From: Robert Love <rml@tech9.net>
To: William Lee Irwin III <wli@holomorphy.com>
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: 09 May 2003 12:47:05 -0400 [thread overview]
Message-ID: <1052498824.867.8.camel@icbm> (raw)
In-Reply-To: <20030509070142.GU8978@holomorphy.com>
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.
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.
Robert Love
next prev parent reply other threads:[~2003-05-09 16:31 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 [this message]
2003-05-09 16:53 ` William Lee Irwin III
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
-- strict thread matches above, loose matches on Subject: below --
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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