Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

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

Reply
323 replies

Feb 19, 2014 12:39 PM in response to HalexPereira

am I the only one who considered getting an Apple Dev account ($100/year?) to get the possible fix in the 10.9.2 beta?


I tried to force stop/continue various processes at sleep and wakeup, and many combinations of them, using "sleepwatcher". I'm sure there are more processes and more permutations but I'm tired and fed up. I think I'm barking at the wrong tree by stopping/continuing processes.


My daily routine begins with a OS X update check lol

Feb 21, 2014 3:21 AM in response to HalexPereira

Hi


I've observed the same issue with kernel_task running hot, with it's CPU utilisation up in the > 80% arena, sometimes getting close to 100%.


I've not been actively monitoring with Activity Monitor, but did look when my 2012 MacBook Pro with Retina Display seemed to slow down from time to time.


I'm not using a wired headphone cable or Boom, but the suggestions did make me wonder whether iTunes was part of the problem - audio subsystem seemed to be the consensus.


I'm running iTunes 11.1.4 on Mac OS X 10.9.1 Mavericks.


I have seen a few crash reports from iTunes, normally when I wake up the Mac from sleep.


Therefore, putting two and two together, I terminated iTunes, and immediately saw the CPU utilisation for kernel_task drop down to single figures - as I write, it's sitting at 2.8%.


Therefore, audio does seem to be close to root cause.


Next time I get a crash report, I'll send it in, as per usual, but also link this forum thread to my report.


Cheers, Dave

Feb 22, 2014 5:47 AM in response to HalexPereira

Hi just FYI, for me the solutions was to disable third party kernel plugins (i was struggling with this two days instead of work…).


I had four plugins installed, I found them via this command:

kextstat -kl | awk '!/com\.apple/{printf "%s %s\n", $6, $7}' | open -ef


(plugins are located in: /System/Library/Extensions/)


I disabled only the soundflower extension because after googling all the plugins i found this information on soundflower:

According to OS X 10.8's GateKeeper application, Soundflower's app certificate has been revoked. GateKeeper recommends that you refrain from installing Soundflower 1.6.5.


I was going to disable all four but it seems the first one was the problem…

Feb 22, 2014 6:01 PM in response to laurent b

The particular issue mentioned on this thread looks to be specific to an audio related issue, when waking from sleep, on 2013 computers, with OS X Mavericks, leaving kernel_task between ~99-110% of CPU. The issue mentioned on that link occurs on older operating systems, and is related to throttling when there is a issue with the temperature sensors or cooling system.


kernel_task controls many things, and there are a number of ways its CPU usage can go out of control, but it looks like that post is referring to a different issue from the one this thread focuses on.

Feb 23, 2014 1:37 PM in response to HalexPereira

ℹ Good news everyone, the problem is fixed in OS X 10.9.2. I can put my MBA to sleep with earphones and Safari opened with flash content and the kernel_task bug no longer occurs. The update also fixes the occasional crash that can happen if you put your MBA to sleep and press a key or the trackpad at the same time.

Feb 25, 2014 8:06 PM in response to Community User

I am also having the issue where kernel_task is using 100% of the first CPU core when the cover is closed and in sleep mode. In fact today it happened again overnight and my battery was at 0% when I opened the Macbook Air. Only started happening after updating from 10.8.6 to 10.9.1.


I have now updated to 10.9.2 and hopefully it will fix this issue.

kernel_task is using 100% CPU when waking from sleep

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple ID.