From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762500AbZEHFWW (ORCPT ); Fri, 8 May 2009 01:22:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752826AbZEHFWN (ORCPT ); Fri, 8 May 2009 01:22:13 -0400 Received: from vms173003pub.verizon.net ([206.46.173.3]:10094 "EHLO vms173003pub.verizon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752052AbZEHFWM (ORCPT ); Fri, 8 May 2009 01:22:12 -0400 Date: Fri, 08 May 2009 01:21:46 -0400 (EDT) From: Len Brown X-X-Sender: lenb@localhost.localdomain To: Steven Rostedt Cc: LKML , Ingo Molnar , Thomas Gleixner , john stultz Subject: Re: regression in TSC unstable? In-reply-to: Message-id: References: User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-version: 1.0 Content-type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 8 May 2009, Steven Rostedt wrote: > The ring-buffer-benchmark module creates a producer and consumer and loops > on do_gettimeofday until it hits about 10 seconds. Then it calculates the > number of events recorded / time running. > > After Ingo merged Linus's latest merged what into what? are you referring to the upstream kernel or something else? > my tests when from 330ns per entry to > 880ns. After bisecting it I came down to this change: > > commit a71e4917dc0ebbcb5a0ecb7ca3486643c1c9a6e2 > Author: Len Brown > Date: Tue Apr 21 00:50:11 2009 -0400 > > ACPI: idle: mark_tsc_unstable() at init-time, not run-time > > > I've never had a problem with the TSC with this box before. It passes the > synchronization phase, and until this commit, the TSC never was marked as > unstable. > > Should it now be unstable? Or is this a false positive? If you revert that patch the issue goes away? Does your Xeon even export any C-states? (cat /proc/acpi/processor/*/power) does your dmesg before or afer the patch actually print "TSC halts in idle"? thanks, -Len > # cat /proc/cpuinfo > processor : 0 > vendor_id : GenuineIntel > cpu family : 15 > model : 4 > model name : Intel(R) Xeon(TM) CPU 2.80GHz > stepping : 1 > cpu MHz : 2793.272 > cache size : 1024 KB > physical id : 0 > siblings : 2 > core id : 0 > cpu cores : 1 > apicid : 0 > initial apicid : 0 > fpu : yes > fpu_exception : yes > cpuid level : 5 > wp : yes > flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca > cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx > lm constant_tsc pebs bts pni dtes64 monitor ds_cpl cid cx16 xtpr > bogomips : 5586.54 > clflush size : 64 > cache_alignment : 128 > address sizes : 36 bits physical, 48 bits virtual > power management: > > Anything else I might need to know? > > -- Steve > > -- > 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/ >