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Meaning Of CPU Utilization?

 
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Hi,

May be its gonna be innane question, but after google it out, could not find any suitable answer.
My question is "if task manager says, CPU Usage is 24%, then what one should conclude from 24%"?

Is it cpu time/memory? And how this percentage been calculated?

Thanks,
Ranu.
 
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Not an inane question, but not suitable for "beginning Java". Moving thread.
 
Campbell Ritchie
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I always thought that it meant, "if the maximum your CPU will do is 1000 megaflops per second, 24% means you are running at 240 megaflops per second." I might be mistaken however. Obviously the 24% is not very precise.
 
ranua agarwal
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Thanks Ritchie for the explanation.

Well, if you consider a JVM on a machine, then what it should be?
What i think, CPU utilization "Percentage of total amount of CPU time that the JVM has consumed since it was started.".
Correct me if i am wrong.
 
Campbell Ritchie
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No, because there are all sorts of other processes active apart from the JVM.
 
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Ideally, if you computer has 24% utlilization, it means that 76% of the time, it is doing nothing. It could be actually doing nothing (nothing is running). Or it could be waiting for stuff, like the network, the disk, etc., which in effect, for the processor is doing nothing.


Now, having said that, it could also mean that the number is wrong. For example, the new Intel i7 can timeslice eight threads (hyperthreading) on four cores. This is done internally to the processor. As far as the OS is concerned, it is a 8 core processor. This timeslicing can be done much better than the OS can do it... but since the OS thinks it is eight cores, then when it is passing 50 percent utilization, it should be nearly fully utilized.

Henry
 
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