MBP stuttering - kernel_task using 100% of CPU

Discussion in 'macOS' started by in/flux, Jun 1, 2008.

  1. in/flux macrumors newbie

    Jan 23, 2008
    Hi all,
    This is my first Mac, and I'm not too happy with it.
    I'm forced to force-shutdown it daily (not even exaggerating), often when I'm doing work.

    Here's what's going on:

    At a random point during the day, my graphics will completely freeze. I can still move the mouse around, but nothing responds if I click it. After about 15-20 seconds of this inactivity, I have 5 or 6 seconds of it back to normal, and then it freezes again. This happens in an infinite loop.

    During that 5-6 seconds, I fire up Activity Monitor and see that immediately following this 15-20 seconds of inactivity, the process kernel_task is at 100 CPU (or somewhere around it.) Afterwards it immediately goes to 2 or 3 CPU - then after the 5 seconds of being able to click and stuff, it freezes again - this loops.

    I'm forced to hold down the power button and force-shutdown the system. It's extremely irritating.

    Does anyone know what is wrong?

  2. TuffLuffJimmy macrumors G3


    Apr 6, 2007
    Portland, OR
    It sounds like you are either experiencing hardware issues or a bad install of the OS. Try taking your computer to a genius at an Apple Store or do a full reinstall off of the DVDs that came with your computer.
  3. in/flux thread starter macrumors newbie

    Jan 23, 2008
    Could be. I can't do a reinstall though, I don't have a hard drive to put all my current stuff on.

    I've done a transfer though, and it was hell moving Library files and etc. I never want to go through that again.
  4. TuffLuffJimmy macrumors G3


    Apr 6, 2007
    Portland, OR
    you manually moved around system files? Well of course you're going to have problems!
  5. crazzyeddie macrumors 68030


    Dec 7, 2002
    Florida, USA
    yeah if you've been manually moving files around that could definitely be where the problem is coming from. You should really buy a backup hard drive just for general use, and then use that to backup all your files. Then do a clean install of the OS and migrate your data back over.

    You can actually automate the process if you clone your internal drive to the external and then use the Migration Assistant after you've reinstalled the OS on the internal drive. It takes 2-3 hours at most.

    If you don't want to buy the drive, you can pay the Geniuses to do this for about $75 at the Apple Store.
  6. ElectricSheep macrumors 6502


    Feb 18, 2004
    Wilmington, DE
    If you have the Developer Tools installed, you can try firing up Shark and performing a system trace. This will give a breakdown of where CPU cycles are being spent (even inside the kernel).
  7. in/flux thread starter macrumors newbie

    Jan 23, 2008

    Problem is that I would be losing all of the application files in the /Library and ~/Library folders. I didn't move anything I didn't need, however I know that Penryn MBP stuttering is a problem that others have, so it's not attributed to this.
  8. in/flux thread starter macrumors newbie

    Jan 23, 2008
    Will give that a try. Thanks!

    Any other insights?
  9. mathmarc macrumors newbie

    Jun 7, 2008
    What a coincidence. I am having the exact same issue with
    my brand new 1.8 GHZ MBA.I will be using ichat or watching a dvd
    and suddenly kernel_task takes up 100% on one of my CPU's, causing
    the entire machine to come to a halt. I have a clean install and
    a pretty vanilla machine. Ideas?

    THis is starting to get highly frustrating. (I am a long time mac user...)
  10. mktb macrumors newbie

    Jun 6, 2008
    Having the same problem. Any ideas?
  11. winder99 macrumors newbie

    Jul 22, 2002
    Anyone running Parallels VM? I've seen a similar thread on the Apple Discussions forum and that seems to be a common cause. (I'm running into it too).

    I'm going to try uninstalling Parallels and it's Kernel extensions and see if I run into this again.
  12. bamakodaker macrumors newbie

    Jun 26, 2008
    hope you guys have already solved this

    Just sounded like you started in what I think may have been the wrong direction. kernel_task problems are rather easily found online, even on Apple Support sites.

    I have a huge problem with kernel_task. In Activity Monitor CPU usage may go up to 80% or 92% or even "lock" or "hang". I'm not sure when the problem begins - with computer start, with connection to ethernet, or when opening Photo Mechanic when a card is connected to the computer. The drastic slowdown last up to perhaps 10 minutes.

    I did a little online searching. I believe the searches showed some shared problems - kernal_task problems could also be associated with server search crashes or something like that.
    Here are a few sites with help (?)

    Problems I saw mentioned with the kernel_task/server problems seem very related to my problems. That's just my thoughts. I searched in hope of finding something helpful.
    Here is from a link - http://docs.info.apple.com/article.html?artnum=305167

    Issue or symptom

    As clients search mounted network volumes, the kernel_task process (pid 0) on the server is allocated more and more RAM. System administrators may notice that the amount of RAM allocated to the kernel_task process may be close to 2 GB. On servers configured with 2 GB or 3 GB of RAM, this can result in server performance degrading, or the server becoming unresponsive, or restarting unexpectedly.
    Products affected

    * Mac OS X Server (Universal) 10.4.7 or later


    You can make the following change to /etc/rc.server to improve performance in this situation. This is recommended only if your server has 2 GB, 3 GB, or 4 GB of RAM.

    1. Make a copy of /etc/rc.server with this command:

    $ sudo cp /etc/rc.server /etc/rc.server.bak

    2. As the root user, open /etc/rc.server in the text editor of your choice. (Apple Script Utility or Terminal?)

    3. Locate this line in /etc/rc.server:
    sysctl -w kern.maxnbuf=90000

    4. Change the number 90000 to 20000, so that the line reads:
    sysctl -w kern.maxnbuf=20000

    5. Save the changes made to /etc/rc.server.

    6. Restart the server.

    Perhaps this will help.

    Best of luck!

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