Don’t Trust Activity Monitor on M1 Macs
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Don’t Trust Activity Monitor on M1 Macs
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Re: Don’t Trust Activity Monitor on M1 Macs
#2I don't get it. CPU graphs don't show power usage and they never have; they show how much time, percentually, a CPU was busy executing a certain type of task. You can never get a power estimate from a CPU usage graph at all. Even during normal operation purely on performance cores the clock speed will go up and down as the OS idles or new tasks get spawned. Whatever 10% is in your graph changes depending on the state of the system. This means the energy value in monitoring tools like these are bogus and should never have been trusted in the first place!
It's like trying to read the amount of gas left in the tank by looking at the odometer. Distance and fuel remaining are related, but there's no 1-to-1 connection going on there.
Different cores having different speeds is a difficult problem to solve for reporting CPU usage. The author seems to have missed the latest Intel CPUs which also have a performance/effeciency core setup, but I bet those suffer from the same "problem" as well.
Re: Don’t Trust Activity Monitor on M1 Macs
#3I don't get it. CPU graphs don't show power usage and they never have; they show how much time, percentually, a CPU was busy executing a certain type of task. You can never get a power estimate from a CPU usage graph at all. Even during normal operation purely on performance cores the clock speed will go up and down as the OS idles or new tasks get spawned. Whatever 10% is in your graph changes depending on the state…
Since Apple have full control over each Mac's hardware, couldn't they within a quite narrow average know how much power is consumed?
You also have hardware control chips like the T1/T2 that could help narrow this down even further.
I would get it for PC's, but here, it's quite different.
Re: Don’t Trust Activity Monitor on M1 Macs
#4If it's already messy in macOS, it's even messier in Windows:
https://devblogs.microsoft.com/oldnewthing/20210629-00/?p=10...
https://aaron-margosis.medium.com/task-managers-cpu-numbers-...
https://illuminati.services/2021/03/17/windows-10-task-manag...
Re: Don’t Trust Activity Monitor on M1 Macs
#5I'm torn, or maybe I misunderstood, from what I know about energy efficiency of CPU's, it has always been: Spend less time on the CPU.
If your task is short lived, or constrained by I/O, affining it to E cores is going to be better so that you don't have to "race to a stop-light".
But, to take an extreme example: having a 10w CPU awake for 24hrs vs a 30w one for 7 hours is going to be less energy efficient.
Re: Don’t Trust Activity Monitor on M1 Macs
#6I don't get it. CPU graphs don't show power usage and they never have; they show how much time, percentually, a CPU was busy executing a certain type of task. You can never get a power estimate from a CPU usage graph at all. Even during normal operation purely on performance cores the clock speed will go up and down as the OS idles or new tasks get spawned. Whatever 10% is in your graph changes depending on the state…
> CPU graphs don't show power usage and they never have
Sure, but Activity Monitor has separate CPU and Energy graphs, and the author here appears to be talking specifically about the Energy graph ("According to Activity Monitor’s Energy pane") rather than the CPU one.
Re: Don’t Trust Activity Monitor on M1 Macs
#7I don't get it. CPU graphs don't show power usage and they never have; they show how much time, percentually, a CPU was busy executing a certain type of task. You can never get a power estimate from a CPU usage graph at all. Even during normal operation purely on performance cores the clock speed will go up and down as the OS idles or new tasks get spawned. Whatever 10% is in your graph changes depending on the state…
I don’t think the article only looked at CPU graphs (FTA: “According to Activity Monitor’s Energy pane”)
https://support.apple.com/en-gb/guide/activity-monitor/actmn...:
- In the Activity Monitor app on your Mac, click Energy (or use the Touch Bar).
To display more columns, choose View > Columns, then choose the columns you want to show.
The energy use of individual apps and their processes is displayed in the upper part of the Activity Monitor window.
- Energy Impact: A relative measure of the current energy consumption of the app (lower is better).
Re: Don’t Trust Activity Monitor on M1 Macs
#8I don't get it. CPU graphs don't show power usage and they never have; they show how much time, percentually, a CPU was busy executing a certain type of task. You can never get a power estimate from a CPU usage graph at all. Even during normal operation purely on performance cores the clock speed will go up and down as the OS idles or new tasks get spawned. Whatever 10% is in your graph changes depending on the state…
Since Apple have full control over each Mac's hardware, couldn't they within a quite narrow average know how much power is consumed? You also have hardware control chips like the T1/T2 that could help narrow this down even further. I would get it for PC's, but here, it's quite different.
Yes.
But why would they? There's no benefit for them.
Re: Don’t Trust Activity Monitor on M1 Macs
#9> 100% active residency of an E core running at maximum frequency uses around 100 mW, and the same active residency of a P core running at its higher maximum frequency uses ten times that amount, 1000 mW.
Damn, that's a lot more efficient!
Re: Don’t Trust Activity Monitor on M1 Macs
#10> just as they would on an Intel processor with its identical cores.
Whilst its true that all intel macs have identical cores, the latest intel architecture also has Efficiency cores that are different from the performance cores.