From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750737AbWFOWNo (ORCPT ); Thu, 15 Jun 2006 18:13:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750739AbWFOWNo (ORCPT ); Thu, 15 Jun 2006 18:13:44 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:47034 "EHLO e36.co.us.ibm.com") by vger.kernel.org with ESMTP id S1750737AbWFOWNn (ORCPT ); Thu, 15 Jun 2006 18:13:43 -0400 From: Darren Hart Organization: IBM Linux Technology Center To: Mike Kravetz Subject: Re: [RFC PATCH -rt] Priority preemption latency Date: Thu, 15 Jun 2006 15:13:36 -0700 User-Agent: KMail/1.9.1 Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Thomas Gleixner , John Stultz References: <200606091701.55185.dvhltc@us.ibm.com> <200606120838.25200.dvhltc@us.ibm.com> <20060615210658.GA19525@monkey.ibm.com> In-Reply-To: <20060615210658.GA19525@monkey.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200606151513.37670.dvhltc@us.ibm.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 15 June 2006 14:06, Mike Kravetz wrote: > On Mon, Jun 12, 2006 at 08:38:24AM -0700, Darren Hart wrote: > > I started running this version of the patch with prio-preemt in a loop > > over 10 hours ago, and it's still running. This seems to be the right > > fix. > > Unfortunately, this test did eventually fail over in our environment. > John Stultz added the concept of 'interrupter threads' to the testcase. > These high priority RT interrupter threads, occasionally wake up and > run for a short period of time. Since these new threads are higher > priority than any other, they theoretically should not impact the > testcase. This is because the primary purpose of the testcase is to > ensure that lower priority tasks do not run while higher priority tasks > are waiting for a CPU. > > After adding these interrupter threads, the tetscase fails (on a system > here) about 50% of the time. An updated version of prio-preempt.c is > attached. It needs the same headers/makefile/etc as originally provided > by Darren. Thanks for the update Mike! I have incorporated the interrupter threads using a command line argument, -i, they are disabled by default. Grab the latest here: http://linux.dvhart.com/tests/ To run the test on a 4 way machine with interrupter threads enabled, use: $ ./prio-preempt -n 4 -i > > Any help figuring out what is happening here would be appreciated. -- Darren Hart IBM Linux Technology Center Realtime Linux Team Phone: 503 578 3185 T/L: 775 3185