Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263531AbUKAOGV (ORCPT ); Mon, 1 Nov 2004 09:06:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263065AbUKAOGS (ORCPT ); Mon, 1 Nov 2004 09:06:18 -0500 Received: from mx1.elte.hu ([157.181.1.137]:43144 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S265189AbUKAOF1 (ORCPT ); Mon, 1 Nov 2004 09:05:27 -0500 Date: Mon, 1 Nov 2004 15:06:30 +0100 From: Ingo Molnar To: Florian Schmidt Cc: Lee Revell , Paul Davis , Thomas Gleixner , LKML , mark_h_johnson@raytheon.com, Bill Huey , Adam Heath , Michal Schmidt , Fernando Pablo Lopez-Lezcano , Karsten Wiese , jackit-devel , Rui Nuno Capela , "K.R. Foley" Subject: Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4] Message-ID: <20041101140630.GA20448@elte.hu> References: <20041031120721.GA19450@elte.hu> <20041031124828.GA22008@elte.hu> <1099227269.1459.45.camel@krustophenia.net> <20041031131318.GA23437@elte.hu> <20041031134016.GA24645@elte.hu> <20041031162059.1a3dd9eb@mango.fruits.de> <20041031165913.2d0ad21e@mango.fruits.de> <20041031200621.212ee044@mango.fruits.de> <20041101134235.GA18009@elte.hu> <20041101135358.GA19718@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041101135358.GA19718@elte.hu> 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 Content-Length: 1139 Lines: 29 * Ingo Molnar wrote: > > removing the poll() lines doesnt seem to impact the quality of the > > data, but i still see roughly 50 usecs added to the 'real' latency > > that i see in traces. > > this i think is related to what Thomas observed, that there's a new > irqs-off critical section somewhere. (it's in the new priority > handling code i think.) ah, found it. Only RT tasks were supposed to get special priority handling, while in fact all tasks got it - so when Thomas ran hackbench (Thomas, you did, right?) it created an O(nr_hackbench) overhead within the mutex code ... I've uploaded -V0.6.5 to the usual place: http://redhat.com/~mingo/realtime-preempt/ Thomas, can you confirm that this kernel fixes the irqs-off latencies? (the priority loop indeed was done with irqs turned off.) i'm not sure this fix is related to the deadlocks reported though. 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/