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From: Lowell Gilbert <freebsd-questions-local@be-well.ilk.org>
To: Martin Turgeon <freebsd@optiksecurite.com>
References: <20101015071719.1536f19e@mail.ose.nl>
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Date: Mon, 18 Oct 2010 16:31:10 -0400
In-Reply-To: <4CBCA8D1.5040005@optiksecurite.com> (Martin Turgeon's message of
	"Mon, 18 Oct 2010 16:06:41 -0400")
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Cc: freebsd-questions@freebsd.org
Subject: Re: How is CPU usage calculated?
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Martin Turgeon <freebsd@optiksecurite.com> writes:

>  Le 2010-10-18 15:12, Adam Vande More a =E9crit :
>> On Mon, Oct 18, 2010 at 1:54 PM, Martin Turgeon
>> <freebsd@optiksecurite.com>wrote:
>>
>>> I didn't knew about -H to show individual threads, but my problem isn't
>>> there. My problem is that the summary printed in the first lines doesn't
>>> match the total of the process detailled under the summary. For example=
, I
>>> have a user CPU usage est 83.1% in the summary, but the only process wo=
rth
>>> mentionning in the list is mysqld that is taking 255.52% WCPU. That's f=
ar
>>> less than half the "CPU power" but 83% is far more. It's that difference
>>> that I don't understand.
>>>
>>> How is this possible?
>>>
>> man 1 top
>>
>> 83.1% doesn't mean what you think it does.
>>
> I just reread it and it isn't clearer what is using the CPU so
> much. Can you please give me a little more explanation?

They are calculated over different time periods, averaged in different
ways (that's they "weighted" part), and processes only show up until
they exit.