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Date:      Thu, 17 Aug 2006 01:28:01 -0400
From:      Bill LeFebvre <bill@lefebvre.org>
To:        freebsd-stable@freebsd.org
Subject:   Re: TOP shows above 100% WCPU usage
Message-ID:  <44E3FE61.6060800@lefebvre.org>
In-Reply-To: <44E204C0.60806@rogers.com>
References:  <44E1F796.5070105@rogers.com>	<20060815172728.GB88051@dan.emsphone.com> <44E204C0.60806@rogers.com>

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Mike Jakubik wrote:
> Dan Nelson wrote:
>>> How can mysql use 160%? Is this a reporting bug in top because mysql 
>>> is threaded?
>>>     
>>
>> You have multiple CPUs, so a threaded process can theoretically reach
>> 100*ncpus cpu usage.
>>
>>   
> 
> Ahh, thats makes sense, thanks.

Actually it doesn't.  IMO, %CPU should be biased for all available cpu, not 
just a single cpu.  In other words, a single-threaded process running on a 
two processor box should never see more than 50% cpu.  That's how top 
computes it for SunOS.  But for freebsd top only displays whats in the proc 
structure and I don't know off-hand how the kernel records it.

Bill LeFebvre



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