From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Grandegger Subject: Re: [SocketCan] Problem of accuracy Date: Thu, 12 Jul 2012 00:19:40 +0200 Message-ID: <4FFDFBFC.5030803@grandegger.com> References: <201207091519.04235.pisa@cmp.felk.cvut.cz> <20120709144042.GA2671@vandijck-laurijssen.be> <23562188.349Ls0e8RT@ws-stein> <4FFB43FF.8060305@grandegger.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from ngcobalt02.manitu.net ([217.11.48.102]:39123 "EHLO ngcobalt02.manitu.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932203Ab2GKWTo (ORCPT ); Wed, 11 Jul 2012 18:19:44 -0400 In-Reply-To: Sender: linux-can-owner@vger.kernel.org List-ID: To: Mohamed HAMZAOUI Cc: Alexander Stein , Kurt Van Dijck , Pavel Pisa , Linux-CAN On 07/11/2012 12:11 AM, Mohamed HAMZAOUI wrote: > Hi, > > i run cyclictest command like your description with system load at 90% > (i use stress command stress -t 3600 -c 1 --io 2 --vm-bytes 256M) and > i have : > Min 0 Avg 158 Max 334 Please create almost 100% load on all CPUs and run the test for a while (at least an hour). > then i create a program with timer (set to zero for increasing to > maximum CPU load) who call periodically an empty function. This > program have a priority 99 set using sched_setscheduler(0, SCHED_RR, > &p); > when i call this program cyclictest freeze and display me after a > moment a very bigger value in Max, then i concluded that the OS > schedule correctly the process according to the priority order. The programm does block cyclictest becase it does have a higher priority. That's pretty normal. Wolfgang