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Old 08-23-2011, 03:41 PM   #1
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top showing up to 160% CPU usage

I'm trying to quantify the performance of a new s/w release and have been running "top -d1 -n600 -p920 > filename" to log CPU usage every second over a 10 minute period. A 3Ghz Pentium P4 gave a 10 minute average of ~68%. I then enabled hyper threading and get values peaking at 160 (% ??). Can this be regarded as 160 out of 200, or is it not as simplistic as that? If I average the hyper threading values I get 98, whereas dividing by 2 to get 49% would seem more appropriate
Old 08-23-2011, 04:14 PM   #2
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Hyperthreading involves taking a single processor and exposing it as two virtual processors, so yeah, it's pretty much 160/200 at that point.
Old 08-23-2011, 08:57 PM   #3
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Being a non-normalised number you can neither (safely) "average" the number nor "divide by 2".
You need to know the history of the usage - is one thread 100% busy on one "core", and the other 60% ?. 80/80 ? ...

But this is basically statistics I suppose, so use the numbers to prove whatever you want, just like everyone else does ...
Old 08-23-2011, 09:17 PM   #4
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In interactive mode you can toggle the CPU summary by hitting the '1' key to show individual cpus; see Section 3b


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