Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753517AbXJ3CjX (ORCPT ); Mon, 29 Oct 2007 22:39:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752610AbXJ3CjQ (ORCPT ); Mon, 29 Oct 2007 22:39:16 -0400 Received: from ozlabs.org ([203.10.76.45]:41874 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752525AbXJ3CjP (ORCPT ); Mon, 29 Oct 2007 22:39:15 -0400 From: Rusty Russell To: Thomas Gleixner Subject: Re: [PATCH] raise tsc clocksource rating Date: Tue, 30 Oct 2007 13:39:23 +1100 User-Agent: KMail/1.9.6 (enterprise 0.20070907.709405) Cc: Glauber de Oliveira Costa , LKML , Jeremy Fitzhardinge , --cc@redhat.com, Ingo Molnar , avi@quramnet.com, kvm-devel@lists.sourceforge.net, John Stultz References: <11936994092607-git-send-email-gcosta@redhat.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200710301339.23628.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1261 Lines: 32 On Tuesday 30 October 2007 09:17:38 Thomas Gleixner wrote: > On Mon, 29 Oct 2007, Glauber de Oliveira Costa wrote: > > CC'ed John and removed glauber@t60.localdomain :) > > > From: Glauber de Oliveira Costa > > > > tsc is very good time source (when it does not have drifts, does not > > change it's frequency, i.e. when it works), so it should have its rating > > raised to a value greater than, or equal 400. > > > > Since it's being a tendency among paravirt clocksources to use values > > around 400, we should declare tsc as even better: So we use 500. > > > > This patch also touches the comments on clocksource.h, which suggests > > that 499 would be a limit on the rating values. > > > > Signed-off-by: Glauber de Oliveira Costa > > Acked-by: Thomas Gleixner No. tsc is very good, it's not perfect. If a paravirt clock registers 400 it really means "pick me over the tsc". That's *why* they use > 400: it's in the documentation. Rusty. - 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/