Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751893AbWJMUpT (ORCPT ); Fri, 13 Oct 2006 16:45:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751895AbWJMUpS (ORCPT ); Fri, 13 Oct 2006 16:45:18 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:53183 "EHLO e32.co.us.ibm.com") by vger.kernel.org with ESMTP id S1751893AbWJMUpQ (ORCPT ); Fri, 13 Oct 2006 16:45:16 -0400 Subject: Re: Keyboard Stuttering From: john stultz To: Lee Revell Cc: Dmitry Torokhov , Frank Sorenson , linux-kernel@vger.kernel.org, David Gerber , Andi Kleen In-Reply-To: <1160669564.24931.37.camel@mindpipe> References: <200610061218.36883.dg-lkml@zapek.com> <1160504714.4973.6.camel@localhost> <1160669564.24931.37.camel@mindpipe> Content-Type: text/plain Date: Fri, 13 Oct 2006 13:45:08 -0700 Message-Id: <1160772309.5457.7.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: 1852 Lines: 43 On Thu, 2006-10-12 at 12:12 -0400, Lee Revell wrote: > On Tue, 2006-10-10 at 11:25 -0700, john stultz wrote: > > On Tue, 2006-10-10 at 13:09 -0400, Dmitry Torokhov wrote: > > > > Same problem here. Intel Core 2 Duo with 2.6.19-rc1 x86_64 SMP. Happens on > > > > 2.6.17 too. I use 'noapic' as a workaround but that disables one of the CPU > > > > core of course. > > > > > > > > I cannot reproduce the problem within the console nor gdm. Only on the X > > > > desktop. > > > > > > > > > > It looks like the only clocksource available on David's box is > > > "jiffies" although the processor shows that it supporst tsc and PM > > > timer is enabled and I think that this is what causes keyboard > > > stuttering in X. See http://bugzilla.kernel.org/show_bug.cgi?id=7291. > > > I believe clocksources is your turf, could you please take a look at > > > this. > > > > Sure thing. I followed up in the bug, but I don't think the clocksource > > code is involved. x86_64 hasn't converted to GENERIC_TIME, so jiffies is > > what we use to increment xtime, but the TSC, ACPI PM, or HPET is used > > for gettimeofday, etc. > > > > I suspect C3 idling is the culprit, since noapic works around the issue. > > Wait, does this mean that Intel's x86-64 implementation has the same > buggy TSC as AMD's? Not the same issue, no.. but the TSCs do halt in lower powersaving modes, which can cause similar results. The new TSC clocksource code on i386 will disqualify itself if those lower powerstates are entered, so it should auto detect and fall back. On x86_64, this logic apparently is sill needed. thanks -john - 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/