Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265570AbTFRWQN (ORCPT ); Wed, 18 Jun 2003 18:16:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265566AbTFRWQN (ORCPT ); Wed, 18 Jun 2003 18:16:13 -0400 Received: from gateway-1237.mvista.com ([12.44.186.158]:54258 "EHLO av.mvista.com") by vger.kernel.org with ESMTP id S265570AbTFRWPb (ORCPT ); Wed, 18 Jun 2003 18:15:31 -0400 Message-ID: <3EF0E7AC.60007@mvista.com> Date: Wed, 18 Jun 2003 15:29:00 -0700 From: george anzinger User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2) Gecko/20021202 X-Accept-Language: en-us, en MIME-Version: 1.0 To: joe.korty@ccur.com CC: lkml , Ingo Molnar Subject: Re: O(1) scheduler seems to lock up on sched_FIFO and sched_RR tasks References: <3EF0979C.8060603@mvista.com> <20030618193053.GA15576@tsunami.ccur.com> In-Reply-To: <20030618193053.GA15576@tsunami.ccur.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1728 Lines: 49 Joe Korty wrote: > On Wed, Jun 18, 2003 at 09:47:24AM -0700, george anzinger wrote: > >>It seems that once a SCHED_FIFO or SCHED_RR tasks gets control it does >>not yield to other tasks of higher priority. >> >>Attached is a test program (busyloop) that just loops doing >>gettimeofday() for the requested time and a little utility (rt) to run >>programs at real time priorities. >> >>Here is an annotated example of the problem: >> >>First, become root then: >> >>>rt 90 bash <-- run bash at priority 90 SCHED_RR >>>rt -f 30 busyloop 10 & <-- busyloop 10 at priority 30 SCHED_FIFO >> >>At this point the bash at priority 90 should be available, but is not. >> When the 10 second busyloop completes, bash returns. > > > > Hi George, > When I boost the priority of each of the per-cpu 'events/%d' daemon to > 96, the problem goes away. Seems like your saying that the events workqueues are involved in the scheduler in some ugly way. Certainly not what your average rt programmer would expect :( What is going on here? > > Joe > - > 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/ > -- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml - 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/