From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Luis Claudio R. Goncalves" Subject: Re: High 50us+ latencies in the process signal handling path Date: Thu, 18 Oct 2007 11:36:18 -0400 Message-ID: <20071018153618.GI12471@unix.sh> References: <20071018124827.GA22282@in.ibm.com> <20071018.055242.115933276.davem@davemloft.net> <20071018132614.GB22282@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Ankita Garg , David Miller , linux-rt-users@vger.kernel.org, rostedt@goodmis.org, ghaskins@novell.com, mingo@elte.hu, dino@in.ibm.com, dvhltc@ Return-path: Received: from tucuriba.hst.terra.com.br ([200.176.10.214]:46116 "EHLO tucuriba.hst.terra.com.br" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751706AbXJRNoD (ORCPT ); Thu, 18 Oct 2007 09:44:03 -0400 Received: from sr06-06.mta.terra.com.br (sr06-06.mta.terra.com.br [200.154.152.75]) by tucuriba.hst.terra.com.br (Postfix) with ESMTP id F0EA427D369 for ; Thu, 18 Oct 2007 11:40:25 -0200 (BRST) Content-Disposition: inline In-Reply-To: <20071018132614.GB22282@in.ibm.com> Sender: linux-rt-users-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org Ankita, On Thu, Oct 18, 2007 at 06:56:14PM +0530, Ankita Garg wrote: | Hi David, | | On Thu, Oct 18, 2007 at 05:52:42AM -0700, David Miller wrote: | > From: ankita@in.ibm.com (Ankita Garg) | > Date: Thu, 18 Oct 2007 18:18:27 +0530 | > | > > Any thoughts on where in the code could these large latencies be | > > attributed to? | > | > If the max latency is usually the first one, it's could be the page | > fault the signal handler is taking the first time it is executed. | | Thanks for looking into this. Attaching the entire log from the testrun. | It indicates that in each run of the 10000 iterations, there are about 100+ | failures, with large iterations. Also, on intrumenting the testcode to | find out the iterations which see large latencies, I see that as the | number of iterations increase, the latencies increase. You might wanna check signaltest: git clone git://git.kernel.org/pub/scm/linux/kernel/git/tglx/rt-tests.git rt-tests Regards, Luis -- [ Luis Claudio R. Goncalves Bass - Gospel - RT ] [ Fingerprint: 4FDD B8C4 3C59 34BD 8BE9 2696 7203 D980 A448 C8F8 ]