From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
To: xenomai@xenomai.org
Subject: Re: [Xenomai-help] Strange results with latency test
Date: Thu, 09 Nov 2006 15:04:50 +0100 [thread overview]
Message-ID: <45533582.40808@domain.hid> (raw)
In-Reply-To: <20061109133632.GA4205@domain.hid>
Matthias Fechner wrote:
> Hi,
>
> I tested today Xenomai on my AMD64 (32-bit mode) with the latency
> program from the testsuite and I got for lat min negative values.
>
> Can my computer predict the future? :)
The expiration time of a timer is usually known in advance, so, in that
sense, your computer predicts the future.
>
> How can I interpret these values?
It means that Xenomai anticipates, that is, the timer is programmed
to tick a bit early in order to account for the interrupt and scheduling
latencies. In your case it is a bit too early, you can change this
anticipation time at compilation time with the configuration constant
CONFIG_OPT_TIMING_TIMERLAT and CONFIG_XENO_OPT_TIMING_SCHEDLAT, or
change it at run time by writing a new value in /proc/xenomai/latency.
--
Gilles Chanteperdrix
next prev parent reply other threads:[~2006-11-09 14:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-09 13:36 [Xenomai-help] Strange results with latency test Matthias Fechner
2006-11-09 14:04 ` Gilles Chanteperdrix [this message]
2006-11-09 18:36 ` Matthias Fechner
2006-11-09 14:12 ` Wolfgang Grandegger
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