Process "kernel_task" taking up almost 100% of CPU


macrumors newbie
Original poster
Dec 20, 2008
A few hours ago, I noticed my MBP start hanging and generally processing very slow. Apps would freeze at random times, and generally a lot of odd behavior.

I checked the activity monitor to see what might be causing this. It turns out, the process "kernel_task" is using almost 100% of my CPU. It has stayed within the 70-100% range, and has yet to go down. I tried many things, including restarting my Mac many times, but it remains the same.

Does anyone know why "kernel_task" is taking up so much of my CPU? Is there a way to somehow "reset" the process to get it back to normal? Any help would be much appreciated, since my Mac is, for just about all purposes, useless right now. It took me about an hour just to get to this page and type this message.
Thanks in advance!

P.S. I attached a screenshot of the process in the Activity Monitor. You can view it here:

EDIT: I just want to add that I think the "kernel_task" might have started eating CPU when I stopped a RAR program in the middle of extracting an archive. I'm not 100% sure though that this is when the problem started.​


macrumors 65816
Sep 19, 2009
I've heard that sometimes this may be connected to USB devices, as kernel_task provides these low level services.

Just don't kill the process (may result in a kernel panic).


macrumors regular
Jun 28, 2010
That's an underlying task, so it's difficult to troubleshoot because it can be affected by so many different things. Often it blows out in CPU usage if you have a dodgy network or external hardware connection. Disconnect form your network and see if that helps. Also disconnect any peripheral (one-by-one) to see if that helps.

Good luck!:)


macrumors newbie
Jul 2, 2014
High CPU usage

Hi, I have had the same issue with the CPU% running at 70%+.

I tried a restart and this didn't solve my issue.

HOWEVER, after putting my MacBook Pro into sleep mode for 10 seconds or so I brought it out of sleep and the kernel_tast that was sucking up all the CPU% dropped down to a couple of %.

Laptop is now back running how it should be... I hope this helps with others as its worked for me.


macrumors newbie
May 3, 2011
I've had this problem frequently. I assume that it derives from actions of an application, so I just starting quitting applications one after the other and then suddenly the CPU usage drops to almost zero. But I still haven't figured out which app is triggering this. I need to be more methodical and wait longer after quitting each app.