From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759409AbXGYOFx (ORCPT ); Wed, 25 Jul 2007 10:05:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753481AbXGYOFo (ORCPT ); Wed, 25 Jul 2007 10:05:44 -0400 Received: from smtp4-g19.free.fr ([212.27.42.30]:53806 "EHLO smtp4-g19.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753086AbXGYOFn (ORCPT ); Wed, 25 Jul 2007 10:05:43 -0400 Message-ID: <46A758B5.9070602@free.fr> Date: Wed, 25 Jul 2007 16:05:41 +0200 From: John Sigler User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.8) Gecko/20061108 SeaMonkey/1.0.6 MIME-Version: 1.0 To: Ingo Molnar CC: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Pin-pointing the root of unusual application latencies References: <469600F7.3060603@free.fr> <20070723095357.GA886@elte.hu> <46A4B7C2.1070304@free.fr> <20070723160442.GA7995@elte.hu> <46A5B8E3.4060004@free.fr> <46A74A58.1070704@free.fr> <20070725130536.GA12334@elte.hu> <46A74E05.50504@free.fr> <20070725133835.GA17616@elte.hu> In-Reply-To: <20070725133835.GA17616@elte.hu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: > John Sigler wrote: > >> Ingo Molnar wrote: >> >>> does your test-app have higher priority than softirq--4 ? >> >> PID 4 is [softirq-timer/0] and has priority 50 in SCHED_FIFO. My >> process has priority 80 in SCHED_RR. It is waiting for IRQ10. >> >> My user-space app has higher priority than everything except PID 2 >> which is [posix_cpu_timer] > > well what priority does the IRQ 10 kernel thread have? It should be prio > 80 too if it's in your critical path. Is there some form of priority inheritance? Does the IRQ handler get a priority boost if a high priority task is waiting for it? I didn't dare mess with the default kernel thread priorities. # ps -eo pid,class,rtprio,ni,pri,stat,comm PID CLS RTPRIO NI PRI STAT COMMAND 1 TS - 0 24 Ss init 2 FF 99 - 139 S posix_cpu_timer 3 FF 50 - 90 S softirq-high/0 4 FF 50 - 90 S softirq-timer/0 5 FF 50 - 90 S softirq-net-tx/ 6 FF 50 - 90 S softirq-net-rx/ 7 FF 50 - 90 S softirq-block/0 8 FF 50 - 90 S softirq-tasklet 9 FF 50 - 90 S softirq-sched/0 10 FF 50 - 90 S softirq-hrtimer 11 FF 50 - 90 S softirq-rcu/0 12 TS - -10 34 S< desched/0 13 FF 1 - 41 S< events/0 14 TS - -5 19 S< khelper 15 TS - -5 19 S< kthread 34 TS - -5 29 S< kblockd/0 35 TS - -5 19 S< kacpid 36 FF 50 - 90 S< IRQ-7 82 TS - -5 29 S< kseriod 101 TS - 0 16 S pdflush 102 TS - 0 24 S pdflush 103 TS - -5 21 S< kswapd0 104 TS - -5 29 S< flush_filesd/0 105 TS - -5 21 S< aio/0 704 FF 50 - 90 S< IRQ-14 720 FF 50 - 90 S< IRQ-12 721 FF 50 - 90 S< IRQ-1 848 FF 50 - 90 S< IRQ-11 913 FF 50 - 90 S< IRQ-10 922 TS - 0 21 Ss sshd 925 TS - 0 24 Ss+ agetty 926 TS - 0 21 Ss+ agetty 931 TS - 0 24 Rs sshd 933 TS - 0 24 Rs bash # cat /proc/interrupts CPU0 0: 37 XT-PIC-XT timer 1: 2 XT-PIC-XT i8042 2: 0 XT-PIC-XT cascade 7: 0 XT-PIC-XT acpi 10: 175 XT-PIC-XT eth2, Dta1xx 11: 1129 XT-PIC-XT eth0 12: 4 XT-PIC-XT eth1 14: 21482 XT-PIC-XT ide0 NMI: 0 LOC: 161632 ERR: 0 MIS: 0 IRQ 10 is shared between a NIC and an I/O board. For eth2, the kernel said: ACPI: PCI Interrupt 0000:00:0a.0[A] -> Link [LNKC] -> GSI 10 (level, low) -> IRQ 10 For Dta1xx, the kernel said: ACPI: PCI Interrupt 0000:02:0e.0[A] -> Link [LNKC] -> GSI 10 (level, low) -> IRQ 10 Is it possible to avoid the two boards sharing IRQ 10? Regards.