Topic: Kernel_task uses up all cpu% when charging my 2011 mbp at 75-95%
Just to make it clear - This is not an RME related issue! -
Just thought I should post here, as some people (including me) have had
problems with 2011 macbook pro's that have 10.7.x - 10.8.x OS installed.
This is my setup:
Macbook Pro 15" (early 2011)
2,2 GHz Intel Core i7, 8Gt 1333 Mhz DDR3, Intel HD Graphics 3000 512 Mt
OS X 10.8.2
Ableton Live 8.3.4
I've had some audio dropouts, and also my cpu usage has often gone through the roof.
I just couldn't figure out what was causing this. Actually I still don't know exactly, but now
I know when this happens, what happens, and how to avoid it.
Kernel task uses all cpu (about 200-700%) and causes OS X and apps to freeze and become
very very slow. -> I'm not able to perform with my macbook pro and audio setup at all.
When this happens:
Only when the battery is charging, and to be more precise, only when the battery capacity is
in between 75-95%. So the problem suddenly appears at 75% capacity and disappears when
the capacity reaches the 95% level.
(It took me a while to figure out when exactly this happens, as I usually have my macbook on
my rack fully charged when playing or performing.)
This started when I upgraded my early 2011 macbook pro to 10.8.1 - this was a clean install
(and same problem remains with 10.8.2) pram reset, nvram reset, disc repair, and permission
repair have no effect. I also installed the latest update (02/2013) that fixed some battery issues
with 2011 macbooks, but that didn't help either.
(With 10.6.8 I had no problems like this whatsoever!)
I suppose (I'm not a technician) that os x 10.8. might handle battery charging differently than
10.6.8. Maybe the battery draws more power when the charge is in between 75-95%, and either
the processor is unable to get enough from the 85W power supply, or this is a heat issue and the
battery heats so much that the processor can't handle the heat (although I think the fans are not
spinning at full speed, so this might not be the case), or possibly something completely different..
I also found some similar reports here: https://discussions.apple.com/thread/41 … p;tstart=0
I did send a bug report to apple, and hopefully they'll fix this. Meanwhile I can't recommend it for
anyone with a 2011 macbook pro to upgrade from 10.6.8.
Or if you already have, make sure to have your battery fully charged before an important gig. While
this might only concern a small percentage of 2011 mbp owners, I still think it's good to know that
this kind of a bug exists. At least I won't be upgrading my mbp to a new one before they release the
hashwell upgrade.. I'll just have to try and remember to keep my battery full.