Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 3 Jul 2001 14:52:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 3 Jul 2001 14:52:05 -0400 Received: from e21.nc.us.ibm.com ([32.97.136.227]:57307 "EHLO e21.nc.us.ibm.com") by vger.kernel.org with ESMTP id ; Tue, 3 Jul 2001 14:51:52 -0400 Date: Tue, 3 Jul 2001 11:51:39 -0700 From: Mike Kravetz To: Sasha Pachev Cc: linux-kernel@vger.kernel.org Subject: Re: Strange thread behaviour on 8-way x86 machine Message-ID: <20010703115139.B1128@w-mikek2.des.beaverton.ibm.com> In-Reply-To: <0107031225120K.18621@mysql> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <0107031225120K.18621@mysql>; from sasha@mysql.com on Tue, Jul 03, 2001 at 12:25:12PM -0600 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 03, 2001 at 12:25:12PM -0600, Sasha Pachev wrote: > Hi, > > I have observed a rather strange behaviour doing a multi-threaded CPU > benchmark on an 8-way machine running 2.4.2 SMP kernel. Even when the > priority is reniced to the highest possible value, I am still unable to reach > more than 50% CPU utilization. My benchmark just creates a bunch of threads > with pthread_create(), and then runs a simple integer computation in each > thread. On a dual with 2.4.3 kernel, and a 4-way with 2.4.2 kernel, I am able > to reach full CPU utilization. I haven't had any problem fully utilizing 8 CPUs on 2.4.* kernels. This may seem obvious, but do you have more than 4 CPUs worth of work for the system to do? What is the runqueue length during this benchmark? -- Mike Kravetz mkravetz@sequent.com IBM Linux Technology Center - 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/