From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 22 Jan 2001 13:38:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 22 Jan 2001 13:38:12 -0500 Received: from dns-229.dhcp-248.nai.com ([161.69.248.229]:991 "HELO localdomain") by vger.kernel.org with SMTP id ; Mon, 22 Jan 2001 13:38:03 -0500 From: Davide Libenzi Organization: myCIO.com Date: Mon, 22 Jan 2001 10:37:34 -0800 X-Mailer: KMail [version 1.1.95.5] Content-Type: text/plain; charset="us-ascii" Cc: linux-kernel@vger.kernel.org, Ingo Molnar To: Mike Kravetz , lse-tech@lists.sourceforge.net In-Reply-To: <20010122101738.B7427@w-mikek.des.sequent.com> In-Reply-To: <20010122101738.B7427@w-mikek.des.sequent.com> Subject: Re: more on scheduler benchmarks MIME-Version: 1.0 Message-Id: <01012210373402.17926@ewok.dev.mycio.com> Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Monday 22 January 2001 10:30, Mike Kravetz wrote: > Last week while discussing scheduler benchmarks, Bill Hartner > made a comment something like the following "the benchmark may > not even be invoking the scheduler as you expect". This comment > did not fully sink in until this weekend when I started thinking > about changes made to sched_yield() in 2.4.0. (I'm cc'ing Ingo > Molnar because I think he was involved in the changes). If you > haven't taken a look at sys_sched_yield() in 2.4.0, I suggest > that you do that now. > > A result of new optimizations made to sys_sched_yield() is that > calling sched_yield() does not result in a 'reschedule' if there > are no tasks waiting for CPU resources. Therefore, I would claim > that running 'scheduler benchmarks' which loop doing sched_yield() > seem to have little meaning/value for runs where the number of > looping tasks is less than then number of CPUs in the system. Is > that an accurate statement? With this kind of test tasks are always running. If You print the nr_running You'll find that this is exactly ( at least ) the number of tasks You've spawned so the scheduler is always called. - Davide - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/