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Try charging on the right and not on the left

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Re: Try charging on the right and not on the left

#2
high CPU usage by kernel_task is caused by high Thunderbolt Left Proximity temperature, which is caused by charging and having normal peripherals plugged in at the same time.

Did anyone ever figure out why exactly the temperature sensor was making kernel_task go crazy?

Re: Try charging on the right and not on the left

#3
This doesn't make sense, and I'm a bit worried: I "cheaped" out and have a "left side only USB-C" MBPro from 2019.

Should I understand that having any kind of load on the measly 2 ports I have on my 1600€ computer will lead to abysmal performance? Like, attaching a USB hub to add basic necessity like HDMI or USB A?

Re: Try charging on the right and not on the left

#4
post #2

high CPU usage by kernel_task is caused by high Thunderbolt Left Proximity temperature, which is caused by charging and having normal peripherals plugged in at the same time. Did anyone ever figure out why exactly the temperature sensor was making kernel_task go crazy?

The comment by jksoegaard may explain it: "the purpose of the thread is to force idleness". I guess it uses up all the CPU without actually making the CPU do anything, so other processes can't use the CPU and produce more heat than it can handle.

Re: Try charging on the right and not on the left

#5
post #4
post #2

high CPU usage by kernel_task is caused by high Thunderbolt Left Proximity temperature, which is caused by charging and having normal peripherals plugged in at the same time. Did anyone ever figure out why exactly the temperature sensor was making kernel_task go crazy?

The comment by jksoegaard may explain it: "the purpose of the thread is to force idleness". I guess it uses up all the CPU without actually making the CPU do anything, so other processes can't use the CPU and produce more heat than it can handle.

That's very interesting. I didn't know it was possible for a process to use the CPU without using the CPU, as it were. Rather I thought the CPU usage was more or less a direct measurement.

Re: Try charging on the right and not on the left

#6
post #4
post #2

high CPU usage by kernel_task is caused by high Thunderbolt Left Proximity temperature, which is caused by charging and having normal peripherals plugged in at the same time. Did anyone ever figure out why exactly the temperature sensor was making kernel_task go crazy?

The comment by jksoegaard may explain it: "the purpose of the thread is to force idleness". I guess it uses up all the CPU without actually making the CPU do anything, so other processes can't use the CPU and produce more heat than it can handle.

Documented here: https://support.apple.com/en-us/HT207359

Re: Try charging on the right and not on the left

#7
post #5
post #4

Earlier quoted context omitted.

The comment by jksoegaard may explain it: "the purpose of the thread is to force idleness". I guess it uses up all the CPU without actually making the CPU do anything, so other processes can't use the CPU and produce more heat than it can handle.

That's very interesting. I didn't know it was possible for a process to use the CPU without using the CPU, as it were. Rather I thought the CPU usage was more or less a direct measurement.

From [1]

On processors that have a halt instruction that stops the CPU until an interrupt occurs, such as x86's HLT instruction, it may save significant amounts of power and heat if the idle task consists of a loop which repeatedly executes HLT instructions.

--

I don't know how it is implemented in darwin, HLT is a privileged instruction, then again it's kernel_task.

1: https://en.m.wikipedia.org/wiki/Idle_(CPU)

Re: Try charging on the right and not on the left

#8
post #3

This doesn't make sense, and I'm a bit worried: I "cheaped" out and have a "left side only USB-C" MBPro from 2019. Should I understand that having any kind of load on the measly 2 ports I have on my 1600€ computer will lead to abysmal performance? Like, attaching a USB hub to add basic necessity like HDMI or USB A?

Attach an LG Ultrafine 5K and you can fry an egg on your €3,300 laptop and use the white noise from the fan to sleep well.

Re: Try charging on the right and not on the left

#9
post #3

This doesn't make sense, and I'm a bit worried: I "cheaped" out and have a "left side only USB-C" MBPro from 2019. Should I understand that having any kind of load on the measly 2 ports I have on my 1600€ computer will lead to abysmal performance? Like, attaching a USB hub to add basic necessity like HDMI or USB A?

Yes. But the computer is very, very, very thin. Which sells more computers than actual performance under load.

Benchmarks show the MB having decent performance, as they start cold and don’t have external devices attached either. Thermal throttling only shows up once you’ve already bought

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