understanding CPU stats

[Jon M. Hanson]

On Friday 31 August 2007, alex at crackpot.org wrote:
> I'm trying to better understand the output of vmstat, specifically the
> difference between 'user' and 'system' cpu usage.  I have guessed that
> 'user' is all user programs, and 'system' is the kernel.  Is that right?
>
> I've just upgraded PHP versions, and I'm seeing much higher system cpu
> usage than prior to the upgrade.  Not sure what to attribute that to,
> or where I ought to look for optimization options.
>
> Memory usage looks about the same before and after.
>
> alex
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That is correct: The system percentage is the percentage of CPU instructions 
executed in the kernel and the user percentage is the percentage of CPU 
instructions not in the kernel and actively executing something (not idle).

What's going on on your system when you see the higher system time? Are PHP 
pages being interpreted? Maybe there is some caching on PHP code going on 
soit doesn't have to reinterpret it over and over again (like in a loop) and 
that cache is currently being populated.


-- 
Jon M. Hanson (N7ZVJ)
Homepage: http://the-hansons-az.net/
Weblog: http://the-hansons-az.net/wordpress/
Jabber IM: jon at the-hansons-az.net
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