From: Andi Kleen <andi@firstfloor.org>
To: "Chris Friesen" <cfriesen@nortel.com>
Cc: Christoph Lameter <cl@linux.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org
Subject: Re: Scheduler regression: Too frequent timer interrupts(?)
Date: Sat, 18 Apr 2009 09:59:11 +0200 [thread overview]
Message-ID: <87vdp2qto0.fsf@basil.nowhere.org> (raw)
In-Reply-To: <49E90F9D.5010308@nortel.com> (Chris Friesen's message of "Fri, 17 Apr 2009 17:24:13 -0600")
"Chris Friesen" <cfriesen@nortel.com> writes:
>
> Given that we're talking about tens of usecs of duration, statistical
> sampling may not work all that well.
He could just use oprofile with a small period. The minimum period for
CPU_CLK_UNHALTED is 6000 (and it could be probably lowered by tweaking
the events) oprofile counters on x86 can be configured to only count
in ring 0 So you would get an entry every 6000 ring 0 cycles. That
should give a pretty good picture where the kernel is spending time.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
prev parent reply other threads:[~2009-04-18 7:59 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-16 19:53 Scheduler regression: Too frequent timer interrupts(?) Christoph Lameter
2009-04-17 7:00 ` Peter Zijlstra
2009-04-17 13:42 ` Christoph Lameter
2009-04-17 14:16 ` Peter Zijlstra
2009-04-17 14:29 ` Christoph Lameter
2009-04-17 14:51 ` Peter Zijlstra
2009-04-17 15:04 ` Christoph Lameter
2009-04-17 15:28 ` Peter Zijlstra
2009-04-23 4:42 ` Pavel Machek
2009-04-28 21:02 ` Christoph Lameter
2009-04-28 21:23 ` Peter Zijlstra
2009-04-28 21:21 ` Christoph Lameter
2009-04-17 15:35 ` Ingo Molnar
2009-04-17 15:55 ` Christoph Lameter
2009-04-17 16:23 ` Peter Zijlstra
2009-04-17 16:33 ` Christoph Lameter
2009-04-17 16:49 ` Ingo Molnar
2009-04-17 17:19 ` Chris Friesen
2009-04-17 17:45 ` Christoph Lameter
2009-04-17 18:11 ` Peter Zijlstra
2009-04-17 18:20 ` Christoph Lameter
2009-04-17 18:58 ` Peter Zijlstra
2009-04-17 20:34 ` Christoph Lameter
2009-04-17 20:53 ` Peter Zijlstra
2009-04-17 23:24 ` Chris Friesen
2009-04-18 7:35 ` Ingo Molnar
2009-04-18 7:59 ` Andi Kleen [this message]
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