Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261858AbUKPWOy (ORCPT ); Tue, 16 Nov 2004 17:14:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261852AbUKPWNc (ORCPT ); Tue, 16 Nov 2004 17:13:32 -0500 Received: from mx2.elte.hu ([157.181.151.9]:17536 "EHLO mx2.elte.hu") by vger.kernel.org with ESMTP id S261859AbUKPWKt (ORCPT ); Tue, 16 Nov 2004 17:10:49 -0500 Date: Wed, 17 Nov 2004 00:11:45 +0100 From: Ingo Molnar To: Florian Schmidt Cc: "K.R. Foley" , Mark_H_Johnson@raytheon.com, linux-kernel@vger.kernel.org, Lee Revell , Rui Nuno Capela , Bill Huey , Adam Heath , Thomas Gleixner , Michal Schmidt , Fernando Pablo Lopez-Lezcano , Karsten Wiese , Gunther Persoons , emann@mrv.com, Shane Shrybman , Amit Shah , Stefan Schweizer Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm1-V0.7.27-3 Message-ID: <20041116231145.GC31529@elte.hu> References: <20041116184315.GA5492@elte.hu> <419A5A53.6050100@cybsft.com> <20041116212401.GA16845@elte.hu> <20041116222039.662f41ac@mango.fruits.de> <20041116223243.43feddf4@mango.fruits.de> <20041116224257.GB27550@elte.hu> <20041116230443.452497b9@mango.fruits.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041116230443.452497b9@mango.fruits.de> 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: 1671 Lines: 41 * Florian Schmidt wrote: > hmm, the output doens't look so much different (or am i just blind?). > maybe i need to do make clean before building with this patch applied? the trace is fine, note the extra 0x08000000: > 5 88010003 0.000ms (+0.000ms): try_to_wake_up (wake_up_process) > 5 88010003 0.000ms (+0.000ms): (0) ((1)) > 5 88010002 0.000ms (+0.000ms): preempt_schedule (try_to_wake_up) > 5 88010002 0.000ms (+0.000ms): wake_up_process (redirect_hardirq) ^--- this one > 5 88010001 0.000ms (+0.000ms): preempt_schedule (__do_IRQ) > 5 88010001 0.000ms (+0.000ms): irq_exit (do_IRQ) > 5 88000002 0.000ms (+0.000ms): do_softirq (irq_exit) > 5 88000002 0.001ms (+0.990ms): __do_softirq (do_softirq) > 5 08000000 0.991ms (+0.000ms): preempt_schedule (_mmx_memcpy) > 5 98000000 0.991ms (+0.000ms): __schedule (preempt_schedule) it was zero before - indeed hard to notice optically :-| found the reason for this latency meanwhile: it's kernel_fpu_begin() and kernel_fpu_end() disabling/enabling preemption. (these are used by the mmx memcpy's) i've uploaded the -11 patch with a preliminary fix: http://redhat.com/~mingo/realtime-preempt/ which turns off the FPU-based ops if PREEMPT_RT is specified. The speed difference should be small but the latency difference is large ... could you try -11, do you still see these large latencies? 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/