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Date: Tue, 20 Nov 2007 11:41:28 +0300
From: Alexey Popov <lol@chistydom.ru>
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To: Kris Kennaway <kris@FreeBSD.org>
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Cc: freebsd-stable@freebsd.org, Ivan Voras <ivoras@freebsd.org>
Subject: Re: 2 x quad-core system is slower that 2 x dual core on FreeBSD
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Hi.

Kris Kennaway wrote:
>>>> CPU states:  9.5% user,  0.0% nice, 82.0% system,  0.5% interrupt,  
>>>> 8.0% idle
>>> A wild idea that might not help: try reducing kern.hz in loader.conf to
>>> something like 100 and see if something significant changes.
>> Now it runs with hz=100, number of context switches became ~ 2 times
>> less, but still there's 90% system CPU load (see attach).
> 
> System CPU usage doesn't tell you anything by itself, you need to look 
> at how much work the system is actually doing (pages served/second, or 
> whatever).  For example, when your kernel is getting more work done, 
> system CPU usage will also be higher.
Usually on PHP backends slow PHP code eats most of the CPU time. I have 
%user much bigger than %system in CPU states.

But now %system is much bigger than %user and I can conclude that on 
8-core server FreeBSD consumes more CPU time than PHP.

With best regards,
Alexey Popov