Process Using CPU Over 100%?

dgrizzell

macrumors member
Original poster
Jul 10, 2008
34
2
Nashville, TN
I was encoding an HD video today on my new iMac and was curious as to how well the processor was handling all the data. I checked the thread in activity monitor and noticed that the "% CPU" was reading over 100% and sometimes 200%. How does this work? I have a basic understanding of computer science but how does something run beyond 100% efficiency continuously like that without taking damage?
 

mrfoof82

macrumors 6502a
May 26, 2010
574
13
Lawton, OK
One core of the mult-core CPU is 100%, 2 cores are 200%, ect.
To be even more specific, this also applies to virtual cores. On an i7-equipped iMac, it's certainly possible for processes to approach 800% CPU utilization. I know HandBrake (thankfully) usually hangs around between 680% and 760% utilization for me.
 

PaulKemp

macrumors 6502
Jun 2, 2009
452
45
Norway
Is there a way to limit these applications? Specially apps like Handbrake and Plex Transcoding that uses so much.

I dont mind my CPU doing its job, but I do mind hearing fans in my living room.

edit: Ive looked at CPUTrottle, but that is PID based, and the PIDs change from one time to the next. I need something that uses the name of the application, and one session or instance can not use more than 50%
 

stridemat

Moderator
Staff member
Apr 2, 2008
11,179
592
UK
Is there a way to limit these applications? Specially apps like Handbrake and Plex Transcoding that uses so much.

I dont mind my CPU doing its job, but I do mind hearing fans in my living room.
Not that I know of. I do all my converting at night for that very reason.
 

Lucas Godfrey

macrumors 6502
Jul 12, 2010
306
88
Somewhere between Here and There
Is there a way to limit these applications? Specially apps like Handbrake and Plex Transcoding that uses so much.

I dont mind my CPU doing its job, but I do mind hearing fans in my living room.

edit: Ive looked at CPUTrottle, but that is PID based, and the PIDs change from one time to the next. I need something that uses the name of the application, and one session or instance can not use more than 50%
Don't worry, in over a year of heavy use I've never even heard my iMacs fans. The top and back get hot mind you, but the fans have always been quiet.
 

PaulKemp

macrumors 6502
Jun 2, 2009
452
45
Norway
Don't worry, in over a year of heavy use I've never even heard my iMacs fans. The top and back get hot mind you, but the fans have always been quiet.
I wouldn't mind it if they were quiet, the problem was the sound! :) Note that this is a Mac Mini i7 2011, not the iMac.

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Not that I know of. I do all my converting at night for that very reason.
I've reached out to the developer of CPUTrottle, it's a good little application, but as of now, you can only limit one PID. So, the problem in my case, is that Plex transcoding one movie has one PID, the next transcoding session has another. So in it's current version the applciation doesnt fill my needs.

The dev have however said that he might add some extra functionality, a GUI and maybe sell it on the app store. So this could be features coming in the near future!

source:
http://www.willnolan.com/cputhrottle/cputhrottle.html

edit: Also, the most current beta build of Plex Media Server (PMS) has fixed the insane CPU usage. Im using the bought version PMS 0.9.7.2
 
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