Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965259AbWEOVta (ORCPT ); Mon, 15 May 2006 17:49:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965263AbWEOVta (ORCPT ); Mon, 15 May 2006 17:49:30 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:30605 "EHLO e6.ny.us.ibm.com") by vger.kernel.org with ESMTP id S965259AbWEOVt3 convert rfc822-to-8bit (ORCPT ); Mon, 15 May 2006 17:49:29 -0400 From: Darren Hart Organization: IBM Linux Technology Center To: =?iso-8859-15?q?S=E9bastien_Dugu=E9?= Subject: Re: rt20 scheduling latency testcase and failure data Date: Mon, 15 May 2006 14:49:20 -0700 User-Agent: KMail/1.9.1 Cc: lkml , Ingo Molnar , Thomas Gleixner , Mike Galbraith , Steven Rostedt , Florian Schmidt References: <200605121924.53917.dvhltc@us.ibm.com> <200605131106.16864.dvhltc@us.ibm.com> <1147692048.3970.21.camel@frecb000686> In-Reply-To: <1147692048.3970.21.camel@frecb000686> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200605151449.21398.dvhltc@us.ibm.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2268 Lines: 64 On Monday 15 May 2006 04:20, S?bastien Dugu? wrote: > On Sat, 2006-05-13 at 11:06 -0700, Darren Hart wrote: > > These tests are running on a 4 way opteron at 2 GHz with 4 GB RAM. I > > have attached the .config and a listing of all the rt tasks running on > > the system (which addresses the questions regarding priority setup, IRQ > > handlers, and softirqs - all default). I am running with the futex > > priority based wakeup patches from Sebastien Duque, but I don't think > > this test excercises those paths. > > Which watchdog are you using here? Have you tried without the > watchdog? Those are the softlockup watchdog threads (kernel/softlockup.c). They run once a second and reports a bug if the watchdog failed to run in 10 seconds. It is difficult to reproduce but at run 126 (1,260,000 iterations) it finally failed. Note that I am only counting runs that completely miss an entire period as a failure for the purposes of this test. I want to knock out the 10+ms latencies before I concern myself too much with the >100us failures :-) -------------------- ITERATION 26 -------------------- ------------------------------- Scheduling Latency ------------------------------- Running 10000 iterations with a period of 5 ms Expected running time: 50 s ITERATION DELAY(US) MAX_DELAY(US) FAILURES --------- --------- ------------- -------- PERIOD MISSED! scheduled delta: 4076 us actual delta: 14892 us latency: 10815 us --------------------------------------- previous start: 18365818 us now: 18366739 us scheduled start: 18360000 us next scheduled start is in the past! Start Latency: 106 us: FAIL Min Latency: 8 us: PASS Avg Latency: 4 us: PASS Max Latency: 10818 us: FAIL Failed Iterations: 1 It's interesting, this 10ms latency seems to be the most common result. I'm going to take a look at ingo's tracing script now, more info a bit later... -- Darren Hart IBM Linux Technology Center Realtime Linux Team - 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/