From: Lee Revell <rlrevell@joe-job.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: 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: Mon, 25 Oct 2004 22:38:43 -0400 [thread overview]
Message-ID: <1098758323.9166.3.camel@krustophenia.net> (raw)
In-Reply-To: <1098626510.24073.9.camel@localhost.localdomain>
On Sun, 2004-10-24 at 15:02 +0100, Alan Cox wrote:
> Are you trying to use tsc for delays or measure CPU speed. The original
> question you asked was about CPU speed and the two are very different.
No we are only using it as a cheap way to do microsecond level timing.
Are you saying we should just use gettimeofday() instead?
jack_get_microseconds() is called at least twice per period which can be
several thousand times per second. Is the overhead of a system call
really low enough that this should work? rdtsc is definitely cheap
enough.
Lee
next prev parent reply other threads:[~2004-10-26 3:20 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
2004-10-24 14:02 ` Alan Cox
2004-10-26 2:38 ` Lee Revell [this message]
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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