From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261895AbVFLGfz (ORCPT ); Sun, 12 Jun 2005 02:35:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261889AbVFLGfy (ORCPT ); Sun, 12 Jun 2005 02:35:54 -0400 Received: from mx2.elte.hu ([157.181.151.9]:31170 "EHLO mx2.elte.hu") by vger.kernel.org with ESMTP id S261901AbVFLGfP (ORCPT ); Sun, 12 Jun 2005 02:35:15 -0400 Date: Sun, 12 Jun 2005 08:11:08 +0200 From: Ingo Molnar To: Karim Yaghmour Cc: Kristian Benoit , linux-kernel@vger.kernel.org, paulmck@us.ibm.com, bhuey@lnxw.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 ADEOS: the numbers, part 1 Message-ID: <20050612061108.GA4554@elte.hu> References: <42AA6A6B.5040907@opersys.com> <20050611191448.GA24152@elte.hu> <42AB662B.4010104@opersys.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42AB662B.4010104@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, 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: > > how were interrupt response times measured, precisely? What did the > > target (measured) system have to do to respond to an interrupt? Did you > > use the RTC to measure IRQ latencies? > > The logger used two TSC values. One prior to shooting the interrupt to > the target, and one when receiving the response. Responding to an > interrupt meant that a driver was hooked to the target's parallel port > interrupt and simply acted by toggling an output pin on the parallel > port, which in turn was hooked onto the logger's parallel port in a > similar fashion. We'll post the code for all components (both logger > and target) for everyone to review. There's no validity in any tests > if others can't analyze/criticize/ duplicate. ok, this method should work fine. I suspect you increased the parport IRQ's priority to the maximum on the PREEMPT_RT kernel, correct? Was there any userspace thread on the target system (receiving the parport request and sending the reply), or was it all done in a kernelspace parport driver? Ingo