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 13:18:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 22 Jan 2001 13:18:39 -0500 Received: from gateway.sequent.com ([192.148.1.10]:15584 "EHLO gateway.sequent.com") by vger.kernel.org with ESMTP id ; Mon, 22 Jan 2001 13:18:31 -0500 Date: Mon, 22 Jan 2001 10:17:38 -0800 From: Mike Kravetz To: lse-tech@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org, Ingo Molnar Subject: more on scheduler benchmarks Message-ID: <20010122101738.B7427@w-mikek.des.sequent.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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? If the above is accurate, then I am wondering what would be a good scheduler benchmark for these low task count situations. I could undo the optimizations in sys_sched_yield() (for testing purposes only!), and run the existing benchmarks. Can anyone suggest a better solution? Thanks, -- Mike Kravetz mkravetz@sequent.com IBM Linux Technology Center 15450 SW Koll Parkway Beaverton, OR 97006-6063 (503)578-3494 - 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/