Re: cpu usage in 7.0

From: Ivan Voras <ivoras_at_freebsd.org>
Date: Sun, 24 Feb 2008 22:00:22 +0100
Kris Kennaway wrote:
> Hugo Silva wrote:
>> Kris Kennaway wrote:
>>> Barney Cordoba wrote:
>>>> I have a dual core system running 7.0 and I can't get
>>>> top to show more than 100% usage no matter how I
>>>> hammer it. My MAC shows over 100% often, but its not
>>>> clear if top is averaging the 2 cpus or just not going
>>>> over 100, or just showing 1 of the cpus.
>>>
>>> 100% in FreeBSD means "all of your CPUs are completely active".  It 
>>> is hard to exceed this amount :-)
>>
>> You should see my production mysql going over 458% on service startup, 
>> on a quad core server :-)
> 
> That is a multithreaded process using multiple CPUs, not the total CPU 
> statistics (first line of top(1)).

So how does a multithreaded process get 458% CPU on a quad-core machine? 
:) (Really, I want to know; I thought thread CPU accounting was fixed in 
7.x. Unless I'm mistaken, 4 CPU-intensive threads in a single process 
should account as 4 CPU-intensive single-thread processes; i.e. each 
could only take up to 100% of a core/CPU, accounting for NCPU*100% total).


Received on Sun Feb 24 2008 - 20:00:36 UTC

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