrote: > > > 2.6.21.4-rt12 boots on 4-CPU Opteron and passes several hours of > > rcutorture. However, if I simply do "modprobe rcutorture", the kernel > > threads do not spread across the CPUs as I would expect them to, even > > given CFS. Instead, the readers all stack up on a single CPU, and I > > have to use the "taskset" command to spread them out manually. Is > > there some config parameter I am missing out on? > > hm, what affinity do they start out with? Could they all be pinned to > CPU#0 by default? They start off with affinity masks of 0xf on a 4-CPU system. I would expect them to load-balance across the four CPUs, but they stay all on the same CPU until long after I lose patience (many minutes). Since there are eight readers, I use the following commands: taskset -p 3 pid1 taskset -p 3 pid2 taskset -p 6 pid3 taskset -p 6 pid4 taskset -p c pid5 taskset -p c pid6 taskset -p 9 pid7 taskset -p 9 pid8 where the "pidn" are all replaced by the pids of the torture readers. Before I do this, the processes are all sharing a single CPU. After I do this, they are spread reasonably nicely over the CPUs. I do need to allow some migration in order to fully test the realtime RCU variants in the various preemption scenarios. Thanx, Paul - 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/