From mboxrd@z Thu Jan 1 00:00:00 1970 From: Armin Steinhoff Subject: Re: PREEMPT_RT patch vs RTAI/Xenomai Date: Thu, 13 May 2010 10:07:57 +0200 Message-ID: <4BEBB35D.6080004@steinhoff.de> References: <1273680443.27703.33.camel@gandalf.stny.rr.com> <4BEAFB7E.90304@steinhoff.de> <4BEB5569.3040008@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-rt-users@vger.kernel.org To: unlisted-recipients:; (no To-header on input) Return-path: Received: from moutng.kundenserver.de ([212.227.17.10]:50000 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751585Ab0EMI4z (ORCPT ); Thu, 13 May 2010 04:56:55 -0400 In-Reply-To: <4BEB5569.3040008@us.ibm.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: Nivedita Singhvi wrote: > Armin Steinhoff wrote: > >>> If tuned properly, PREEMPT_RT can easily handle 1ms requirements. On a >>> standard x86 CPU (we support others than x86) our goal is never to be >>> >> >> I did a test with user space based CAN driver. >> Already the standard distribution of SUSE 11.2 (non RT) was able to >> handle 1000 frames per seconds sent by a QNX6 machine !! > > If your requirements are "never to exceed" a certain latency, > I highly recommend you run tests for long-durations, rather > than a short period. A 10-min or even a 1 hour run will not > give you a full idea as a 24-72 hour run will. The test was running for more than 12 hours. That's the typical test before the software will be released. > >> The PREEMPT_RT version of SUSE 11.2 is much, much faster :-) >>> over 100us in reaction time. >>> >> >> The latency test of PREEMPT_RT shows a latency of ~10us for a >> dual-core box at 1.8GHz. > > Are you using cyclictest? And how long did you run it for? Several hours ... --Armin PS: my initial post has been posted again because of internet problems, sorry.