From: William Lee Irwin III <wli@holomorphy.com>
To: Robert Love <rml@tech9.net>
Cc: Chris Friesen <cfriesen@nortelnetworks.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: how to measure scheduler latency on powerpc? realfeel doesn't work due to /dev/rtc issues
Date: Fri, 9 May 2003 09:53:59 -0700 [thread overview]
Message-ID: <20030509165359.GX8978@holomorphy.com> (raw)
In-Reply-To: <1052498824.867.8.camel@icbm>
On Fri, 2003-05-09 at 03:01, William Lee Irwin III wrote:
>> Why not just keep track of it in the scheduler? The statistic is well-
>> defined in terms of things measurable at context switch and wakeup.
On Fri, May 09, 2003 at 12:47:05PM -0400, Robert Love wrote:
> This would measure context switch latency. Or something.
> By definition, scheduling latency is the time from an interrupt which
> wakes the task up until the task is actually running.
> Historically, it has been measured by things like realfeel or amlat or
> whatever which generate interrupts and wake a waiting task up. You then
> measure the latency between the interrupt and when the task actually
> runs in user-space.
> So Chris can then go run this test under varying loads and see how bad
> the latency gets. I understand his question, but (sorry Chris) I have
> no idea of the solution on PPC.
Not at all. Just stamp at wakeup and difference when it runs.
-- wli
next prev parent reply other threads:[~2003-05-09 16:42 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-08 22:12 how to measure scheduler latency on powerpc? realfeel doesn't work due to /dev/rtc issues Chris Friesen
2003-05-09 0:13 ` William Lee Irwin III
2003-05-09 0:38 ` Davide Libenzi
2003-05-09 0:38 ` William Lee Irwin III
2003-05-09 0:56 ` Richard B. Johnson
2003-05-09 3:52 ` Chris Friesen
2003-05-09 4:13 ` Roland Dreier
2003-05-09 6:07 ` Chris Friesen
2003-05-09 4:26 ` William Lee Irwin III
2003-05-09 6:14 ` Chris Friesen
2003-05-09 6:20 ` William Lee Irwin III
2003-05-09 6:53 ` Chris Friesen
2003-05-09 7:01 ` William Lee Irwin III
2003-05-09 16:47 ` Robert Love
2003-05-09 16:53 ` William Lee Irwin III [this message]
2003-05-09 17:38 ` Chris Friesen
2003-05-09 11:37 ` paubert
2003-05-09 8:23 ` mikpe
2003-05-09 8:17 ` how to measure scheduler latency on powerpc? realfeel doesn Giuliano Pochini
2003-05-10 0:39 how to measure scheduler latency on powerpc? realfeel doesn' t work due to /dev/rtc issues Perez-Gonzalez, Inaky
2003-05-12 23:55 ` William Lee Irwin III
[not found] <493798056@toto.iv>
2003-05-12 5:04 ` how to measure scheduler latency on powerpc? realfeel doesn't " Peter Chubb
2003-05-12 5:08 ` William Lee Irwin III
2003-05-13 0:20 how to measure scheduler latency on powerpc? realfeel doesn' t " Perez-Gonzalez, Inaky
2003-05-13 1:02 ` William Lee Irwin III
2003-05-13 2:08 Perez-Gonzalez, Inaky
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