From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753040Ab0INJxO (ORCPT ); Tue, 14 Sep 2010 05:53:14 -0400 Received: from www.tglx.de ([62.245.132.106]:33081 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751581Ab0INJxL (ORCPT ); Tue, 14 Sep 2010 05:53:11 -0400 Date: Tue, 14 Sep 2010 11:52:57 +0200 (CEST) From: Thomas Gleixner To: Vasily Khoruzhick cc: Venkatesh Pallipadi , Jesse Barnes , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: Interrupt latency on some 945GM platforms In-Reply-To: <201009141109.41596.anarsoul@gmail.com> Message-ID: References: <201009132336.17310.anarsoul@gmail.com> <201009140104.03135.anarsoul@gmail.com> <201009141109.41596.anarsoul@gmail.com> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="-1463795968-974713557-1284457979=:2416" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1463795968-974713557-1284457979=:2416 Content-Type: TEXT/PLAIN; charset=utf-8 Content-Transfer-Encoding: 8BIT On Tue, 14 Sep 2010, Vasily Khoruzhick wrote: > В сообщении от 14 of September 2010 03:55:32 автор Venkatesh Pallipadi > написал: > > > Whats the clockevent in this case ("Tick Device" section of > > /proc/timer_list). clocksource= option only changes the clocksource used > > to maintain > > timeofday. But, timer interrupt (clockevent) source will not change. > > Wondering how just the clocksource change is making the diff here.. > > > > Also, if clocksource tsc has a higher rating than HPET. The reason > > HPET is getting used as clocksource in the first place seems to be due > > to TSC is not a dependable clocksource on this platform (may be it > > stops in C3). So, I am not sure forcing it to tsc will be a good > > thing. May be clocksource=acpi_pm is a better thing to try. > > > > Thanks, > > Venki > > I investigated it a bit and found out that single nohz=off option helps. Just > changing clocksource doesn't help, but it works smoothly with any clocksource > with nohz=off. So, it seems that something wrong with intel driver while > system is in tickless mode. Can you try with NOHZ enabled and the following on the kernel command line: processor.max_cstate=1 Make sure that CONFIG_ACPI_PROCESSOR is set to "y" and not to "m" If that works, then try processor.max_cstate=2 Thanks, tglx ---1463795968-974713557-1284457979=:2416--