Understanding CPU usage in linux using "top" command for VLC usage

Question

I have 2 quad core processors and I cant seem to understand what "top" is telling me.

I run a VLC transcoding application and i currently transcode 8 streams and "top" shows me that I am using 200% of my CPU. Now for a Pentium 3 that would be horribly bad but I dont understand how Linux calculates CPU usage with multi core processors.

Does this mean that my both processors are utilized 100%? 2 cores at 100%?

I also ran ffmpeg application for the same purpose and I could run 8 instances at 90% each which seemed to me like each processoss would occupy 1 core.

VLC has much lower CPU usage footprint so I just want to make sure I am not killing the hardware.

"I dont understand how Linux calculates CPU usage with multi core processors" One core is 100%. — marekful, Jan 21 '14 at 14:51
Well, that would mean all of your CPU is utilised. Whether that's fine or not depends... But that means that all 8 cores are on 100%. — marekful, Jan 21 '14 at 14:58

score 2 · Answer 1 · answered Oct 25 '14 at 15:24

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The output of top stating %cpu = 200 could be that of two cores at 100% or all eight using 25%

Being that you have 2 quadcores the %cpu would range from 0 - 800%

answered Oct 25 '14 at 15:24

Scott

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Understanding CPU usage in linux using "top" command for VLC usage

1 Answers1