iTunes pegged my CPU at over 130%? | Comments (7)
Posted in Apple on 4th October 2006, 11:50 pm by Stuart
Today whilst I was working I noticed that my system (a MacBook Pro) had slowed to a crawl. To investigate I ran top from the terminal only to see this:
I then noticed the following dialogue when I switched to iTunes:
iTunes was updating my iPod with the few thousand pics I had dumped into iPhoto on the weekend and this had caused iTunes to work overtime to sync the photos across. What I’m interested to know is, how do you get more than 100% out of a CPU? Or is this some strange byproduct of the dual core intel? Answers on a postcard…
With two cores (or processors) you can get up to 200%. A lot of system monitors (MenuMeters, et al.) average the processor loads and only output up to 100% (which would mean both cores are pegged at 100%, for 200% total).
Apparently with dual processors you can go up to 200%. I found this out after I bought my first dual processor Mac four years ago, and imported lots of things at once in iTunes.
My guess is that the CPU blushed at the sight of what you store on the iPod. This caused more heating and the system read this as more processing. That’s where the wrong number came from.
The CPU load maximum is per processor (or core). Since your MacBook Pro has two cores, the maximum is 200%.
As you’ve got a dual processor system, and iTunes is multi-threded, the number can indeed go above 100% – you have 200% to play with.
@Feaverish, Mackie, Johan, David: Had to be didn’t it. Though it would be nice if top reported only up to 100% for a dual core CPU as that would make more sense imho.
@Christian: Quite probably!
I have a single core processor (G3 800MHz), and I’m seeing top reporting iTunes using CPU of up to 124%. this is with OSX 10.4. Any ideas why that would be?