Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751423AbVJKI4W (ORCPT ); Tue, 11 Oct 2005 04:56:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751425AbVJKI4W (ORCPT ); Tue, 11 Oct 2005 04:56:22 -0400 Received: from gateway-1237.mvista.com ([12.44.186.158]:37115 "EHLO hermes.mvista.com") by vger.kernel.org with ESMTP id S1751423AbVJKI4V (ORCPT ); Tue, 11 Oct 2005 04:56:21 -0400 Subject: Re: Latency data - 2.6.14-rc3-rt13 From: Sven-Thorsten Dietrich To: Mark Knecht Cc: Daniel Walker , linux-kernel@vger.kernel.org, Ingo Molnar , Lee Revell In-Reply-To: <5bdc1c8b0510102045u7e4bc9eeld5b690b5e96c4a5f@mail.gmail.com> References: <5bdc1c8b0510101316k23ff64e2i231cdea7f11e8553@mail.gmail.com> <1128977359.18782.199.camel@c-67-188-6-232.hsd1.ca.comcast.net> <5bdc1c8b0510101412n714c4798v1482254f6f8e0386@mail.gmail.com> <5bdc1c8b0510101428o475d9dbct2e9bdcc6b46418c9@mail.gmail.com> <1128980674.18782.211.camel@c-67-188-6-232.hsd1.ca.comcast.net> <5bdc1c8b0510101509w4c74028apb6e69746b1b8b65b@mail.gmail.com> <1128983301.18782.215.camel@c-67-188-6-232.hsd1.ca.comcast.net> <5bdc1c8b0510101633lc45fbf8gd2677e5646dc6f93@mail.gmail.com> <5bdc1c8b0510101649s221ab437scc49d6a49269d6b@mail.gmail.com> <5bdc1c8b0510102045u7e4bc9eeld5b690b5e96c4a5f@mail.gmail.com> Content-Type: text/plain Date: Tue, 11 Oct 2005 01:56:19 -0700 Message-Id: <1129020979.10291.6.camel@imap.mvista.com> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1679 Lines: 52 On Mon, 2005-10-10 at 20:45 -0700, Mark Knecht wrote: > On 10/10/05, Mark Knecht wrote: > > > > ( softirq-timer/0-3 |#0): new 3997 us maximum-latency critical section. > > So the root cause of this 4mS delay is the 250Hz timer. If I change > the system to use the 1Khz timer then the time in this section drops, > as expected, to 1mS. > > ( softirq-timer/0-3 |#0): new 998 us maximum-latency critical section. > => started at timestamp 121040020: > => ended at timestamp 121041019: > > So, thinking very interesting here I think. > Maximum preemption latencies near the timer period are sometimes indicative of mismatched preempt_disable/preempt_enable pairs in the code. Usually the scheduler warns about that on the console, however. Sven > Back to the drawing board as to my xruns. > > - Mark > - > 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/ -- *********************************** Sven-Thorsten Dietrich Real-Time Software Architect MontaVista Software, Inc. 1237 East Arques Ave. Sunnyvale, CA 94085 Phone: 408.992.4515 Fax: 408.328.9204 http://www.mvista.com Platform To Innovate *********************************** - 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/