From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261979AbVFVUbr (ORCPT ); Wed, 22 Jun 2005 16:31:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262109AbVFVU3g (ORCPT ); Wed, 22 Jun 2005 16:29:36 -0400 Received: from opersys.com ([64.40.108.71]:55311 "EHLO www.opersys.com") by vger.kernel.org with ESMTP id S261979AbVFVU27 (ORCPT ); Wed, 22 Jun 2005 16:28:59 -0400 Message-ID: <42B9CC98.1040402@opersys.com> Date: Wed, 22 Jun 2005 16:39:52 -0400 From: Karim Yaghmour Reply-To: karim@opersys.com Organization: Opersys inc. User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.2) Gecko/20040805 Netscape/7.2 X-Accept-Language: en-us, en, fr, fr-be, fr-ca, fr-fr MIME-Version: 1.0 To: Ingo Molnar 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 References: <1119287612.6863.1.camel@localhost> <20050620183115.GA27028@nietzsche.lynx.com> <42B98B20.7020304@opersys.com> <20050622192927.GA13817@nietzsche.lynx.com> <20050622200554.GA16119@elte.hu> In-Reply-To: <20050622200554.GA16119@elte.hu> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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: Measurements | Vanilla | preemp_rt | ipipe ---------------+-------------+----------------+------------- fork | 95us | 157us (+65%) | 97us (+2%) open/close | 1.4us | 2.1us (+50%) | 1.4us (~) execve | 355us | 452us (+27%) | 365us (+3%) select 500fd | 12.7us | 27.7us (+118%) | 12.7us (~) mmap | 660us | 2886us (+337%) | 673us (+2%) ... | ... | ... | ... Here's a under ping flood conditions: Measurements | Vanilla | preemp_rt | ipipe ---------------+-------------+----------------+------------- fork | 112us | 223us (+99%) | 121us (+8%) open/close | 1.7us | 3.0us (+76%) | 1.8us (+6%) execve | 421us | 652us (+55%) | 467us (+11%) select 500fd | 14.6us | 38.1us (+161%) | 15.5us (+6%) mmap | 760us | 3936us (+418%) | 819us (+8%) ... | ... | ... | ... etc. it's like this accross the board. Unless that fix you mention above takes care of these, there's something seriously wrong going on here. Are there existing LMbench results posted of PREEMPT_RT which one can go back to for comparison? Karim -- Author, Speaker, Developer, Consultant Pushing Embedded and Real-Time Linux Systems Beyond the Limits http://www.opersys.com || karim@opersys.com || 1-866-677-4546