From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261944AbULGVrw (ORCPT ); Tue, 7 Dec 2004 16:47:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261948AbULGVrw (ORCPT ); Tue, 7 Dec 2004 16:47:52 -0500 Received: from mx1.elte.hu ([157.181.1.137]:59523 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S261949AbULGVrt (ORCPT ); Tue, 7 Dec 2004 16:47:49 -0500 Date: Tue, 7 Dec 2004 22:47:15 +0100 From: Ingo Molnar To: Gene Heskett Cc: linux-kernel@vger.kernel.org, Eran Mann Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm2-V0.7.32-2 Message-ID: <20041207214715.GB12879@elte.hu> References: <41B5C038.1090501@mrv.com> <20041207153720.GA20712@elte.hu> <200412071340.42731.gene.heskett@verizon.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200412071340.42731.gene.heskett@verizon.net> User-Agent: Mutt/1.4.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Gene Heskett wrote: > I'd like to report a slight improvement in the reports from tvtime > while running 32-6 with full preemtion turned on, cfq scheduler: > > ------ > Dec 7 13:29:39 coyote kernel: wow! That was a 15 millisec bump > Dec 7 13:29:39 coyote kernel: `IRQ 8'[838] is being piggy. > need_resched=0, cpu=0 > Dec 7 13:29:39 coyote kernel: Read missed before next interrupt > ----- > Each second of the log contains about 27 of these, so its pretty > steady. Picture looks pretty good though. > > Although, that particular snip was taken from the log while I was > *not* on the same screen as tvtime. Switching back it its screen > returned the slip times to the 22 millisecond area. [...] could enable WAKEUP_TIMING and LATENCY_TRACING, boot into the new kernel and do: echo 0 > /proc/sys/kernel/preempt_max_latency then you'll get the worst-case trace in /proc/latency_trace. Does it show any millisecs-range latencies? also, do this: chrt -f 90 -p `pidof 'IRQ 8'` chrt -f 91 -p `pidof 'IRQ 0'` to make sure IRQ8 doesnt get preempted by other stuff. How often do you get the rtc histogram in the syslog? Does tvtime use /dev/rtc for normal operations perhaps? If yes then you might want to disable RTC_HISTOGRAM. Ingo