From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nivedita Singhvi Subject: Re: PREEMPT_RT patch vs RTAI/Xenomai Date: Wed, 12 May 2010 18:27:05 -0700 Message-ID: <4BEB5569.3040008@us.ibm.com> References: <1273680443.27703.33.camel@gandalf.stny.rr.com> <4BEAFB7E.90304@steinhoff.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: rostedt@goodmis.org, Asier Tamayo , linux-rt-users@vger.kernel.org To: Armin Steinhoff Return-path: Received: from e36.co.us.ibm.com ([32.97.110.154]:34001 "EHLO e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757881Ab0EMB1G (ORCPT ); Wed, 12 May 2010 21:27:06 -0400 Received: from d03relay03.boulder.ibm.com (d03relay03.boulder.ibm.com [9.17.195.228]) by e36.co.us.ibm.com (8.14.3/8.13.1) with ESMTP id o4D1Nwqa006402 for ; Wed, 12 May 2010 19:23:58 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay03.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o4D1R659137714 for ; Wed, 12 May 2010 19:27:06 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id o4D1R5XZ020348 for ; Wed, 12 May 2010 19:27:06 -0600 In-Reply-To: <4BEAFB7E.90304@steinhoff.de> Sender: linux-rt-users-owner@vger.kernel.org List-ID: 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 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? thanks, Nivedita