What is a kernel_task and how to fix its high CPU usage
When we buy our Macs and think of how powerful they should be, we usually take into consideration the requirements of our everyday tasks — text editors, web browsers, email and calendar apps, etc. What we don’t think about is how much memory and CPU will be consumed by Mac’s default processes. Surprisingly, sometimes those tasks can overheat your Mac and even stall it completely.
One of the most popular culprits (or default Mac processes) for spiking up your CPU is a kernel_task. But don’t worry. The kernel_task high CPU issue is well-known and documented by now, so we have the exact steps you need to take to stop the kernel task taking up CPU it doesn’t need and prevent it from happening in the future.
Let’s start with what the Mac kernel_task CPU process is and how to find it.
What is a kernel_task process?
Just like many other processes that sound unfamiliar, kernel_task is essential to your Mac (as implied by its name), turns on as soon as you start your machine and runs in the background by default.
For the most part, kernel_task stays quiet. But it has one important function — it springs into action when it detects that your Mac’s temperature is rising, or that some apps are starting to use too much CPU and thus heating up the processor. The primary goal of kernel_task is to bring your Mac’s internal temperature back to normal.
You can often find kernel_task high memory and high CPU usage explanation in that it is itself a highly demanding process. But it’s not so. What kernel_task is doing is taking over your CPU to prevent other tasks from using it. It essentially throttles all the other processes, waits until they calm down, and then releases all the available CPU once again. But, of course, it doesn’t always go as planned.
To see how much the kernel_task memory usage and CPU usage, you can use Activity Monitor:
- Go to Applications ➙ Utilities ➙ Activity Monitor
- In the Process Name column, find kernel_task (or use search)
- Look up the CPU percentage in the % CPU column
- Switch to the Memory tab to check RAM consumption
Why is kernel_task hogging CPU?
So most of the time, kernel_task just throttles other processes temporarily. But what if it grabs the reins of your Mac’s CPU and doesn’t let go, or starts exceeding 100% of CPU? Most likely, it’s a fixable bug that you should try to address as soon as possible.
Here are just some reasons for kernel task taking up CPU problem:
- Too many Mac apps using too much CPU so that kernel_task can’t handle them effectively
- Your Mac is overheating because of charging
- Your Mac is overheating because your internal fan is not working properly
- You have a buggy Adobe Flash Player installed
- Third-party hardware drivers or auxiliary tasks called kexts are corrupt
- You might have some malware on your Mac, likely in the form of a cryptominer, scareware or adware
- Aggressive browser extensions could also cause the kernel_task high CPU issueHigh
- Thunderbolt Left Proximity temperature. Apparently, charging your MacBook Pro on the left side while having other peripherals connected increases the temperature, which causes kernel task CPU issues.
When it comes to monitoring your Mac kernel_task CPU issue continuously, keeping Activity Monitor running is not the best solution. Instead, it’s better to use iStat Menus, which lives in your menu bar and gives you much more precise real-time data.
iStat Menus is the most comprehensive Mac monitoring solution today. Not only does it collect data for CPU loads but also memory, battery, disk health, temperature, network activity, fans, and much more. This app gives you all the key indicators in intuitive charts, available in one click from your menu bar.
Can you quit Mac’s kernel_task?
You might wonder — if it’s this kernel_task that’s the culprit of all the troubles, can’t you just quit it like other processes?
The answer is no, because kernel_task is integral to the proper functioning of your Mac. At best, you won’t have any luck quitting it. At worst, you might actually damage some of your system files, especially if you try removing kernel_task using Terminal.
How much CPU usage is too much?
Since kernel_task is always running, you might be asking yourself what’s the acceptable CPU level for it to reach and when should you be worried?
It would be fair to say that the normal level of kernel_task memory usage and CPU usage is quite negligible and should never interfere with the day-to-day activities on your Mac. Most of the time, kernel_task should stay well below 10% of your CPU. Occasional spikes up to 50% or 60% are fine as well.
However, when you see kernel_task taking up CPU in the range closer to 100% or even more, your Mac is trying to do more work than it has the capacity for. It will then heat up and grind everything to a halt. This is when you know you have to intervene.
How to fix kernel_task high memory and CPU consumption
There are a few ways to fix all the kernel_task high CPU issues described above.
Charge your Mac on the right. You won’t believe this, but your MacBook Pro could misbehave because you’ve connected the charger on the wrong side. Specifically, kernel task issues arise when you connect the charger on the left, plus you have some other peripherals connected. Here’s how to fix it:
- Move the charger from the left to the right side of your Mac
- Unplug other peripherals from the left and wait until your Mac is fully charged
- In iStat Menus, open Sensors > Fans, and force your fans to max.
Note that you shouldn’t plug everything in on the right side, either, because it will cause your Mac to throttle, even though it won’t be a kernel task issue. Try having peripherals evenly connected on both sides. You can use iStat Menus sensor monitor to track how the temperature changes, depending on where you plug in your charger and peripherals.
Restart your Mac. While you can’t quit the kernel_task process, restarting your Mac essentially does just that, since all the tasks would start anew when your system reloads.
Quit useless processes. To do so, launch Activity Monitor, select any useless process, click the Stop icon, and then select Quit or Force Quit.
Disconnect your Mac from charging. If you’re using an unofficial charger for your Mac, it might easily cause overheating. Alternatively, try moving to a space that’s less hot or turn on the AC (especially on a hot summer day).
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Using CleanMyMac X to optimize your Mac’s CPU is very easy:
- Launch CleanMyMac X
- Navigate to the Malware Removal tab
- Click Scan
- Remove any malware if necessary
- Go to Optimization and remove any Launch Agents you don’t need
- Move to Extensions and uninstall any third-party browser add-ons you don’t use
Reset your Mac’s SMC. System Management Controller (SMC) is an important low-level component that is responsible for things like your battery, fan, and keyboard. Restarting it might correct any bugs causing kernel_task to misbehave.
On new Macs with a T2 security chip, you need to turn off your Mac and then press Control + Option + Shift (on the right side) for seven seconds. Add the power button. Release the four keys after 10 seconds. On older Macs, use the left Shift instead.
Since Apple Silicon Macs don’t have the SMC, you can just turn them off for 30 seconds and turn them back on again.
Throttle CPU usage manually. In many instances, kernel_task is either too late or too powerful or not powerful enough. But you don’t have to rely on it to make sure none of your apps go overboard with their CPU usage. You can just use App Tamer.
App Tamer is a fantastic utility that lets you monitor the amount of CPU used by all the processes from your menu bar and also set precise limits to that amount.
Here’s how it works:
- Launch App Tamer
- Open the app from the menu bar
- Click on any process you’d like to throttle
- Check “Slow down this app if it uses more than:”
- Enter the exact percentage or use the slider. Done!
Now you know why is kernel_task hogging CPU on your Mac. More importantly, you know quite a few ways to fix it quickly, whether it’s restarting your Mac or resetting your SMC. Even better, you can get rid of malware, heavy browser extensions and useless launch agents with CleanMyMac X, monitor your CPU usage with iStat Menus, and manually set app CPU limits with App Tamer.
Best of all, iStat Menus, CleanMyMac X, and App Tamer are available to you for free for seven days through the trial of Setapp, a platform with more than 220 majestic Mac apps that can solve any task you can imagine, from calculating using natural language (Numi) to compressing files on the fly (Squash). Try every Setapp app at no cost and see how your Mac speeds up and your productivity increases.