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Date: Thu, 9 Dec 2004 18:31:36 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Mark_H_Johnson@raytheon.com
Cc: Amit Shah <amit.shah@codito.com>,
       Karsten Wiese <annabellesgarden@yahoo.de>, Bill Huey <bhuey@lnxw.com>,
       Adam Heath <doogie@debian.org>, emann@mrv.com,
       Gunther Persoons <gunther_persoons@spymac.com>,
       "K.R. Foley" <kr@cybsft.com>, linux-kernel@vger.kernel.org,
       Florian Schmidt <mista.tapas@gmx.net>,
       Fernando Pablo Lopez-Lezcano <nando@ccrma.Stanford.EDU>,
       Lee Revell <rlrevell@joe-job.com>, Rui Nuno Capela <rncbc@rncbc.org>,
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       Thomas Gleixner <tglx@linutronix.de>,
       Michal Schmidt <xschmi00@stud.feec.vutbr.cz>
Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.32-6
Message-ID: <20041209173136.GE7975@elte.hu>
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* Mark_H_Johnson@raytheon.com <Mark_H_Johnson@raytheon.com> wrote:

> >also, i'd like to take a look at latency traces, if you have them for
> >this run.
> 
> I could if I had any. The _RT run had NO latency traces > 250 usec
> (the limit I had set for the test). The equivalent _PK run had 37 of
> those traces. I can rerun the test with a smaller limit to get some if
> it is really important. My build of -12 is almost done and we can see
> what kind of repeatability / results from the all_cpus trace shows.

/me is puzzled.

so all the CPU-loop delays within the -RT kernel are below 250 usecs? I
guess i dont understand what this means then:

| The max CPU latencies in RT are worse than PK as well. The values for
| RT range from 3.00 msec to 5.43 msec and on PK range from 1.45 msec to
| 2.24 msec.

these come from userspace timestamping? So where userspace detects a
delay the kernel tracer doesnt measure any?

	Ingo