From mboxrd@z Thu Jan 1 00:00:00 1970 From: Holger Steinhaus Subject: Re: realtime scheduling Date: Mon, 08 Aug 2005 23:11:03 +0200 Message-ID: <42F7CA67.8000901@gmx.de> References: <42F77510.5070501@gmx.de> <42F79359.8050900@cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <42F79359.8050900@cam.ac.uk> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org >The default compile of the sedf scheduler is not optimised for latency >(but the standard setting might work well...). >You can do a couple of things: > -set the period of dom0 to roughly your latency (better half of it) >and scale your slice accordingly > (e.g. 2ms period, 0.3ms slice...) > > Ok, done. I installed a fresh devel version of Xen (from Aug 7), including kernel 2.6.12.3 and SEDF scheduling (in my original post: Xen 2.0.7, kernel 2.6.11.12, original scheduler). The major change: now the buffer problems even occur without any user domain. I tried to play around with the period/slice parameters, and found some values that really boost the problems. As the HFC driver generates 8000 interupts per second (I assume for timing purposes), the desired period of 62500 ns is not possible on my machine. I think, I'll take a closer look on the driver first... > -or edit xen/common/schedule_sedf.c and change > #define UNBLOCK UNBLOCK_EXTRA_SUPPORT > to > #define UNBLOCK UNBLOCK_ATROPOS > and then set the appropriate latancy value in xm sedf (this does >exactly the same thing internaly > > Makes no recognizable difference, in my opinion. Thanks, Holger