Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755817AbYHTSnl (ORCPT ); Wed, 20 Aug 2008 14:43:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752606AbYHTSnb (ORCPT ); Wed, 20 Aug 2008 14:43:31 -0400 Received: from mail9.dslextreme.com ([66.51.199.94]:42755 "HELO mail9.dslextreme.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751550AbYHTSnb (ORCPT ); Wed, 20 Aug 2008 14:43:31 -0400 Message-ID: <48AC65CD.9080108@gawab.com> Date: Wed, 20 Aug 2008 11:43:25 -0700 From: Justin Madru User-Agent: Thunderbird 2.0.0.16 (X11/20080726) MIME-Version: 1.0 To: Peter Zijlstra CC: Greg KH , Ingo Molnar , lkml , Michal Januszewski , Antonino Daplas , Rafael Wysocki , Romano Giannetti , Adrian Bunk , Jeremy Nickurak Subject: Re: [PATCH] sched: disable hrtick implementation References: <48A9BDC0.9070800@gawab.com> <20080819003110.GH9914@elte.hu> <1219127296.10800.357.camel@twins> <20080819092543.GD28713@elte.hu> <1219138380.10800.376.camel@twins> <20080819182222.GA25576@suse.de> <48AB1F49.6040207@gawab.com> <20080819194428.GA9997@suse.de> <48AB4F2B.9070405@gawab.com> <1219217091.10800.395.camel@twins> In-Reply-To: <1219217091.10800.395.camel@twins> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3202 Lines: 90 Peter Zijlstra wrote: > On Tue, 2008-08-19 at 15:54 -0700, Justin Madru wrote: >> The hrtick implementation in 2.6.25 and .26 has been known to cause boot >> problems with at least Intel GMA cards. see: >> >> https://bugs.freedesktop.org/show_bug.cgi?id=15602 >> http://bugzilla.kernel.org/show_bug.cgi?id=10892 >> >> A full fix to hrtick went into 2.6.27 >> (31656519e132f6612584815f128c83976a9aaaef), >> but that fix is too intrusive to backport. Henceforth, we default to >> disable hrtick. > > Thing is, I'm still not understanding how, or if, the old code is wrong. > > That said, this will paper over the problem just fine, and as its old > kernels we're talking about I don't particularly care. Fair enough. All I know is that right when I started testing .25-rc1 I kept getting a garbled boot splash, blank screen, and even lock-ups during booting. It seemed to be that if I disabled the boot splash and/or started x manually the problem would rarely occur. So, maybe the first change to hrtick just exposed a bug in the boot splash or the x server. If that's true then, I don't get why right when .27-rc1 was out all the boot problems were gone. Bisecting found both commits (introduce and fix) to be about hrtick. So maybe the commit that introduced my bug wasn't completely wrong, but at least it was not right enough because of the second commit was trying to fix something -- right? And the kernel still boots with hrtick disabled, I tested that. > Just occured to me that a Kconfig change that always makes > CONFIG_SCHED_HRTICK not set will also do. >> Signed-off-by: Justin Madru >> Tested-by: Justin Madru >> Cc: Peter Zijlstra >> Cc: Ingo Molnar >> >> --- a/kernel/sched_features.h >> +++ b/kernel/sched_features.h >> @@ -4,7 +4,7 @@ >> SCHED_FEAT(AFFINE_WAKEUPS, 1) >> SCHED_FEAT(CACHE_HOT_BUDDY, 1) >> SCHED_FEAT(SYNC_WAKEUPS, 1) >> -SCHED_FEAT(HRTICK, 1) >> +SCHED_FEAT(HRTICK, 0) >> SCHED_FEAT(DOUBLE_TICK, 0) >> SCHED_FEAT(NORMALIZED_SLEEPER, 1) >> SCHED_FEAT(DEADLINE, 1) >> Wouldn't disabling CONFIG_HIGH_RES_TIMERS (in the menu) also disable CONFIG_SCHED_HRTICK? In any case what about this patch below? The hrtick implementation in 2.6.25 and .26 has been known to cause boot problems with at least Intel GMA cards. see: https://bugs.freedesktop.org/show_bug.cgi?id=15602 http://bugzilla.kernel.org/show_bug.cgi?id=10892 A full fix to hrtick went into 2.6.27 (31656519e132f6612584815f128c83976a9aaaef), but that fix is too intrusive to backport. Henceforth, we default to disable hrtick. Signed-off-by: Justin Madru Tested-by: Justin Madru Cc: Peter Zijlstra Cc: Ingo Molnar --- a/kernel/Kconfig.hz +++ b/kernel/Kconfig.hz @@ -55,4 +55,5 @@ default 1000 if HZ_1000 config SCHED_HRTICK - def_bool HIGH_RES_TIMERS && X86 + bool + default n -- 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/