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kernel_task is using 100% CPU when waking from sleep

Since updating my 13" mid-2013 MacBook Air to Mavericks, there's this issue that's been happening when I wake the computer up from sleep. A proccess called kernel_task uses 100% CPU (a whole core) and hangs there until the computer is restarted. This doesn't make the computer unresponsive, but it kills battery life.


So far, I've tried the following:


1. Resetting SMC, NVRAM and PRAM: no effect.

2. Safe Boot: the issue doesn't happen.

3. Deleting old apps/plugins: issue persists.

4. Closing all apps doesn't solve issue after it takes place.

5. Repairing permissions: no effect.

6. Apple Diagnostics: no issue found in hardware.

7. No kernel extensions from third-parties are installed (there are 120 kext, according to Terminal, but they all come from Apple).

8. Everything is up to date.

9. Only external plugin installed is Flash.


Given these, I reckon it's something software-related. Any tips on solving this would be welcome — things to look for in Console logs would be greatly appreciated.

MacBook Air (13-inch Mid 2013), OS X Mavericks (10.9)

Posted on Oct 28, 2013 12:03 PM

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323 replies

Sep 3, 2014 6:55 AM in response to zetanova

Hello MacPeople, can you please help with this problem? I've just spent all day to try to figure out. but didn't find an answer how to fix my problem.


So, I have MacBook Pro ME293 with Retina. In Activity Monitor there's Kernel_task that takes 650MB of memory space - I think it's too much for that 🙂


I try to figure it through Identify number, but My mac is v. 11.2 and this kind of file doesn't exist int the extension folder (the last one - 8.3)


What I should to do with it? Thanks for the answers!

Jan 13, 2015 9:59 AM in response to vaughanr

Exact same issue here, I have 2 LG monitors E2630 (23'') and 800% Retina Mac book Pro MacBookPro10,1 Mid 2012.


now I had to use one of the HDMI connector for one monitor and a thunderbolt (mini display port) connection for the other monitor.


could it be that it is because faulty Mini display port connectors? I dont have more than 2 in here 😟, anyone can check?

Aug 19, 2015 7:13 AM in response to HalexPereira

I'm having this issue since recently too (MBPr Mid-2012).

For me it always seems to happen when i'm running more than 1 virtual Machine with VMware Fusion. Even after i shut down all virtual machines the kernel task consumes every single bit of cpu it can (sometimes 700+ percent).


I always run using 2 external displays and the issue stops when i close the lid so the retina display is off. A second later the kernel_task drops to 0 cpu usage. As soon i open the lid again when it happened once kernel_task runs amok again.


Eventually i'm forced to reboot.

kernel_task is using 100% CPU when waking from sleep

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