From: Jan Kiszka <jan.kiszka@domain.hid>
To: Brandt Erickson <brandt@domain.hid>
Cc: xenomai@xenomai.org
Subject: Re: [Xenomai-help] strange periodic behavior
Date: Tue, 13 Jun 2006 08:24:43 +0200 [thread overview]
Message-ID: <448E5A2B.9060606@domain.hid> (raw)
In-Reply-To: <45045.155.98.4.39.1150149018.squirrel@domain.hid>
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Brandt Erickson wrote:
> Hey all,
> I've been experimenting with writing a simple timer program using the
> native API. Basically, each loop, it writes the current timestamp into
> shared memory which then gets read by a slower loop and written to disk.
> The weird thing is, the period I get seems to always be half of what I've
> commanded. That is, if I set the frequency to 1000 Hz, the difference
> between each timestamp is a little over 2 ms (500 Hz). It works the same
> way for 10000 Hz and 20000 Hz. Does anyone know what causes this or how
> to fix it? Thanks.
> -Brandt
[FAQ] ;)
Is powersaving via CPU frequency scaling activated (my notebook, e.g.,
scales by 2 in that mode)? Make sure it's not. Also compare your
findings with the output of the latency test tool. Does it suffer too?
Jan
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next prev parent reply other threads:[~2006-06-13 6:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-12 21:50 [Xenomai-help] strange periodic behavior Brandt Erickson
2006-06-13 6:24 ` Jan Kiszka [this message]
2006-06-13 15:18 ` Brandt Erickson
2006-06-13 15:50 ` Jan Kiszka
2006-06-13 16:33 ` Brandt Erickson
2006-06-13 16:37 ` Jan Kiszka
2006-06-13 16:49 ` Brandt Erickson
2006-06-13 17:00 ` Jan Kiszka
2006-06-13 17:02 ` Jan Kiszka
2006-06-13 19:53 ` Brandt Erickson
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