Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1945967AbWANBjh (ORCPT ); Fri, 13 Jan 2006 20:39:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1945969AbWANBjh (ORCPT ); Fri, 13 Jan 2006 20:39:37 -0500 Received: from e36.co.us.ibm.com ([32.97.110.154]:30652 "EHLO e36.co.us.ibm.com") by vger.kernel.org with ESMTP id S1945967AbWANBjg (ORCPT ); Fri, 13 Jan 2006 20:39:36 -0500 Subject: RE: Dual core Athlons and unsynced TSCs From: john stultz To: Lee Revell Cc: Steven Rostedt , Thomas Gleixner , Ingo Molnar , Roger Heflin , "'linux-kernel'" In-Reply-To: <1137202039.1408.42.camel@mindpipe> References: <1137168254.7241.32.camel@localhost.localdomain> <1137174463.15108.4.camel@mindpipe> <1137174848.15108.11.camel@mindpipe> <1137178506.15108.38.camel@mindpipe> <1137182991.8283.7.camel@localhost.localdomain> <1137198221.11300.21.camel@cog.beaverton.ibm.com> <1137201012.6727.1.camel@localhost.localdomain> <1137201250.1408.39.camel@mindpipe> <1137201821.11300.30.camel@cog.beaverton.ibm.com> <1137202039.1408.42.camel@mindpipe> Content-Type: text/plain Date: Fri, 13 Jan 2006 17:39:33 -0800 Message-Id: <1137202773.11300.37.camel@cog.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1636 Lines: 42 On Fri, 2006-01-13 at 20:27 -0500, Lee Revell wrote: > On Fri, 2006-01-13 at 17:23 -0800, john stultz wrote: > > On Fri, 2006-01-13 at 20:14 -0500, Lee Revell wrote: > > > On Fri, 2006-01-13 at 20:10 -0500, Steven Rostedt wrote: > > > > > > > > Thanks, I'll add that to my list of tests too. > > > > > > > > Oh and 2.6.15 passed as well (with clock=pmtmr) > > > > > > It really seems like it would fail if you gave it enough time due to the > > > rdtsc in monotonic_clock()... > > > > Currently monotonic_clock()is only used by the hangcheck-timer, and is > > not used by gettimeofday/clock_gettime (even w/ CLOCK_MONOTONIC). > > > > So there may still be an issue there w/ the hangcheck-timer(for x86-64, > > on i386 the acpi pm timer can be used for monotonic_clock), but its > > doesn't affect the time related userland interfaces. > > OK so the last question is how do we make sure the kernel uses the > clock=pmtmr behavior by default on those machines? This is as I understand it: With 2.6.15 on x86-64: If available, alternate timesources (HPET, ACPI PM) will be used if available on AMD SMP systems. (clock= is i386 only) With 2.6.15 on i386: If CONFIG_X86_PM_TIMER is enabled, and available it is the preferred clocksource over the TSC. Some distros have changed this priority causing the TSC to be preferred. In these cases clock=pmtmr is needed. How's that? -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/