From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262301AbVGGAXK (ORCPT ); Wed, 6 Jul 2005 20:23:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262348AbVGFUBC (ORCPT ); Wed, 6 Jul 2005 16:01:02 -0400 Received: from mail.metronet.co.uk ([213.162.97.75]:12735 "EHLO mail.metronet.co.uk") by vger.kernel.org with ESMTP id S262334AbVGFQ4Y (ORCPT ); Wed, 6 Jul 2005 12:56:24 -0400 From: Alistair John Strachan To: Ingo Molnar Subject: Re: Realtime Preemption, 2.6.12, Beginners Guide? Date: Wed, 6 Jul 2005 17:56:20 +0100 User-Agent: KMail/1.8.1 Cc: linux-kernel@vger.kernel.org References: <200507061257.36738.s0348365@sms.ed.ac.uk> <20050706162457.GA24728@elte.hu> <200507061737.18322.s0348365@sms.ed.ac.uk> In-Reply-To: <200507061737.18322.s0348365@sms.ed.ac.uk> MIME-Version: 1.0 Content-Type: Multipart/Mixed; boundary="Boundary-00=_00AzC1Ead3/f7x9" Message-Id: <200507061756.20861.s0348365@sms.ed.ac.uk> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --Boundary-00=_00AzC1Ead3/f7x9 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline On Wednesday 06 Jul 2005 17:37, Alistair John Strachan wrote: [big snip] > > > > could you try the patch below (or the -51-05 patch that i just > > uploaded), does it fix this latency? > > > > Ingo > > I'm beginning to understand the issue, and I see why you think the proposed > patch fixes it. I'll compile and boot V0.7.51-05 now. Indeed, this seems to have fixed it. ( softirq-timer/0-3 |#0): new 8 us maximum-latency wakeup. ( softirq-timer/0-3 |#0): new 9 us maximum-latency wakeup. ( softirq-timer/0-3 |#0): new 9 us maximum-latency wakeup. ( softirq-timer/0-3 |#0): new 9 us maximum-latency wakeup. ( softirq-timer/0-3 |#0): new 10 us maximum-latency wakeup. ( softirq-timer/0-3 |#0): new 14 us maximum-latency wakeup. Find attached another trace (only 33us this time). -- Cheers, Alistair. personal: alistair()devzero!co!uk university: s0348365()sms!ed!ac!uk student: CS/CSim Undergraduate contact: 1F2 55 South Clerk Street, Edinburgh. EH8 9PP. --Boundary-00=_00AzC1Ead3/f7x9 Content-Type: text/plain; charset="iso-8859-1"; name="trace3" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="trace3" preemption latency trace v1.1.4 on 2.6.12-RT-V0.7.51-05 -------------------------------------------------------------------- latency: 38 us, #27/27, CPU#0 | (M:rt VP:0, KP:1, SP:1 HP:1 #P:1) ----------------- | task: softirq-timer/0-3 (uid:0 nice:-10 policy:0 rt_prio:0) ----------------- _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / <...>-3485 0dnh3 0us!: <6f6f726b> (<616d6974>) <...>-3485 0dnh3 1us : __trace_start_sched_wakeup (try_to_wake_up) <...>-3485 0dnh3 1us : __trace_start_sched_wakeup (69 0) <...>-3485 0dnh2 2us : try_to_wake_up (69 76) <...>-3485 0dnh1 2us : preempt_schedule (try_to_wake_up) <...>-3485 0dnh1 3us : wake_up_process (trigger_softirqs) <...>-3485 0dnh1 3us : local_irq_restore (do_softirq) <...>-3485 0Dnh1 4us+: preempt_schedule (do_softirq) <...>-3485 0Dnh. 7us : __schedule (work_resched) <...>-3485 0Dnh. 8us : profile_hit (__schedule) <...>-3485 0Dnh1 8us+: sched_clock (__schedule) <...>-3485 0Dnh2 12us : dequeue_task (__schedule) <...>-3485 0Dnh2 13us : recalc_task_prio (__schedule) <...>-3485 0Dnh2 13us : effective_prio (recalc_task_prio) <...>-3485 0Dnh2 13us : enqueue_task (__schedule) <...>-3485 0Dnh2 14us+: trace_array (__schedule) <...>-3485 0Dnh2 18us : trace_array (69 6e) <...>-3485 0Dnh2 18us : trace_array <<...>-3485> (76 78) <...>-3485 0Dnh2 20us+: trace_array (__schedule) softirq--3 0Dnh2 28us+: __switch_to (__schedule) softirq--3 0Dnh2 31us : __schedule <<...>-3485> (76 69) softirq--3 0Dnh2 31us : finish_task_switch (__schedule) softirq--3 0Dnh1 32us : trace_stop_sched_switched (finish_task_switch) softirq--3 0Dnh2 33us+: trace_stop_sched_switched (69 0) softirq--3 0Dnh2 35us : trace_stop_sched_switched (finish_task_switch) vim:ft=help --Boundary-00=_00AzC1Ead3/f7x9--