From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964959AbWEVAeP (ORCPT ); Sun, 21 May 2006 20:34:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932324AbWEVAeP (ORCPT ); Sun, 21 May 2006 20:34:15 -0400 Received: from mail09.syd.optusnet.com.au ([211.29.132.190]:24998 "EHLO mail09.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S932287AbWEVAeO (ORCPT ); Sun, 21 May 2006 20:34:14 -0400 From: Con Kolivas To: Rene Herman Subject: Re: 2.6.17-rc2+ regression -- audio skipping Date: Mon, 22 May 2006 10:33:48 +1000 User-Agent: KMail/1.9.1 Cc: Lee Revell , Linux Kernel , Linus Torvalds , Mike Galbraith , Ingo Molnar References: <4470CC8F.9030706@keyaccess.nl> <1148247047.20472.78.camel@mindpipe> <44710162.3070406@keyaccess.nl> In-Reply-To: <44710162.3070406@keyaccess.nl> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200605221033.49153.kernel@kolivas.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Monday 22 May 2006 10:10, Rene Herman wrote: > Lee Revell wrote: > > On Sun, 2006-05-21 at 22:24 +0200, Rene Herman wrote: > >> 2.6.17-rc2 (and 3 and 4) make my audio skip. Audio player is ogg123 > >> running in an xterm. Browsing heavy sites (say, eBay) with Firefox > >> 1.5.0.3 gets me audio underruns quickly. This does not happen on > >> 2.6.17-rc1 and earlier (I just tested extensively; quite impossible to > >> generate underruns on -rc1, quickly on -rc2 and later). > >> > >> It's not ALSA; reverted */sound/* from the rc1-rc2 interdiff. It's also > >> not cfq-iosched.c. Any likely culprits in there? (I'm not a GIT user). > > > > I would suspect the scheduler interactivity patches. Please confirm > > this by running ogg123 at nice -20 - do the underruns persist? > > They do persist. Thanks for the hint though -- "sched: fix interactive > task starvation" is the culprit: > > http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=comm >it;h=5ce74abe788a26698876e66b9c9ce7e7acc25413 Good investigative work! Makes sense that falling on the expired array would make for terrible latency for audio apps if your cpu was stretched just the right amount. > Added author and acked-by's to the CC. Mike, this patch is no good for > me. Audio underruns galore, with only ogg123 and firefox (browsing the > GIT tree online is also a nice trigger by the way). > > If I back it out, everything is fine for me again. Back-out attached as > a patch against -rc4. This also backs out your follow-up "don't awaken > RT tasks on expired array" as it was dependant: > > http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=comm >it;h=8a5bc075b8d8cf7a87b3f08fad2fba0f5d13295e > > While looking at the patch I noticed there was +1 difference in the > "limit" value between the macro and the static inline version of > expired_starving() so I experimented with adding that back but that > wasn't it unfortunately. > > I can test patches (preferably versus -rc4) although possibly not quickly. This close to 2.6.17 the safest thing we can and should do is simply back out the patch. -- -ck