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Date: Fri, 25 Nov 2005 07:45:03 +0100
From: Markus Trippelsdorf <markus@trippelsdorf.de>
To: Kris Kennaway <kris@obsecurity.org>
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Cc: freebsd-questions@freebsd.org
Subject: Re: so much clock interrupts?!
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On Thu, Nov 24, 2005 at 03:43:59PM -0500, Kris Kennaway wrote:
> On Thu, Nov 24, 2005 at 07:40:40AM +0000, Markus Trippelsdorf wrote:
> > On 2005-11-24, Wojciech Puchar <wojtek@tensor.3miasto.net> wrote:
> > > that's what i see in systat with FreeBSD 6.0/i386-SMP
> > >
> > >
> > >        540      534   99                                   pdwak  2000 cpu0: time
> > >                                                      16825 pdpgs  2000 cpu1: time
> > >
> > >
> > > on FreeBSD 5.3 live CD i have 100 not 2000 times per second
> > >
> > > isn't it too much?!
> > 
> > Yes it is.
> > That's why I have kern.hz="100" in my /boot/loader.conf .
> 
> Have you been able to measure a performance benefit from reducing it?
> Have you shown that reducing it does not cause your performance to
> *drop*?  It was increased for a reason..it actually increases
> performance on some workloads.
> 
Yes, I guess it increases performance on a high throughput webserver or
router that uses polling. 
But on the Desktop it only increases the overhead without any benefits
at all. 2000 interrupts per second per core for the timer is a 
ridiculous high number and I reduce it simply for aesthetic reasons.
This may be a religious issue and everyone should use what he or she
seems fitting.
-- 
Markus