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From: Ingo Molnar <mingo@elte.hu>
To: Christoph Lameter <cl@linux.com>
Cc: Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org
Subject: Re: Scheduler regression: Too frequent timer interrupts(?)
Date: Fri, 17 Apr 2009 17:35:20 +0200	[thread overview]
Message-ID: <20090417153520.GA29968@elte.hu> (raw)
In-Reply-To: <alpine.DEB.1.10.0904171100510.21575@qirst.com>


* Christoph Lameter <cl@linux.com> wrote:

> On Fri, 17 Apr 2009, Peter Zijlstra wrote:
> 
> > And a random 1us cutoff, is well, random.
> 
> Its got to be somewhere.

Sorry, that's not a rational answer that makes any sense.

Peter's point is statistics 101: please show absolute values not an 
event distribution cutoff - how much total time do we spend in the 
kernel in that workload?

Is the overhead 1%? 2%? 0.5%? And how did it change from 2.6.22 
onwards? Did it go up by 0.1%, from 1% to 1.1%? Or did the average 
go down by 0.05%, while increasing the spread of events (thus 
fooling your cutoff)?

These are very simple, very basic, very straightforward questions - 
and no straight answer was forthcoming from you. Are you not 
interested in that answer?

	Ingo

  parent reply	other threads:[~2009-04-17 15:35 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 [this message]
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

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