TOP shows above 100% WCPU usage
Chuck Swiger
cswiger at mac.com
Thu Aug 17 16:48:45 UTC 2006
On Aug 16, 2006, at 10:28 PM, Bill LeFebvre wrote:
>>> 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.
You've got a good point here. In particular, consider the case where
you have an SMP machine where not all of the CPUs are running at the
same clock rate...100% of one CPU is not the same level of processing
as 100% of another.
--
-Chuck
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