From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Olbrich Subject: Re: jitter bursts Date: Wed, 5 Sep 2007 11:01:47 +0200 Message-ID: <20070905090147.GA32165@pengutronix.de> References: <20070831151727.GT23573@pengutronix.de> <34ac6d890708310855v413383cm2bd725501a685842@mail.gmail.com> <20070905081402.GA30955@pengutronix.de> <34ac6d890709050136v2b061c76pfb149667faa82617@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Robert Schwebel , kiszka@rts.uni-hannover.de To: linux-rt-users@vger.kernel.org Return-path: Received: from metis.extern.pengutronix.de ([83.236.181.26]:33252 "EHLO metis.extern.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756077AbXIEJBt (ORCPT ); Wed, 5 Sep 2007 05:01:49 -0400 Content-Disposition: inline In-Reply-To: <34ac6d890709050136v2b061c76pfb149667faa82617@mail.gmail.com> Sender: linux-rt-users-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org On Wed, Sep 05, 2007 at 02:06:36PM +0530, Girish kathalagiri wrote: > > Unfortunately not but it did get me on the right track. The problem is > > caused by the e100_watchdog function. As far as I can tell e100_watchdog > > is called from a timer queue and therefore runs with the priority of > > that thread. And while I set higher priorities for softirq-net-rx and > > the application I missed the thread for the hardware interrupt of the > > network interface. So whenever a packet arived while e100_watchdog was > > running it got delayed. The periodic pattern is a result of this and > > speed difference of sender and receiver clocks. > > The jitter is now <50us but still with some periodic patterns. So I'll > > need to investigate further. > > > There was some discussion going on this issue on netdev .... > The below link might help you. > http://www.nabble.com/Re%3A-My-vote-against-eepro*-removal-t954330.html#a2532617 Yes that's exactly the issue I've been experiencing. Thanks for the link. michael -- Pengutronix - Linux Solutions for Science and Industry Entwicklungszentrum Nord http://www.pengutronix.de