Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756008AbXLHPjQ (ORCPT ); Sat, 8 Dec 2007 10:39:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751883AbXLHPjF (ORCPT ); Sat, 8 Dec 2007 10:39:05 -0500 Received: from vs166246.vserver.de ([62.75.166.246]:56210 "EHLO vs166246.vserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751848AbXLHPjD (ORCPT ); Sat, 8 Dec 2007 10:39:03 -0500 From: Michael Buesch To: Ingo Molnar Subject: Re: [PATCH] scheduler: fix x86 regression in native_sched_clock Date: Sat, 8 Dec 2007 16:36:45 +0100 User-Agent: KMail/1.9.6 Cc: Mark Lord , Guillaume Chazarain , stefano.brivio@polimi.it, Nick Piggin , Robert Love , linux-kernel@vger.kernel.org, Dave Jones , "Rafael J. Wysocki" , Thomas Gleixner , Andrew Morton , Len Brown References: <20071207084559.GA11162@elte.hu> <200712081627.45937.mb@bu3sch.de> <20071208153327.GC30270@elte.hu> In-Reply-To: <20071208153327.GC30270@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200712081636.45828.mb@bu3sch.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1859 Lines: 53 On Saturday 08 December 2007 16:33:27 Ingo Molnar wrote: > > * Michael Buesch wrote: > > > On Saturday 08 December 2007 16:13:41 Ingo Molnar wrote: > > > > > > * Mark Lord wrote: > > > > > > > Ingo Molnar wrote: > > > >> ... > > > >> thanks. I do get the impression that most of this can/should wait until > > > >> 2.6.25. The patches look quite dangerous. > > > > .. > > > > > > > > I confess to not really trying hard to understand everything in this > > > > thread, but the implication seems to be that this bug might affect > > > > udelay() and possibly jiffies ? > > > > > > no, it cannot affect jiffies. (jiffies was a red herring all along) > > > > > > udelay() cannot be affected either - sched_clock() has no effect on > > > udelay(). _But_, when there are TSC problems then tsc based udelay() > > > suffers too so the phenomenons may _seem_ related. > > > > What about msleep()? I suspect problems in b43 because of this issue. > > msleep() returning too early. Is that possible with this bug? > > i cannot see how. You can verify msleep by running something like this: > > while :; do time usleep 111000; done > > you should see a steady stream of: > > real 0m0.113s > real 0m0.113s > real 0m0.113s > > (on an idle system). If it fluctuates, with occasional longer delays, > there's some timer problem present. Does the sleeping and timing use different time references? I mean, if it uses the same reference and that reference does fluctuate you won't see it in the result. But anyway, Stefano. Can you test this? -- Greetings Michael. -- 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/