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User profile for user: HalexPereira
HalexPereira Author
User level: Level 1
7 points

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
User profile for user: cyclix86
cyclix86
User level: Level 1
4 points

Jan 13, 2014 11:49 PM in response to milo jah

I have reproduced this on a late 2013 Retina MacBook Pro 13" (Mavericks 10.9.1) using the Sound settings window method. Have done it about 7 times to test, and it happens every time. The processor usage stays at 100% on core 0 for as long as the sound window is open (and by extension, as long as the microphone is enabled). CPU usage only comes back down to 0 about 30 seconds after closing the System Prefs window. Opening Sound prefs normally results in no abnormal processor usage.


I tried substituting the Sound | Input preference pane with plugging my earpods (with mic). With no programs running (not even system preferences) I observed the following with 100% repeatability:

Plug in Earpods -> close lid -> wait 60 seconds -> open lid -> kernel_task = 100% on core 0 -> unplug earpods -> wait ~5 seconds -> kernel_task = ~3% on core 0


The following also happens if you plug in the earpods while the machine is asleep, or in a small ~5 second window after waking the machine. If you plug them AFTER this window (once the machine is fully awake) everything works normally (~3% CPU usage from kernel_task). This seems to relate to the small window of activity normally seen by kernel_task when waking from sleep. From my experience, kernel_task uses 100% of core 0 when waking from sleep for about 5 seconds (may be machine dependant) before coming back down to around 0. This is normal, and is probably related with the hardware waking up. If, however, you plug the earpods in during this window (or if they were in when it was woken from sleep), this activity will continue indefinitely, or at least as long I was prepared to wait.


These are my experiences, as far I can tell they are 100% repeatable on my machine. Would be interested to see if anyone else has similar experiences.

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User profile for user: adilbek
adilbek
User level: Level 1
0 points

Jan 14, 2014 10:41 AM in response to HalexPereira

I reproduced this issue (plug earpods -> close lid -> ...etc.) on 3 different rMBPs in the apple store and reported to the technician. He opened a work order and said that he sent an email to Apple engineers. This was before Christmas so I am hoping to receive an answer any time now. Most likely, Apple will incorporate a fix in their next round of OS X update.

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User profile for user: bausi
bausi
User level: Level 1
23 points

Jan 16, 2014 7:17 AM in response to John_Raz

try the thing with ther kext as seen on page 3 of this thread i guess from 10.8.5! That ⚠REALLY⚠ solved my issue! MBA2013

John_Raz



Here how i have replace the AppleHDA.kext driver on my MacBookAir 13" (2013):


sudo mv /System/Library/Extensions/AppleHDA.kext /System/Library/Extensions/AppleHDA.kext.disabled sudo cp -pr AppleHDA.10.8.5.kext /System/Library/Extensions/AppleHDA.kext sudo chown -R root:wheel /System/Library/Extensions/AppleHDA.kext sudo touch  /System/Library/Extensions


Then reboot


Here the link to AppleHDA driver of Mountain Lion 10.8.5:https://dl.dropboxusercontent.com/u/112112/AppleHDA.10.8.5.kext.zip



cheers.mate!


Message was edited by: bausi

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kernel_task is using 100% CPU when waking from sleep

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