From: Lee Revell <rlrevell@joe-job.com>
To: linux-kernel <linux-kernel@vger.kernel.org>
Cc: Robert Love <rml@novell.com>
Subject: How is user space notified of CPU speed changes?
Date: Thu, 21 Oct 2004 19:01:49 -0400 [thread overview]
Message-ID: <1098399709.4131.23.camel@krustophenia.net> (raw)
This issue came up on the JACK (http://jackit.sf.net) mailing list.
Google was not helpful so I ask here.
JACK needs to know the CPU speed, in order to calculate the DSP load
among other things. It used to be a valid assumption that you could
calculate it on startup and it would not change.
Now with frequency scaling (apparently desktops do this as well as
laptops) this doesn't work anymore. Is there a sane way for jackd to be
notified when the CPU speed changes? Polling a file in /sys is not good
enough, the overhead is unacceptable and we need to know _now_.
Is this the kind of thing that would require the new kernel event
interface?
Lee
next reply other threads:[~2004-10-21 23:17 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-21 23:01 Lee Revell [this message]
2004-10-22 11:23 ` How is user space notified of CPU speed changes? Alan Cox
2004-10-22 14:12 ` Con Kolivas
2004-10-22 18:05 ` Lee Revell
2004-10-22 18:57 ` Andreas Dilger
2004-10-22 19:40 ` Chris Friesen
2004-10-22 19:46 ` Lee Revell
2004-10-22 20:28 ` Alan Cox
2004-10-22 21:46 ` Chris Friesen
2004-10-22 23:25 ` Lee Revell
2004-10-25 15:28 ` Chris Friesen
2004-10-23 5:10 ` Lee Revell
2004-10-23 10:53 ` Matthew Garrett
2004-10-23 21:19 ` Alan Cox
2004-10-23 22:42 ` Lee Revell
2004-10-23 23:17 ` Jon Masters
2004-10-24 1:40 ` Lee Revell
2004-10-24 14:02 ` Alan Cox
2004-10-26 2:38 ` Lee Revell
2004-10-26 4:05 ` Lee Revell
2004-10-23 23:35 ` Jon Masters
2004-10-23 23:36 ` Jon Masters
2004-10-24 14:04 ` Alan Cox
2004-10-25 5:53 ` Joel Becker
2004-10-24 20:02 ` Robert Love
[not found] <1098399709.4131.23.camel@krustophenia.net.suse.lists.linux.kernel>
[not found] ` <1098444170.19459.7.camel@localhost.localdomain.suse.lists.linux.kernel>
[not found] ` <1098508238.13176.17.camel@krustophenia.net.suse.lists.linux.kernel>
[not found] ` <1098566366.24804.8.camel@localhost.localdomain.suse.lists.linux.kernel>
2004-10-23 23:54 ` Andi Kleen
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