Crawling MBP - "kernal_task"

LamboSE5 · Jul 15, 2013

Hey guys,

My early 2012 MBP is now running crazy slow and sluggish, with much more beach ball and just grindingly slow performance.

I look at activity monitor and there is a process called "kernel_task", the user is "root", and the percentage of CPU is 525-595 percent!! 91 threads and 594.3 MB real memory.

Details:
15" MBP Late 2011/early 2012
2.4 GHz Intel i7
8GB (now) Mem
AMD HD 6770M 1024
OSX Lion 10.7.5

I upgraded the RAM from 4 to 8 GB about 6 months ago, mainly because I wanted quicker performance in general and for doing multiple things; that said I never "tax" this computer at all, just internet/email/vlc movie/mail open maybe.
This upgrade didn't seem to do much for improvement.

Slowly my performance has been getting worse and slower.

I have ~750GB of space; which about 600 of was used but I cleared a bunch out recently so there's 540GB free now.

I don't know what this kernel_task crap is yet, i'm googling, but I don't remember seeing it in the AM list before; firefox is right under it at 21% CPU.

I've reset PRAM a few times, and might try to reset SMC or..MRS... or whatever that other accronym one was.

I only recently started using firefox (again) instead of safari, and I've recently added some add-ons to firefox and been using duck duck go search engine.

Anyways, any help is much appreciated
Thanks for your time.

G33Kster · Jul 15, 2013

Kernel_Task is normal and necessary

These may help you out:
https://forums.macrumors.com/threads/1368695/
http://reviews.cnet.com/8301-13727_7-20091848-263/kernel-task-taking-up-ram-in-os-x/

sofianito · Jul 15, 2013

LamboSE5 said:
Hey guys,

My early 2012 MBP is now running crazy slow and sluggish, with much more beach ball and just grindingly slow performance.

I look at activity monitor and there is a process called "kernel_task", the user is "root", and the percentage of CPU is 525-595 percent!! 91 threads and 594.3 MB real memory.

Details:
15" MBP Late 2011/early 2012
2.4 GHz Intel i7
8GB (now) Mem
AMD HD 6770M 1024
OSX Lion 10.7.5

I upgraded the RAM from 4 to 8 GB about 6 months ago, mainly because I wanted quicker performance in general and for doing multiple things; that said I never "tax" this computer at all, just internet/email/vlc movie/mail open maybe.
This upgrade didn't seem to do much for improvement.

Slowly my performance has been getting worse and slower.

I have ~750GB of space; which about 600 of was used but I cleared a bunch out recently so there's 540GB free now.

I don't know what this kernel_task crap is yet, i'm googling, but I don't remember seeing it in the AM list before; firefox is right under it at 21% CPU.

I've reset PRAM a few times, and might try to reset SMC or..MRS... or whatever that other accronym one was.

I only recently started using firefox (again) instead of safari, and I've recently added some add-ons to firefox and been using duck duck go search engine.

Anyways, any help is much appreciated
Thanks for your time.

How come a process uses more than 100% of CPU?

. It is not possible...

Watabou · Jul 15, 2013

sofianito said:
How come a process uses more than 100% of CPU? . It is not possible...

Perfectly normal. It's because of multiple cores.

OP: kernel_task is basically your operating system. You cannot kill the process or stop it, unless you turn the MBP off.

Also check if you installed any kernel extensions or what not. It''ll also be helpful if you post the screenshot of Activity Monitor on the Memory tab.

sofianito · Jul 15, 2013

Watabou said:
Perfectly normal. It's because of multiple cores.

525%-595% CPU usage, I don't buy it...

A process is either bound to a physical thread when CPU supports hyper-threading or to a physical core when CPU is in Turbo-boost mode (i.e. hyper-threading is disabled).

You can't have a process running simultaneously on 2 cores...

Watabou · Jul 15, 2013

Oh I thought you were confused why the number was bigger than 100%.

I didn't notice the 500+% though. Maybe this was a typo? The quad core's CPU limit should be 400%.

sofianito · Jul 15, 2013

Watabou said:
Oh I thought you were confused why the number was bigger than 100%.

I didn't notice the 500+% though. Maybe this was a typo? The quad core's CPU limit should be 400%.

It can't be more than 100%. As stated, when you run a process, it can only be bound to one core.

Watabou · Jul 15, 2013

sofianito said:
It can't be more than 100%. As stated, when you run a process, it can only be bound to one core.

Huh? If a process is multithreaded, then it can use multiple cores to run. Yes, concurrently.

BuCkDoG · Jul 15, 2013

Yes Watabou you are correct. You are able to go over 100% CPU usage due to the multiple cores and hyper threading.

sofianito · Jul 15, 2013

Watabou said:
Huh? If a process is multithreaded, then it can use multiple cores to run. Yes, concurrently.

You are right. After searching the web, it seems the %CPU usage in Activity Monitor is per all virtual processors. So, if you have a quad core with hyper-threading, a multi-threaded process could reach 800%. So, contrary to my thoughts, it seems software threads are not bound to the same physical core/threads as their process main thread.

Also, I always thought that threads concurrency was an illusion. I mean, process threads are run sequentially allowing a quantum of time for each thread. Based on the scheduling algorithm, the scheduler would choose which thread to run, and the dispatcher would bound it to CPU (context switching). Once its quantum is elapsed, the thread is unbounded and put on the wait queue, and another thread is allowed to run...,etc.

So if %CPU usage is > 100%, does it mean that process threads %CPU usage are accumulated? or does it mean that software threads are "really" run concurrently on several physical cores/threads?

Watabou · Jul 15, 2013

Yep, that's exactly it. The OS or the scheduler in this case, can allocate one or more threads to one process depending on several factors and can allow it to run on a specific core. So yes, they are really run concurrently on the physical cores and by doing so, they may finish faster, allowing the scheduler to remove it from the queue.

This is why it's normal to see CPU usage go over 100%. So if you see a process take 120% CPU, it just means that there are more than a single thread operating on that one process. The OS relinquishes the threads back to the system if the process doesn't require any more CPU time.

I maybe wrong on the specifics though. It's been a while since I took my OS class in uni.

LamboSE5 · Jul 25, 2013

I was wondering why I had no notifications about my thread here, hotmail has screwed up my account.

Anyways,
I've done some research on this issue, and I can't say I've seen even one single solution, maybe because "what IS the problem"?

My kernal task shows up to and over 600% now. It makes the computer feel almost unusable (if you're used to ANY type of speed or responsiveness at all).

I've tried resetting SMC, PRAM, booted in "safe mode" and tried to verify and repair disks (?) as one suggestion I found.
-Disk utility found on or to permissions that couldn't be ... reconciled .. or something. I took pics, I'll post later. And I'll learn how to take a screen pic for AC monitor.

Thanks for all of these responses guys!

LamboSE5 · Jul 31, 2013

..sssoooooo....

..what are your kernal task numbers? what's normal? surely 650% isn't normal.

What can I do?
Would a 'complete' reformat/reset of my computer fix the problem and how is that done on a mac?

LamboSE5 · Aug 20, 2013

Surprised there isn't a "STICKY" on this bs issue. Seriously, I think people wanting mousepad advice have a larger base.

I moved my files to an ext HDD and reformatted MBP.. seems to be working much better after the Lion re-install (from safe boot, no disc with MBP).

So far so good...? I'll try and update in a few weeks how it's handling.

Thanks guys.

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