Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753383AbZCJE17 (ORCPT ); Tue, 10 Mar 2009 00:27:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751237AbZCJE1u (ORCPT ); Tue, 10 Mar 2009 00:27:50 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:41823 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751099AbZCJE1t (ORCPT ); Tue, 10 Mar 2009 00:27:49 -0400 Date: Mon, 9 Mar 2009 21:26:48 -0700 (PDT) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: Jesper Krogh cc: john stultz , Thomas Gleixner , Linux Kernel Mailing List , Len Brown Subject: Re: Linux 2.6.29-rc6 In-Reply-To: <49B57F3D.5030008@krogh.cc> Message-ID: References: <49A6F39F.9040801@krogh.cc> <49A6FEE2.90700@krogh.cc> <1f1b08da0902261319k7a60d80xaafc1101facfd2d9@mail.gmail.com> <49A70B24.6090706@krogh.cc> <1235685269.6811.11.camel@localhost.localdomain> <1235687483.6811.26.camel@localhost.localdomain> <49A78C79.304@krogh.cc> <1235766936.7402.5.camel@localhost.localdomain> <49ABACA0.3090300@krogh.cc> <1236029277.7756.0.camel@localhost.localdomain> <49ACC853.8070205@krogh.cc> <1236110026.6068.18.camel@localhost> <49AD90E2.7050209@krogh.cc> <1236118969.6068.87.camel@localhost> <49AE9EA4.2080500@krogh.cc> <49AECA3B.5030503@krogh.cc> <1236193075.3793.63.camel@jstultz-laptop> <1236220759.6863.7.camel@localhost.localdomain> <1236221530.6863.9.camel@localhost.localdomain> <49B57F3D.5030008@krogh.cc> 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 Content-Length: 1254 Lines: 34 On Mon, 9 Mar 2009, Jesper Krogh wrote: > > First boot. > [ 0.000000] ref_freq: 2311825 pit_freq: 2310386 > Second boot: > [ 0.000000] ref_freq: 2311803 pit_freq: 2310190 > Third boot: > [ 0.000000] ref_freq: 2311824 pit_freq: 2310080 > Fourth boot: > [ 0.000000] ref_freq: 2311831 pit_freq: 2310130 It's really quite impressively stable, but the fast-PIT calibration frequency is reliably about 3/4 of a promille low. Or, put another way, the TSC difference over the pit calibration is just a _tad_ too small compared to the value we'd expect if that loop of pit_expect_msb() would really run at the expected delay of a 1.193182MHz clock divided by 256. And it's stable in that it really always seems to be off by a very similar amount. It's not moving around very much. I also wonder why it seems to happen mainly just to _you_. There's absolutely nothing odd in your system, neither a slow CPU or anything else that would stand out. Grr. Very annoyingly non-obvious. Linus -- 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/