Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756133AbYGZPkw (ORCPT ); Sat, 26 Jul 2008 11:40:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752560AbYGZPko (ORCPT ); Sat, 26 Jul 2008 11:40:44 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:41789 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752332AbYGZPko (ORCPT ); Sat, 26 Jul 2008 11:40:44 -0400 Date: Sat, 26 Jul 2008 17:40:29 +0200 From: Ingo Molnar To: Martin Wilck Cc: Cyrill Gorcunov , Thomas Gleixner , "linux-kernel@vger.kernel.org" , "H. Peter Anvin" , "Wichert, Gerhard" , "Maciej W. Rozycki" Subject: Re: [PATCH] x86 (64): make calibrate_APIC_clock() SMI-safe (take 3) Message-ID: <20080726154029.GA15945@elte.hu> References: <48889C14.4070408@fujitsu-siemens.com> <4889968E.6020000@fujitsu-siemens.com> <20080725100844.GA16698@lenovo> <4889C723.7050402@fujitsu-siemens.com> <20080725125950.GA28466@lenovo> <4889D767.5050709@fujitsu-siemens.com> <20080725134831.GB28466@lenovo> <4889DCA4.4010800@fujitsu-siemens.com> <20080725150104.GD28466@lenovo> <4889ED91.7050800@fujitsu-siemens.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4889ED91.7050800@fujitsu-siemens.com> 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 Content-Length: 1327 Lines: 31 * Martin Wilck wrote: > [PATCH] x86 (64): make calibrate_APIC_clock() SMI-safe (take 3) > > Non-maskable asynchronous events (e.g. SMIs) which occur during the > APIC timer calibration can cause timer miscalibrations, sometimes by > large amounts. This patch fixes this by making sure that no > significant interruption occurs between APIC and TSC reads. SMIs may > still occur at some stage in the calibration loop, causing the loop to > last longer than intended. This doesn't matter though, as long as the > start and end values are both taken simultaneously. > > Changed wrt take 2: Use max. possible start value for the APIC timer > to avoid underflow. > > Signed-off-by: Martin Wilck > Signed-off-by: Gerhard Wichert > > --- arch/x86/kernel/apic_64.c 2008-07-25 15:39:51.000000000 +0200 > +++ arch/x86/kernel/apic_64.c.new 2008-07-25 15:55:08.000000000 +0200 nice - could you please implement it symmetrically on 32-bit APIC calibration as well? Ingo -- 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/