more CPU being used than I have (?)

[Chad Perrin]

On Tue, Jan 25, 2011 at 01:02:46AM +0000, Craig Butler wrote:
> On Mon, 2011-01-24 at 16:57 -0700, Chad Perrin wrote:
> > I'm running a two-core laptop that, once in a great while, shows
> > approximately 250% CPU usage by a single process in top.  How exactly
> > does that work?
> > 
> > Note: It's not entirely surprising that this particular process is
> > consuming a lot of resources.  It's just surprising to me that it's
> > consuming more than CPUs * 100%.
> 
> Hi Chad
> 
> Its to do with top using weighted CPU percentage... for some reason this
> show peaks as more usage than 100% -- maybe something to do with the top
> averaging out over a specific time.
> I find that raw CPU mode gives a more accurate representation. 
> 
> raw mode is toggled by passing the -C argument to top.

Do you have a reference to a relatively simple explanation of how that
weighting works (and why)?

-- 
Chad Perrin [ original content licensed OWL: http://owl.apotheon.org ]
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