Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261465AbVDDXUD (ORCPT ); Mon, 4 Apr 2005 19:20:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261494AbVDDXTM (ORCPT ); Mon, 4 Apr 2005 19:19:12 -0400 Received: from ms-smtp-01.nyroc.rr.com ([24.24.2.55]:19847 "EHLO ms-smtp-01.nyroc.rr.com") by vger.kernel.org with ESMTP id S261477AbVDDXRK (ORCPT ); Mon, 4 Apr 2005 19:17:10 -0400 Subject: Re: scheduler/SCHED_FIFO behaviour From: Steven Rostedt To: Arun Srinivas Cc: juhl-lkml@dif.dk, LKML In-Reply-To: References: Content-Type: text/plain Organization: Kihon Technologies Date: Mon, 04 Apr 2005 19:17:04 -0400 Message-Id: <1112656624.5147.34.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.0.4 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1656 Lines: 50 On Tue, 2005-04-05 at 04:36 +0530, Arun Srinivas wrote: > I am scheduling 2 SCHED_FIFO processes and set them affinity( process A runs > on processor 1 and process B runs on processor 2), on a HT processor.(I did > this cause I wanted to run them together).Now, in schedule() I measure the > timedifference between when they are scheduled. I found that when I > introduce these 2 processes as SCHED_FIFO they are > > 1)scheduled only once and run till completion ( they running time is around > 2 mins.) If they are the highest priority task, and running as FIFO this is the proper behavior. > 2)entire system appears frozen....no mouse/key presses detected until the > processes exit. > If X is not at a higher priority than the test you are running, it will never get a chance to run. > >From what I observed does it mean that even the OS / interrupt handler does > not occur during the entire period of time these real time processes run?? > (as I said the processes run in minutes). The interrupts do get processed. Now the bottom halves and tasklets may be starved if they are set at a lower priority than your test (ie. the ksoftirqd thread). But most likely they are processed too. > How can I verify that? > #!/bin/sh cat /proc/interrupts run_test cat /proc/interrupts If the run_test takes 2 minutes, you should see a large difference in the two outputs. -- Steve > Thanks > Arun - 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/