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David1986H

macrumors 6502
Original poster
May 12, 2020
493
376
Cheshire, UK
So im really looking forward to getting the 16" M1X MacBook Pro in October / November. I currently have the current 16" which still over heats when doing simple things like viewing twitch and/or 4k YouTube which gets up to 70c no problem.

But the biggest issues and most annoying is kernel_task using 500+% cpu sometimes which makes my mbp feel like 10 years old and even with a restart 10 minus later its back again and just have to wait it out.

Has anyone with an M1 Mac had kernel_task pop up over the last 9 months or so? Is it still a thing with the M1 Macs?
 
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leman

macrumors Core
Oct 14, 2008
19,530
19,709
Kernel task hogging the CPU time occurs when your machine is overheating. It’s a mechanism designed to take away available CPU time from your applications so that it can be parked and cooled down. If you are experiencing this behavior frequently, there might be an issue with your Mac, charger, battery or ambient temperature/airflow.

I honestly don’t know whether M1 Macs use the same mechanism, but they generally consume much less power and have less issues with heat, so I think your experience with them will be positive.
 
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Woof!

macrumors newbie
Jan 26, 2014
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kernel_task comprises a wide range of system processes being run, not just machine temperature regulation. I'd love to see some in-depth side-by-side comparisons.
 
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Kylo83

macrumors 601
Apr 2, 2020
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after updating to 12.3.1 my m1 max 16" which has insane batt now drops 1% every min doing nothing, my kernal_task is showing 585 cpu and memory what's happened
 

colinsky

macrumors regular
Apr 3, 2009
185
192
kernel_task was constantly bloating up on my m1 Mini, but it hasn't been as bad since 12.5 arrived.
 

mr_roboto

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Sep 30, 2020
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kernel_task CPU use is also a "symptom" of the kernel doing real work on behalf of user-mode processes, so don't leap to conclusions whenever you see it show up.
 
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wilberforce

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Aug 15, 2020
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kernel_task CPU use is also a "symptom" of the kernel doing real work on behalf of user-mode processes, so don't leap to conclusions whenever you see it show up.
True, although when it is using "600%" of CPU for extended periods with no obvious reason, it is usually a symptom of the computer throttling the CPU because the system thinks it is overheating (or it is actually overheating), and it uses kernel_task as a dummy process to deny CPU to real processes.
Just in case someone reading this does not understand what is going on.
 
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mr_roboto

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Sep 30, 2020
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Agreed, usually very high percentages over very long periods of time are throttling.

Usually you can see other processes using CPU which might plausibly cause lots of kernel_task CPU use. A common one is spotlight indexing, where the kernel's doing a lot of disk I/O on behalf of the indexer.

I wish Apple would create a separate in-kernel process name just for throttling so it would be easy to tell which of these two scenarios is happening.
 

Malus120

macrumors 6502a
Jun 28, 2002
697
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Agreed, usually very high percentages over very long periods of time are throttling.

Usually you can see other processes using CPU which might plausibly cause lots of kernel_task CPU use. A common one is spotlight indexing, where the kernel's doing a lot of disk I/O on behalf of the indexer.

I wish Apple would create a separate in-kernel process name just for throttling so it would be easy to tell which of these two scenarios is happening.
I couldn't agree more. "Kernal_Task" problems (often, but not always related to throttling) are extremely common and yet can often be very frustrating to troubleshoot (because it can be unclear, what exactly the problem is, and what is causing it.)

IMHO it's a symptom of the larger problem of Apple obfuscating the trouble shooting process on modern Macs. Combined with the decline in quality of Apple's phone/in person support, it turns almost any problem into a question of "can you solve it yourself" No? Do you still have a warranty? If yes, send to Apple and pray someone there can fix it (not gueranteed with "software issues" like this.)

Apple should really separate Kernal_Task (as well as several other processes) into their component processes and rationalize their error messages...

FYI as to the topic at hand, I don't have any issues with kernal_task on my 14" M1 Max.
 

Mike Boreham

macrumors 68040
Aug 10, 2006
3,931
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UK
Kernel task hogging the CPU time occurs when your machine is overheating. It’s a mechanism designed to take away available CPU time from your applications so that it can be parked and cooled down.

Very interesting! Not heard that before. If anyone but you had said that I would have been sceptical or looked for a smiley!

I have not seen Kernel Task mentioned in all the many discussions about throttling which surprises me a bit.

So is high Kernel task always linked to high temp? Are there other ways throttling is applied without ramping up Kernel task?

I use a chess analysis app which fully loads all the CPUs without Kernel Task being invoked and it gets hot. Implies sometimes machine recognises something not right and invokes Kernel Task before app is allowed to use more CPU.

Maybe not as simple as I am thinking!
 

leman

macrumors Core
Oct 14, 2008
19,530
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Very interesting! Not heard that before. If anyone but you had said that I would have been sceptical or looked for a smiley!

I have not seen Kernel Task mentioned in all the many discussions about throttling which surprises me a bit.

Thank you for your trust :) But don’t take this from me, take it from the main authority: https://support.apple.com/en-us/HT207359

So is high Kernel task always linked to high temp? Are there other ways throttling is applied without ramping up Kernel task?


I use a chess analysis app which fully loads all the CPUs without Kernel Task being invoked and it gets hot. Implies sometimes machine recognises something not right and invokes Kernel Task before app is allowed to use more CPU.

There are probably multiple mechanisms of temperature control. An obvious one is performance throttling (e.g. clock throttling or disabling execution units). The kernel task method relies on CPU time blocking instead. Unfortunately I don’t know the exact conditions when these safeguards are triggered. It might be good idea to check the logs for thermal events.
 

theorist9

macrumors 68040
May 28, 2015
3,883
3,067
Definitely sounds like thermal throttling to me, since I've experienced just what you described multiple times with my 2011 and 2014 MacBook Pro's. Don't know if you still have that 16" Intel MBP, but if you do the following might be helpful:

What's different with what's happening to with you vs. a normal kernel task is this:

1) Its percentage is extremely high.

2) Your computer has become essentially unresponsive. That doesn't happen normally even if you are running a set of processes that are using all the cores (e.g., run a program in each of x different instances in Terminal, where x = number of cores). In the latter case, the OS is smart enough to bump down the priority of those other programs when you actually need to interact with your computer. It will be a bit more sluggish than usual, but it won't be unresponsive like what you experience with thermal throttling. By contrast, with thermal throttling, the OS does the opposite because the point of the kernel task is to keep you from using the CPU much at all.

One simply way to test for thermal throttling is to point a desktop fan on high at the back of the MBP and see if it goes away, and then remove the fan and see if it comes back; repeat a couple of times. This is a sufficient but not necessary test for thermal throttling; i.e., if that happens consistently, you've got throttling; but if it doesn't, the test is inconclusive—you might still have throttling, but the fan isn't sufficient to make it go away.

More details on what I experienced: In both laptops, the OS would create a phantom high-load kernel task. I believe this didn't actually use the CPU, and that its purpose was to instead simply block off capacity so it couldn't be used by real processes, i.e., that it directed the scheduler to act as if most of the processing capacity was unavailable. Here's a screenshot from the 2014 MBP when it was happening:
1658987357781.png



An additional direct indicator of thermal throttling, at least in Intel machines, is that the CPU speed was slowed to 800 MHz (screenshot taken during same throttling event as above):

1661066660848.png


Thus between blocking off most of the processing cores (I think), and slowing the speeds of all cores to 800 MHz, all real processing on the CPU was slowed to a crawl (e.g., ~30 sec between when I pressed the keys to call up the force quit menu and when it opened).

My laptops were always connected to an external monitor, so the dGPU was always running, and my guess is that the throttling was due to dGPU overheating—especially since the CPU temperature wasn't very high; plus disconnecting the external monitor, which would cause the system to switch to the integrated GPU, would eliminate the throttling after about a minute. [Or I could keep the monitor connected but, as I mentioned above, aim a desk fan on high at the back of the laptop; this would also eliminate the throttling after about a minute.]

I forget the repair history with the 2011, but with the 2014 the problem appeared a couple of years after purchase, and Apple replaced the motherboard, but the throttling returned after a year. My guess is that there was a problem with the stability or application of the thermal paste. After the 2nd replacement, I had no further problems, so I guess Apple (or their repair center) found a better quality thermal paste (or a better way to apply it).
 
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