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sdneidich

macrumors member
Original poster
Feb 5, 2011
88
0
NC, USA
This caused some confusion for me, so I wanted to share with everyone.

Observation
While ripping some DVDs using HandBrake, I realized my mac was using a lot of system resources. I opened up Activity Monitor, and much to my surprise, the % CPU being used by HandBrake was ranging from 340 to 390 (!).

How was this possible? note: Core i7 processor, dual core 13 inch

What I think is the Answer
The i7 in this laptop is dual core, and has hyperthreading enabled. This means that the computer can operate as if there were 4 cores.
The process HandBrake is making full use of the hyperthreading (in fact, it displays at 24 threads) and is therefore maximizing the use of the processor.

Since up to 4 virtual cores can be maintained, the maximum % CPU usage is 400, not 100.


Can anyone with a more extensive knowledge of the subject confirm this?
 
This caused some confusion for me, so I wanted to share with everyone.

Observation
While ripping some DVDs using HandBrake, I realized my mac was using a lot of system resources. I opened up Activity Monitor, and much to my surprise, the % CPU being used by HandBrake was ranging from 340 to 390 (!).

How was this possible? note: Core i7 processor, dual core 13 inch

What I think is the Answer
The i7 in this laptop is dual core, and has hyperthreading enabled. This means that the computer can operate as if there were 4 cores.
The process HandBrake is making full use of the hyperthreading (in fact, it displays at 24 threads) and is therefore maximizing the use of the processor.

Since up to 4 virtual cores can be maintained, the maximum % CPU usage is 400, not 100.


Can anyone with a more extensive knowledge of the subject confirm this?


I believe you are correct. I think someone on the forum pointed out to me that OS X counts each core out of 100%, so dual cores it out of 200%, quad is out of 400%.
 
Yes you are correct, 100% x 2 because it is dual core and then multiplied by two again because it can handle two threads per core (hyper threading).
 
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