Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933022Ab1EYPCW (ORCPT ); Wed, 25 May 2011 11:02:22 -0400 Received: from mail.digidescorp.com ([66.244.163.200]:17044 "EHLO mail.digidescorp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932994Ab1EYPCV (ORCPT ); Wed, 25 May 2011 11:02:21 -0400 X-Greylist: delayed 323 seconds by postgrey-1.27 at vger.kernel.org; Wed, 25 May 2011 11:02:21 EDT DomainKey-Signature: a=rsa-sha1; s=MDaemon; d=digidescorp.com; c=simple; q=dns; h=from:message-id; b=09NtWKlKTYLnTnBziCsXsynIxLq+uSWd+/CnFY2i3Lc69rkjoFpqfQmp8KDt csH+zJHGBKcKmFoXVsD4BF6/4EzkOS6ejsD3qLfyJoUUsR4a3/kh5oSkQ TVjqIQJGh9HTGZ2a6myr8xIqQfI0PuB4eogAm0/RRbtjP/Y/7tTd9w=; X-Spam-Processed: mail.digidescorp.com, Wed, 25 May 2011 09:56:56 -0500 X-Authenticated-Sender: steve@digidescorp.com X-Return-Path: prvs=1126de5331=steve@digidescorp.com X-Envelope-From: steve@digidescorp.com X-MDaemon-Deliver-To: linux-kernel@vger.kernel.org Subject: Re: [Bug #23902] 2.6.37-rc3 massive interactivity regression on ARM From: "Steven J. Magnani" To: andi@firstfloor.org, LKML Cc: rjw@sisk.pl, stable@kernel.org, a.p.zijlstra@chello.nl Content-Type: text/plain; charset="UTF-8" Date: Wed, 25 May 2011 09:56:51 -0500 Message-ID: <1306335411.2643.21.camel@iscandar.digidescorp.com> Mime-Version: 1.0 X-Mailer: Evolution 2.32.2 (2.32.2-1.fc14) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2273 Lines: 55 Andi - This bug appears to have crept into 2.6.35.12 via a3fe22ee824895aafdc1b788e19c081a2e6dd9da and is still present in 2.6.35.13. Mainline patch fe44d62122829959e960bc699318d58966922a69 (sched: Fix the irqtime code to deal with u64 wraps) seems to fix my system although I recommend also applying 8e92c20183ed0579d94501311b81c42b65cb2129 (sched: Fix the irqtime code for 32bit). Any stable releases that have picked up 305e6835e05513406fa12820e40e4a8ecb63743c (sched: Do not account irq time to current task) should probably also apply these. Before I could get these patches to apply to 2.6.35.13 I had to tweak sched.c:update_rq_clock() to match f26f9aff6aaf67e9a430d16c266f91b13a5bff64 (Sched: fix skip_clock_update optimization). That patch was applied to 2.6.35-longterm, except for the update_rq_clock() portion. I believe that was because that portion depended on a patch from Ventakesh that wasn't applied until later. It looks like the logic that ended up in 2.6.35.12 was slightly different than in mainline; I'm not familiar enough with the scheduler details to know what the effects would be. ------------------------------------------------------------------------ Signed-off-by: Steven J. Magnani --- diff -uprN a/kernel/sched.c b/kernel/sched.c --- a/kernel/sched.c 2011-05-25 09:39:05.200320708 -0500 +++ b/kernel/sched.c 2011-05-25 09:39:27.990238065 -0500 @@ -654,8 +654,10 @@ inline void update_rq_clock(struct rq *r int cpu = cpu_of(rq); u64 irq_time; - if (!rq->skip_clock_update) - rq->clock = sched_clock_cpu(cpu_of(rq)); + if (rq->skip_clock_update) + return; + + rq->clock = sched_clock_cpu(cpu); irq_time = irq_time_cpu(cpu); if (rq->clock - irq_time > rq->clock_task) rq->clock_task = rq->clock - irq_time; ------------------------------------------------------------------------ Steven J. Magnani "I claim this network for MARS! www.digidescorp.com Earthling, return my space modulator!" #include -- 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/