HalexPereira

Q: 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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Q: kernel_task is using 100% CPU when waking from sleep

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  • by MiracleWei,

    MiracleWei MiracleWei Feb 7, 2014 4:22 PM in response to HalexPereira
    Level 1 (0 points)
    Feb 7, 2014 4:22 PM in response to HalexPereira

    unplug the earphones may help sometimes

  • by DevArenaCN,

    DevArenaCN DevArenaCN Feb 7, 2014 11:14 PM in response to HalexPereira
    Level 1 (0 points)
    Feb 7, 2014 11:14 PM in response to HalexPereira

    My 13 MacBook Pro with Retina Display(LATE 2013) @OS X Mavericks 10.9.1 have the same problem. The tech support told me to shut down the Mac,and press option,control,shift and power key for 20 sec, and then turn it on again. But what's the point for that? This problem only exists after sleep....

  • by mtn.dewde,

    mtn.dewde mtn.dewde Feb 8, 2014 1:46 AM in response to DevArenaCN
    Level 1 (0 points)
    Feb 8, 2014 1:46 AM in response to DevArenaCN

    Yep, same for me. Apple support can obviously only help you solve superficial GUI stuff, don't listen to them.

     

    It's confusing because the process doesn't even show up in the activity monitor, you need to access it via terminal (top -o cpu) to see it's kernel_task.

     

    I followed MiracleWei's advice and unplugged my headphones, and it was gone after about 10 seconds. Not sure if it's coincidence or related... to lazy to try it out, too .

     

    edit: using late 2013 MBP

  • by DevArenaCN,

    DevArenaCN DevArenaCN Feb 8, 2014 1:51 AM in response to mtn.dewde
    Level 1 (0 points)
    Feb 8, 2014 1:51 AM in response to mtn.dewde

    it is related alright...wonder what reason that might be,but unplug the earphone does not help, I have tried.waiting for the next update, hope Apple can fix it

  • by mtn.dewde,

    mtn.dewde mtn.dewde Feb 8, 2014 1:58 AM in response to DevArenaCN
    Level 1 (0 points)
    Feb 8, 2014 1:58 AM in response to DevArenaCN

    yea me too. also, plugging in headphones and then starting music will sometimes cause the music to play on loud speaker for a split of a second - this is somehow related to standby too as it happens after waking from standby. probably some audio buffers not getting flushed properly - i don't know.

  • by jz-,

    jz- jz- Feb 8, 2014 4:46 AM in response to mtn.dewde
    Level 1 (0 points)
    Feb 8, 2014 4:46 AM in response to mtn.dewde

    You should be able to show it with Activity Monitor by going to View>All Processes, and changing the dock icon to show CPU usage helps too.

     

    I'm also having this issue, but removing headphones doesn't fix it, and it doesn't always occur with headphones in, so there might be two or more similar issues here. To those who can't fix this without a restart, the following steps always seem to fix it (temporarily) for me, hopefully it might for others too:

         Stop audio

         Quit any audio related applications that can access a microphone (and maybe remove headphones if they have an in-built mic)

         Sleep for 10-15 seconds, then wake

  • by kuerbiskopf,

    kuerbiskopf kuerbiskopf Feb 8, 2014 5:14 AM in response to drewrob26
    Level 1 (2 points)
    Feb 8, 2014 5:14 AM in response to drewrob26

    finally some good news

  • by mtn.dewde,

    mtn.dewde mtn.dewde Feb 8, 2014 5:30 AM in response to jz-
    Level 1 (0 points)
    Feb 8, 2014 5:30 AM in response to jz-

    cool, didn't know about the settings in activity monitor. thanks!

  • by northwest291,

    northwest291 northwest291 Feb 10, 2014 1:19 AM in response to HalexPereira
    Level 1 (5 points)
    Feb 10, 2014 1:19 AM in response to HalexPereira

    Ok, this is starting to get frustrating.

     

    I noticed that the kernel process goes through the roof with the Apple headphones connected, but not with any other kind of headphones?!?!

     

    Stupid.

  • by DevArenaCN,

    DevArenaCN DevArenaCN Feb 10, 2014 1:24 AM in response to northwest291
    Level 1 (0 points)
    Feb 10, 2014 1:24 AM in response to northwest291

    LOL,A nice way to find out ur headphones is real or not huh?

  • by Bart1977,

    Bart1977 Bart1977 Feb 10, 2014 1:44 AM in response to northwest291
    Level 2 (285 points)
    Feb 10, 2014 1:44 AM in response to northwest291

    My bluetooth headphones from a nameless brand had the same effect. But only sometimes, not always.

  • by Teddyph33r,

    Teddyph33r Teddyph33r Feb 10, 2014 3:18 AM in response to Bart1977
    Level 1 (0 points)
    Feb 10, 2014 3:18 AM in response to Bart1977

    northwest291 and Bart1977, I think that headphone-problem is because of mic input at apple headphones and same thing with bt headphones but not with normal audio-only-headphones.

     

    day to day I am more and more convinced that this problem is connected to mic input, not audio.

     

    I have 3 other MacbookPro's with Mavericks and none of those have this problem BUT those macs have seperate mic and headphone-inputs.

  • by tomasdev,

    tomasdev tomasdev Feb 11, 2014 4:16 PM in response to Teddyph33r
    Level 1 (4 points)
    Video
    Feb 11, 2014 4:16 PM in response to Teddyph33r

    Same issue on MacBook Air 10.9.1 with 8gb 1600 DDR3 & 1.7Ghz i7...

     

    1. Open VLC with a movie.

    2. Close the lid to let the computer sleep

    3. When you're back, sound is broken on VLC and kernel_task 100%...

     

    Seems like something Apple should fix, rather than a "plug and unplug headphones to fix"

     

    XOXO

  • by DaveSLR,

    DaveSLR DaveSLR Feb 12, 2014 1:34 PM in response to HalexPereira
    Level 1 (0 points)
    Feb 12, 2014 1:34 PM in response to HalexPereira

    Same 100% Kernel_task CPU usage on Macbook Air 2013.

     

    Somthings wrong with the sound software.

     

    i tryed so many things…

     

    to me, after StandBy works best:

     

    Check Kernel_tast on activity status app -> Close, or open iTunes -> what (~60sec.) till kernel_tast going back to normal (~2% CPU).

     

    [hope it's not the same Sh** like the gamma shift problem and so many more stuff that has never been fixed]

  • by Allen Watson1,

    Allen Watson1 Allen Watson1 Feb 15, 2014 4:49 PM in response to HalexPereira
    Level 1 (19 points)
    Feb 15, 2014 4:49 PM in response to HalexPereira

    On another thread about the same issue, I saw someone who said unintalling the app "Boom" fixed the problem. I discovered that simply KILLING the app (and not restarting it) fixed the problem. My kernel_task memory use dropped from 4GB+ to 786MB at once, and stayed there. I'm seeking a solution on the forums at the Boom vendor, Global Delight. Till then, no Boom.

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