From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262441AbVFVW26 (ORCPT ); Wed, 22 Jun 2005 18:28:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261175AbVFVW26 (ORCPT ); Wed, 22 Jun 2005 18:28:58 -0400 Received: from mx1.elte.hu ([157.181.1.137]:37329 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S262441AbVFVWFK (ORCPT ); Wed, 22 Jun 2005 18:05:10 -0400 Date: Thu, 23 Jun 2005 00:04:28 +0200 From: Ingo Molnar To: Karim Yaghmour Cc: Bill Huey , Kristian Benoit , linux-kernel@vger.kernel.org, paulmck@us.ibm.com, andrea@suse.de, tglx@linutronix.de, pmarques@grupopie.com, bruce@andrew.cmu.edu, nickpiggin@yahoo.com.au, ak@muc.de, sdietrich@mvista.com, dwalker@mvista.com, hch@infradead.org, akpm@osdl.org, rpm@xenomai.org Subject: Re: PREEMPT_RT vs I-PIPE: the numbers, part 2 Message-ID: <20050622220428.GA28906@elte.hu> References: <1119287612.6863.1.camel@localhost> <20050620183115.GA27028@nietzsche.lynx.com> <42B98B20.7020304@opersys.com> <20050622192927.GA13817@nietzsche.lynx.com> <20050622200554.GA16119@elte.hu> <42B9CC98.1040402@opersys.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42B9CC98.1040402@opersys.com> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Karim Yaghmour wrote: > Ingo Molnar wrote: > > the UDP-over-localhost latency was a softirq processing bug that is > > fixed in current PREEMPT_RT patches. (real over-the-network latency was > > never impacted, that's why it wasnt noticed before.) > > That's good to hear, but here are some random stats from the idle run: please retest using recent (i.e. today's) -RT kernels. There were a whole bunch of fixes that could affect these numbers. (But i'm sure you know very well that you cannot expect a fully-preemptible kernel to have zero runtime cost. In that sense, if you want to be fair, you should compare it to the SMP kernel, as total preemptability is a similar technological feat and has very similar parallelism constraints.) Ingo