From: Lee Revell <rlrevell@joe-job.com>
To: jonathan@jonmasters.org
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Robert Love <rml@novell.com>
Subject: Re: How is user space notified of CPU speed changes?
Date: Sat, 23 Oct 2004 21:40:56 -0400 [thread overview]
Message-ID: <1098582057.29081.157.camel@krustophenia.net> (raw)
In-Reply-To: <35fb2e5904102316177420f6a9@mail.gmail.com>
On Sun, 2004-10-24 at 00:17 +0100, Jon Masters wrote:
> On Sat, 23 Oct 2004 18:42:13 -0400, Lee Revell <rlrevell@joe-job.com> wrote:
>
> > Does anyone know how OSX/CoreAudio handles the situation? Apparently
> > realtime apps work flawlessly on speed scaling laptops under OSX.
>
> The difference in implementation between the Intel TSC and PowerPC
> TB[LU] has been mentioned previously in this thread.
Well, it was mentioned that there is a difference...
http://www-106.ibm.com/developerworks/eserver/pdfs/archpub2.pdf
pg. 39, "Non-constant update frequency".
"Each time the update frequency changes, the system software is notified
of the change via an interrupt, or the change was instigated by the
system software itself. At each such change, the system software must
compute the current time of day using the old update frequency, compute
a new value of ticks_per_sec for the new frequency, and save the time of
day, Time Base value, and the tick rate"
This was what I wanted to know: does Linux and/or the x86 have a similar
mechanism? Looks like the answer is no...
Lee
next prev parent reply other threads:[~2004-10-24 1:41 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-21 23:01 How is user space notified of CPU speed changes? Lee Revell
2004-10-22 11:23 ` 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 [this message]
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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