Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261360AbVCaLfr (ORCPT ); Thu, 31 Mar 2005 06:35:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261364AbVCaLfr (ORCPT ); Thu, 31 Mar 2005 06:35:47 -0500 Received: from mx2.elte.hu ([157.181.151.9]:53155 "EHLO mx2.elte.hu") by vger.kernel.org with ESMTP id S261360AbVCaLfh (ORCPT ); Thu, 31 Mar 2005 06:35:37 -0500 Date: Thu, 31 Mar 2005 13:35:27 +0200 From: Ingo Molnar To: kus Kusche Klaus Cc: linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, B.Zolnierkiewicz@elka.pw.edu.pl, Florian Schmidt Subject: Re: 2.6.11, IDE: Strange scheduling behaviour: high-pri RT process not scheduled? Message-ID: <20050331113526.GB27731@elte.hu> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i 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 Content-Length: 867 Lines: 28 * kus Kusche Klaus wrote: > I've written a small test program which enables periodic RTC > interrupts at 8192 Hz and then goes into a loop reading /dev/rtc and > collecting timing statistics (using the rdtscl macro). getting /dev/rtc handling right for latency measurement is ... tricky. The method i'm using under PREEMPT_RT is: chrt -f 84 -p `pidof 'IRQ 0'` chrt -f 95 -p `pidof 'IRQ 8'` ./rtc_wakeup -f 1024 -t 100000 you can get rtc_wakeup from: http://www.affenbande.org/~tapas/wiki/index.php?rtc_wakeup written by Florian Schmidt. do you see high latencies even with rtc_wakeup? 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/