Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966024AbWKKLMR (ORCPT ); Sat, 11 Nov 2006 06:12:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966118AbWKKLMQ (ORCPT ); Sat, 11 Nov 2006 06:12:16 -0500 Received: from www.osadl.org ([213.239.205.134]:6308 "EHLO mail.tglx.de") by vger.kernel.org with ESMTP id S966024AbWKKLMP (ORCPT ); Sat, 11 Nov 2006 06:12:15 -0500 Subject: Re: [patch 13/19] GTOD: Mark TSC unusable for highres timers From: Thomas Gleixner Reply-To: tglx@linutronix.de To: Andi Kleen Cc: Andrew Morton , Ingo Molnar , john stultz , LKML , Len Brown , Arjan van de Ven , Roman Zippel In-Reply-To: <200611101029.59251.ak@suse.de> References: <20061109233030.915859000@cruncher.tec.linutronix.de> <20061110085728.GA14620@elte.hu> <20061110011336.008840cf.akpm@osdl.org> <200611101029.59251.ak@suse.de> Content-Type: text/plain Date: Sat, 11 Nov 2006 12:14:37 +0100 Message-Id: <1163243677.8335.245.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1340 Lines: 32 On Fri, 2006-11-10 at 10:29 +0100, Andi Kleen wrote: > > But that's different. > > > > We're limping along in a semi-OK fashion with the TSC. But now Thomas is > > proposing that we effectively kill it off for all x86 because of hrtimers. > > I'm totally against that. I'm working on that. The general disable is indeed overkill. All I need to prevent is to switch over to highres/dyntick in case that there is no fallback (e.g. pm_timer) available. Else I end up in a circular dependency as the emulated tick depends on the monotonic clock. > > And afaict the reason for that is that we're using jiffies to determine if > > the TSC has gone bad, and that test is getting false positives. > > The i386 clocksource had always trouble with that. e.g. I have a box > where the TSC works perfectly fine on a 64bit kernel, but since the new i386 > clocksource code is in it always insists on disabling it shortly after boot. > My guess is that some of the checks in there are just broken and need > to be fixed. It's the unconditional mark_unstable call in ACPI C2 state. /me looks. tglx - 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/