From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754126AbYIDPgr (ORCPT ); Thu, 4 Sep 2008 11:36:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751472AbYIDPgj (ORCPT ); Thu, 4 Sep 2008 11:36:39 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:40701 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750941AbYIDPgi (ORCPT ); Thu, 4 Sep 2008 11:36:38 -0400 Date: Thu, 4 Sep 2008 17:36:20 +0200 From: Ingo Molnar To: Thomas Gleixner Cc: LKML , Linus Torvalds , Alok Kataria , Arjan van de Veen , "H. Peter Anvin" Subject: Re: [RFC patch 0/4] TSC calibration improvements Message-ID: <20080904153620.GC7120@elte.hu> References: <20080904150339.896115280@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080904150339.896115280@linutronix.de> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Thomas Gleixner wrote: > This patch series addresses following: > > - reduce the calibration time to a useful value > - make decision smarter, when a reference (HPET/PMTIMER) is around > > The first patches are cleanups to prepare for the smarter loop > handling. > > The main change is to reduce the PIT delay value to 10ms, which gives > reasonable results on very slow machines as well. To avoid looping > several times when the machine has a working reference counter > (HPET/pmtimer), we compare the results of the PIT and the reference and > break out of the loop when both match inside of a 10% window. > > For virtualized environments the PIT calibration fails often and the > reference calibration is not reproducible with 10ms. To address this > we check whether the PIT failed two times in a row and make the PIT > loop longer (50ms) for the last try to get a better result for the > reference. > > Most of the machines I tested break out of the loop after the first > try with a stable reproducible result. i've added them to tip/x86/tsc and merged it into tip/master - if there's test success we can merge it into x86/urgent as well and push it into v2.6.27. Any objections to that merge route? Ingo