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Kernel_task on a new MacBook Air

239867 Views 209 Replies Latest reply: Oct 4, 2010 12:53 PM by JOMStar RSS
  • Richard from Sweden Calculating status...
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    May 13, 2008 9:39 AM (in response to PittAir)
    Tried it, didn't work.

    I just keep on rebooting my Mac several times every day - hoping the PC guys will not notice...

    Message was edited by: Richard from Sweden
    MacBook Air, Mac OS X (10.4.7)
  • Macsymus Level 1 Level 1 (0 points)
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    May 15, 2008 4:26 PM (in response to PittAir)
    Perhaps unrelated, but when I looked at the source of the majority of syslogd events I was receiving on an MBA, they were from MS Office. There is a new update available labeled "Office 2008 SP1". (I have weekly update enabled, and hadn't yet caught this one.) Perhaps it will address some of the "deprecated API" log messages accumulating in /var/log/asl.db.
    MacBook Air, Mac OS X (10.5.2)
  • nyc40d Calculating status...
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    May 28, 2008 5:24 PM (in response to my_precious)
    You folks are brilliant. I am totally guilty of using the MBA on the bed and then wondering why I get this CPU freeze! Mystery solved.
    MacBook Air, Mac OS X (10.5.3)
  • st3v3nc0lb3rt Calculating status...
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    Jun 5, 2008 7:51 AM (in response to st3v3nc0lb3rt)
    Quick follow-up. No change regarding USB devices. The laptop will still overheat due to the out of control kernel task with or without USB devices. However, it is far more common for this to occur when an external monitor & a USB keyboard & mouse are attached. Curiously, when kernel task goes berserk, uplugging USB returns the process to normal.

    We have also noted syslog to go berserk with Office '08, especially when printing.

    No fixes yet. Extremely frustrating!
  • Richard from Sweden Level 1 Level 1 (0 points)
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    Jun 12, 2008 11:51 AM (in response to Macsymus)
    I finally got this solution from my local Apple dealer! Gonna try it out as this problem seems impossible to get rid of. Seems like an engineering fault from Apple.
    MacBook Air 1,8 Ghz, Mac OS X (10.5.3)
  • Razzi Calculating status...
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    Aug 13, 2008 1:12 AM (in response to zinch)
    Hi. Nice to meet you.

    My MacBook Air had the same trouble.
    I tried several software approaches, but the trouble wasn't fixed.
    I took it to a genius bar, and the genius finally changed its logic board and thermal module.
    Now it looks good.
    MacBook Air (C2D1.6GHz, HDD), Mac OS X (10.5.4)
  • Kirosana Calculating status...
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    Aug 25, 2008 8:55 AM (in response to Cottonwood1162)
    Interesting. Having the issue as we speak (MBA, Activity Monitor was reporting 173% CPU usage by kernel_task), pulled the USB Ethernet Adapter out, and everything returned to normal. I had unplugged the Ethernet cable earlier today, not sure if that may have been contributing to the problem. Definitely seems like a low-level issue.
    XServe, Mac OS X (10.5.4), Administered from MacBook Air
  • KC Lawyer Calculating status...
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    Sep 2, 2008 12:05 PM (in response to zinch)
    I've had this problem since a few weeks after getting my MBA in March. However, I only now know that was the problem - so when Parallels was running and everything slowed down, I blamed Parallels; when I was giving a PowerPoint presentation and the videos slogged to molasses, I blamed PowerPoint. I did a complete system reinstall - clean (what an effort!). Then, I found this thread. Installed CoolBook Controller, and it seemed to work. But the bug came back (found out that I wasn't getting CoolBook to statup on login because of a registration problem, since fixed) and went to the Genius Bar. They quizzed me for a half hour then gave me a brand new MBA. Figuring all was well, I didn't run CoolBook on the new MBA. Same problem. CoolBook running again, all is well. Except for Apple's maddening deafness on why we have this problem.
    MacBook Air, Mac OS X (10.5.4), Mac user since 1984
  • Sigurd Level 1 Level 1 (10 points)
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    Sep 6, 2008 11:11 PM (in response to zboub75)
    A few observations:
    My configuration: MBA + 23" display, ethernet dongle and USB-powered hard-disk hanging off the display USB ports. MBA not running coolbook, but with the upgrade to avoid one-core shutdown under load.

    1) kernel_task going wild (130+% of CPU) on a regular basis.
    2) Unhooking either of the disk or the ethernet dongle from the display USB hub does NOT alleviate the problem.
    3) Unhooking the display USB and instead connecting the dongle (or the hard-disk) directly to the MBA DOES get rid of the problem.

    Tentative diagnosis: The display USB hub contributes to (or causes) the problem.

    Next step: Check how it works if I substitute the display USB hub with either an unpowered or a powered USB hub.
    MBA, MBP 15, Mac Pro dual quad, Mac OS X (10.5.4)
  • Sigurd Level 1 Level 1 (10 points)
    Currently Being Moderated
    Sep 7, 2008 5:11 PM (in response to Sigurd)
    Next experiment: Check how it works if I substitute the display USB hub with either an unpowered or a powered USB hub.

    So: Replaced the display USB hub with a Belkin powered hub (FSU233, 4 ports), with the time machine hard-disk and the ethernet dongle both plugged into the hub. The 23" display is still hooked up to the MBA (the mini-DVI-dongle) but it no longer serves as a USB device or hub.

    Result: after 15 hours of this, it still works well - no excessive kernel_task madness

    So it seems I have found a solution that works for me.
    MBPro 15, MB Air, Mac Pro dual quad, XServes, Mac OS X (10.5.4), Running Leopard server and clients
  • benbobaggins Calculating status...
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    Sep 15, 2008 2:00 AM (in response to KC Lawyer)
    Mine's been in the Apple repair centre for the last 10 days. Should be back with me soon. I wonder what they'll do to it.
    MacBook Air
  • Atul Kapadia Calculating status...
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    Sep 15, 2008 10:57 PM (in response to benbobaggins)
    Here is what I do - I have the 64 GB SSD version.

    - I close all tasks except the one I am actually doing (kill all other Firefoxes, Safaris)

    - Now the key: I make sure the left rear base of the computer is not on a fabric surface (like rug, pants, sofa). I actually hold the computer in the air (maybe that's why they called it MacBook Air).

    - After about 2-3 minutes, I notice a dramatic cooling of that side. It seems to me leaving the left rear (the side that gets hot) should have enough ventilation to dissipate it's heat to avoid the other core to shut down.

    Just my layman's solution. I have not yet tried CoolBook and hope today's update will fix it.

    Power Mac G5 Dual 2.5Ghz, 8 GB Ram, Mac OS X (10.5.2), MBA with SSD
  • justinweiss Level 1 Level 1 (0 points)
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    Sep 16, 2008 5:03 PM (in response to zinch)
    I don't know a whole lot about Mac OS internals, but I tried running Shark the last time this happened to me, and the results were dominated by machkernel::machineidle and AppleIntelCPUPowerManagement::pmInitThread and ::pmSlaveIdleThread. My best guess as to what's happening is that when the CPU temperature gets above a certain level, not only does the processor throttle down, but the machine runs an idle loop at a high priority to try to cool the processor down.

    Using CoolBook and locking the processor at 800MHz still results in decent performance, while I get ridiculously bad performance when CoolBook is disabled and the temperature gets above a certain threshold (which seems to be between about 65 and 70 degrees Celsius), so it's not just the processor throttling that's resulting in bad performance -- it's the idle loops in the kernel that take over the machine.

    Someone with more kernel knowledge than me would probably have to take a look to see if it's something that could be fixed in software. It would be really cool if someone (Apple or otherwise) could write a kext that would fix the problem, but I'm not holding my breath -- it seems like someone needs to find a line between poor performance and overheating the machine.
    Macbook Air 1.6, Mac OS X (10.5.4)
  • Marc Van Olmen2 Level 1 Level 1 (70 points)
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    Sep 16, 2008 6:21 PM (in response to justinweiss)
    My unit was a coreShutdown unit....I had my system drive erased reinstallled system (at Apple Store), still 10.5.4 and did update, it was working fine for a few days.

    Today don't have A/C running. 78 Farenheit/26 celcius, after doing 20min of iChat my Kernel task goes up to 130%. Of course video and audio is dropping, the video is getting slowed down.

    I tried now a few times to do iChat stuff and now in less then a minute I have this issue.

    Message was edited by: Marc Van Olmen2
  • remenda Level 1 Level 1 (0 points)
    Currently Being Moderated
    Sep 18, 2008 4:29 PM (in response to justinweiss)
    I ran dtrace on the kernel and it was spending all its time in the log_level function, which isn't documented anywhere I can find.

    Solution from applecare? Reinstall the OS and then all applications and then call us if the problem persists. This is the kind of thing I was trying to avoid by buying a Mac.
    Macbook Air, Mac OS X (10.5.5)
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