kernel_task consuming 150% CPU; system unusable

Question

Level 1

0 points

kernel_task consuming 150% CPU; system unusable

I am having an issue where the kernel is consuming an inordinate amount of CPU time. I am not sure whether the number given by activity monitor is a percentage, but it's ~150.

I have run dtrace on the kernel and it seems that it's spending a lot of time in the log_level function:

twiggy:Documents remenda$ sudo ./hotkernel.pl
Password:
Sampling... Hit Ctrl-C to end.

FUNCTION COUNT PCNT
<snip>
mach kernel`ml_set_interruptsenabled 2049 5.3%
mach kernel`machineidle 9827 25.4%
mach kernel`loglevel 22406 57.8%

My CPU temperature is 66 degrees C. Both cores are active, so I believe this problem to be distinct from the temperature-related core shutdowns in other threads.

Macbook Air, Mac OS X (10.5.4)

Posted on Sep 6, 2008 8:19 AM

Reply

Answer 1

Sep 6, 2008 12:13 PM in response to remenda

Did you install the latest Air update? In that case, that could be the reason. It prevents core shutdowns, but makes the kernel_task run crazy when the computer becomes hot.

Reply

Answer 2

remenda Author

Level 1

0 points

Sep 6, 2008 12:50 PM in response to ahostmadsen

Yes, I have installed all the latest patches. This behaviour happened before the patch and is still happening now.

Reply

Answer 3

Sep 10, 2008 8:37 PM in response to remenda

I am having the same exact problem. My machine is completely up to date with all patches. The processor usage by KERNEL_TASK is so high I can no longer use iTunes for music. Listening to music just cuts out from too much CPU activity!

From the time I boot my machine KERNEL_TASK takes over even if the machine is cool. Both processors are almost completely used up! My Mac is no longer any better than the Windows machine I just left behind, In fact when I need to do real work, I boot up my 4 year old Thinkpad. What a disappointment!

Reply

Answer 4

Sep 12, 2008 6:51 PM in response to remenda

Also having the same problems on my MBA. I cant say with total certainty, but I'd guess that this started happening after I applied the latest MBA update which solved the core shutdown problem. Sometimes it spends longer at max CPU with Kernel_task going crazy and sometimes its only a few minutes. This is my first Mac and I am a bit unsure about how to troubleshoot and isolate the problem. Can anyone give me the basic steps to diagnose this?

Reply

Answer 5

Sep 12, 2008 7:14 PM in response to ExcelonGT

I doubt there is anything to do. When the computer becomes overheated (which happens quite easily), instead of shutting down a core, it pushes kernel_task to 150% of cpu. I believe it's a hardware issue, and it appears no software update can solve it (except perhaps, coolbook?)

Reply

Answer 6

remenda Author

Level 1

0 points

Sep 13, 2008 3:39 PM in response to remenda

Called Apple. 90 days expired; must buy Applecare or they won't talk to me. $246.00 charged to credit card. Outcome after a bunch of random exercises and reboots: reinstall the operating system, reinstall all applications, call again if problem still exists. Sigh.

Reply

Answer 7

remenda Author

Level 1

0 points

Sep 16, 2008 5:48 PM in response to remenda

10.5.5 didn't help. Did I mention that Applecare asked me to take the battery out of my Air at one point? This calibre of help, for the low low price of only $246.

Reply

Answer 8

Sep 16, 2008 6:00 PM in response to remenda

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 and 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.

Reply

Answer 9

Sep 24, 2008 10:32 PM in response to remenda

I am having the same problem with my Air. I've tried everything, read every forum, installed CoolBook. Everything. The machine is running at 61'C (after 30 minutes use in a cool room, on a cooling deck), both cores are active.

This is beyond frustrating. My shiny new apple may as well be a chunk of scrap metal. I too am beginning to wish I hadn't bothered to move from my PC - at least back then I didn't have any false hope!

Why there is no way to debug this? WHAT THE **** IS HAPPENING, APPLE?

Reply

Answer 10

iBimmer

Level 1

0 points

Sep 26, 2008 1:35 PM in response to remenda

Have the very same problem on my MBA too. That "kernel task" eats the CPU alive. It just comes and goes from time to time.

We need a solution, Apple!

Reply

Answer 11

remenda Author

Level 1

0 points

Sep 27, 2008 6:51 AM in response to remenda

I uninstalled Microsoft Office 2008 and it seems to have solved the problem for now. Can I just confirm that you guys are also using MS Office?

Reply

Answer 12

remenda Author

Level 1

0 points

Sep 27, 2008 7:21 AM in response to remenda

Never mind, that didn't fix it after all. Now to try uninstalling Fusion.

Reply

Answer 13

Sep 27, 2008 9:45 AM in response to remenda

I don't think uninstalling programs will solve anything; you probably just waste time. The kernel_task goes crazy when the computer gets too hot, no matter what programs are running. It's a problem only Apple can solve, but I doubt a solution is forthcoming.

Reply

Answer 14

af3556

Level 1

0 points

Sep 28, 2008 4:39 PM in response to remenda

Same problem here (MBA / 10.5.4 / MBA Update 1.0). This has only occurred since the MBA Update.

Reply

Answer 15

Sep 29, 2008 12:21 AM in response to remenda

I'm on the verge of dropping my machine into the bin (it will fit nicely, as its sooooo thin).

Please, does anyone know a way to analyze what is at the root of the kernel_task activity? I've checked my system log, and probed I/O with iosnoop etc etc, but nothing obvious shows up. Isn't there a way to see what kernel_task is doing and/or why it's doing it?

The machine is not too hot, and the HD is not too full, and this will happen when no applications are running. The O/S is upgraded with all the latest updates, to 10.5.5

If only I hadn't given up my Thinkpad...

Reply