From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264925AbTLTQRh (ORCPT ); Sat, 20 Dec 2003 11:17:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264927AbTLTQRh (ORCPT ); Sat, 20 Dec 2003 11:17:37 -0500 Received: from port-212-202-159-243.reverse.qsc.de ([212.202.159.243]:59009 "EHLO mail.onestepahead.de") by vger.kernel.org with ESMTP id S264925AbTLTQR2 (ORCPT ); Sat, 20 Dec 2003 11:17:28 -0500 Subject: Re: 2.6 vs 2.4 regression when running gnomemeeting From: Christian Meder To: Ingo Molnar Cc: linux-kernel@vger.kernel.org In-Reply-To: <20031220111917.GA18267@elte.hu> References: <1071864709.1044.172.camel@localhost> <1071885178.1044.227.camel@localhost> <3FE3B61C.4070204@cyberone.com.au> <200312201355.08116.kernel@kolivas.org> <1071891168.1044.256.camel@localhost> <3FE3C6FC.7050401@cyberone.com.au> <1071893802.1363.21.camel@localhost> <3FE3D0CB.603@cyberone.com.au> <1071897314.1363.43.camel@localhost> <20031220111917.GA18267@elte.hu> Content-Type: text/plain Message-Id: <1071937040.1025.27.camel@localhost> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.5 Date: Sat, 20 Dec 2003 17:17:21 +0100 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2003-12-20 at 12:19, Ingo Molnar wrote: > * Christian Meder wrote: > > > That would leave me with two possibilities: 2.6. is doing something > > different in the gnomemeeting case or gnomemeeting is doing something > > different in the 2.6 case. A cursory look at the gnomemeeting sources > > didn't give me the impression that it's doing anything which would be > > affected by 2.6 deployment but I'll ask on the gnomemeeting-devel list > > for advice. > > yep, i've looked at the source too and it doesnt do anything that > changed in 2.6 from an interactivity POV. > > To analyze the precise workload that hurts gnomemeeting, could you try > the following workload: > > main() > { > for (;;) sched_yield(); > } > > and run 1-2 copies of such a load-generator - does it degrade > gnome-meeting audio just as much as eg. a kernel compile does? > > as a next step, does the following degrade gnomemeeting?: > > main() > { > for (;;) ; > } > > my guess would be that if the yield() one degrades interactivity too > then this is unlikely to be somehow related to the scheduler proper. > > If it doesnt degrade but the simple non-yield loop above does, then it's > probably something scheduling related in the sound architecture. (eg. > use of yield() by some codepath of the sound drivers - although they > dont seem to be doing anything like this.) > > If neither of these workloads degrades gnomemeeting, but a kernel-make > does, then it's the interactivity estimator. Ok, the results are in. Running up to three yield-loops doesn't degrade gnomemeeting. Running one non-yield loop does degrade gnomemeeting _very_ slightly. Adding a second non-yield loop has approximately the same stuttering effect as a kernel compile. Adding a third non-yield loop makes gnomemeeting totally unusable. All these tests were done with Nick's scheduler patch. If I should retry with stock 2.6.0 just tell me. Sound driver is by the way snd_es1968 in ALSA and maestro in OSS. Christian -- Christian Meder, email: chris@onestepahead.de What's the railroad to me ? I never go to see Where it ends. It fills a few hollows, And makes banks for the swallows, It sets the sand a-blowing, And the blackberries a-growing. (Henry David Thoreau)