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 10:01:12 +0200 Message-ID: <4BEBB1C8.90606@steinhoff.de> References: <1273680443.27703.33.camel@gandalf.stny.rr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; 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 ([212.227.126.186]:53764 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754683Ab0EMIuO (ORCPT ); Thu, 13 May 2010 04:50:14 -0400 In-Reply-To: <1273680443.27703.33.camel@gandalf.stny.rr.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: Steven Rostedt wrote: > On Tue, 2010-05-11 at 17:30 +0200, Asier Tamayo wrote: > >> Hello Nivedita, >> >> Thanks for your answer. >> >> >>> What are your criteria? Do you care about anything other >>> than performance (availability, upgrades, cost, support, >>> compatibility, tools, ...)? >>> >>> (...) you're best off testing the solutions that you can >>> get hold of with your own workload, in your own environment. >>> >>> >> Performance is a must. Besides, costs and tools are very important. >> Support is also important, but I guess I'd find some good support for >> any of the solutions. >> >> My new CPU has an Intel Atom N270 @1.6 GHz processor. At the moment >> (during the porting it might be optimized), I have 5 drivers requering >> hard real-time (no loop can be skipped) and being called every 2 to 10 >> ms. In fact, at the beginning I was using 1 ms, but I had some >> problems with the hard real-time and changed the timing to 2 ms. I do >> not consider using a legacy OS emulation. >> > > 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 !! 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. --Armin http://www.steinhoff-automation.com