Date: Sun, 31 Oct 2004 15:28:06 +0100
From: Florian Schmidt <mista.tapas@gmx.net>
To: Ingo Molnar <mingo@elte.hu>
Cc: Lee Revell <rlrevell@joe-job.com>, Paul Davis <paul@linuxaudiosystems.com>,
       Thomas Gleixner <tglx@linutronix.de>,
       LKML <linux-kernel@vger.kernel.org>, mark_h_johnson@raytheon.com,
       Bill Huey <bhuey@lnxw.com>, Adam Heath <doogie@debian.org>,
       Michal Schmidt <xschmi00@stud.feec.vutbr.cz>,
       Fernando Pablo Lopez-Lezcano <nando@ccrma.stanford.edu>,
       Karsten Wiese <annabellesgarden@yahoo.de>,
       jackit-devel <jackit-devel@lists.sourceforge.net>,
       Rui Nuno Capela <rncbc@rncbc.org>
Subject: Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4]
Message-ID: <20041031152806.058a19da@mango.fruits.de>
In-Reply-To: <20041031132237.GB23437@elte.hu>
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On Sun, 31 Oct 2004 14:22:37 +0100
Ingo Molnar <mingo@elte.hu> wrote:


> cool! May i have a feature request :-) It would be quite useful to have
> an option to see the jitter output in percentage and in microseconds as
> well. I.e. an option to have such a format:
> 
>  late wakeup: +151.3 usecs (14.6%) jitter.

yep, will do so ater trying the 0.6.1 kernel.

> cycles are too large to be human readable, and absolute values are
> harder to read when HZ is not 1024. So to get a 'quick feel' of the
> delays in a system the above line would be the most informative (for me
> that is). Also, the percentage can go back to %.1f i think, instead of
> %.5f or so - it's good to have a decimal point in the percentage but one
> number after it is more than enough.) The more compact the output, the
> fewer useless info, the quicker the human brain can read it. (Obviously
> to generate a nice graph out of it needs a different format.)

well, to generate graphs out of the data one can choose to write the raw
cycle counts into a "history file". Then one can process this raw data to
hearts content. i will update the output routines to truncate the percentage
to %.1f [or the c++ equivalent :)]

> 
> > Here's a typical run (still on V0.5.16, will try V0.6 now):
> 
> please try -V0.6.1, -V0.6 had a pretty stupid bug that could trigger
> frequently.
> 
> > threshold violations: 20
> > max jitter:           58.1228%
> 
> here it would also be useful to have the 'max jitter' in usecs. I.e. in
> the above case it was somewhere around ~570 usecs.

ack.

flo
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