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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

Reply
323 replies

Nov 24, 2013 7:07 PM in response to HalexPereira

Well I'm glad I'm not the only one experiencing this. Then again, not so happy. Just noticed it today as my computer came to a crawl. I'm on a 2013 MBAir with the Cinema Display plugged in via Thunderbolt. After I experience this and then restart, my computer will be stuck after the log in screen. It stays this way for an hour or so because I typically just give up and disconnect the Thunderbolt. After that, everything starts up fine. But then when I connect it again (so I can work), I noticed kernel_task eating up over 120% CPU, almost every time. So annoying!

Nov 25, 2013 10:59 AM in response to HalexPereira

I'm experiencing this as well. I've got a mid-2013 MacBook Air running 10.9. I don't use headphones often, nor VLC. Upon a clean reboot, with no head phones plugged in, if I put the MBA to sleep then open it back then I get the kernel_task 100% issue.


This is a problem for me because I rely on having a full day's worth of battery life for work. I upgraded from the 2011 MacBook Air to this one a few months ago specifically for the additional battery life. Now I'm getting 6 hours, which is less than what I was still getting on my 2011 model.

Nov 25, 2013 11:25 AM in response to HalexPereira

Alright, I solved my problem! Here's the situation (and thanks for whichever forum I found this solve).


To repeat, I was suffering this problem and my computer was at a crawl. Literally, opening up folders would be a drag just to get its contents listed.


I ran Disk Utlitiy and found a new error: "Live file system repair is not supported". Now, I'm one of those people to run Disk Utility about every other week but usually to fix partitions. I hardly ever run "Repair Disk" but this time I did and I saw this message in bright red which was a problem. So I did what anyone would do and startup in recovery mode and run Disk Utlity there. This time even more errors showed up such as my partition mapping was wrong and all of them were not able to be fixed.


Then I followed instructions to create a bootable Mavericks startup disk onto a USB drive (you can google this or find on one of the other forums). After what felt like eternity, it completed and I booted from the USB drive and was able to fix my Disk.


Anyway, that was this morning and with Activity Monitor running, "kernal_task" never goes above 25%, which still feels like a lot but definitely not the bogging down weight. It still feels like some sort of memory leak but at least my computer is now usable again until an update is available. Hope this helps some of you.

Dec 3, 2013 10:12 AM in response to HalexPereira

I'm here to CONFIRM this bug, its very easily recreated by keeping the headphones connected -> Sleep -> wait for 1 minute -> Resume from Sleep = 100% Kernel_task CPU usage.


Its just about time after all these posts that Apple takes a corrective measures.


Is Apple Monitoring these discussion groups to start with? or we are just barking?


MacBook Air 13 2013 (Maxed) running Clean Install of OS X 10.9 (Not Upgraded from Mountain Lion)!

Dec 3, 2013 10:37 AM in response to MyWillix

Looks like we're all experiencing the same issues.


Unfortunately for me, I can't reproduce it all of the time. For example, I was attempting to work last night and my computer experienced this bug and what should have taken 10 minutes turned into 2 hours because of the kernal_task. Then I had it running what I needed to all night, woke my machine up this morning to do another batch and kernal_task was down to a respectful 6%. Even when running my task, it stayed below 25%, like it should. Have no idea why as it was the exact same process. I just wish I could continuously reproduce it like you so that I could just disconnect the headphones to solve the problem temporarily.


Frankly, the only constant that brings up this bug is when i have my Thunderbolt display connected. Which I need. Plus, I never experienced this the first two weeks I upgraded to Mavericks.


Irregardless, Apple, please fix this bug!

Dec 3, 2013 5:26 PM in response to Qual30k

Apple Care doesnt do crap. I have collected logs for 2w now, nothing happens. My problem has nothing to do with headphones since it occurs all the time and I hardly ever use headphones. I had my MBP running all one and a half day maxing out kernel_task with nothing specific running (36h CPU time on 36h of uptime). I could have fried eggs on the lid and sent logs to Apple.

Dec 10, 2013 3:37 AM in response to Remuzzz

Ditto. Everyone is talking about headphones, but it isn't only that, it can't be because I have this problem and i never use headphones. I have a Jan 2012 imac 27" running Mavericks.
My kernel task is using 107% CPU and just under 1GB of RAM.

Apple just gets worse and worse in my view. They care less the more they sell. Pretty soon Apple will be the new Windows, and will match it for bugs and lack of giving a **** about it either.

Having a USP of caring and working hard for customers is great, and is a clear way to dominate a market, the sad thing is that once its worked, the USP goes out the window and is replaced by an insatiable desire for profit, quickly forgetting the very thing which caused the massive growth in Apple, i.e. QUALITY (including support).

I can't reboot because I am running a program which can't be stopped for 20 hours, it was only supposed to take 2 hours, until the Kernel task came along. AAAAAAGh

kernel_task is using 100% CPU when waking from sleep

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