How M1 Macs feel faster than Intel models: it’s about QoS

Re:How M1 Macs feel faster than Intel models: it’s about QoS by cmsj on Monday May 17, 2021 @08:25AM (#27182653)

I'm curious if there is some architectural limit that prevents Apple from doing something similar on Intel Macs, at least ones with 8+ cores. The scheduler could arbitrarily nominate 4 cores as "efficiency" cores and keep them for background tasks, leaving the rest free for "performance".

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Re:How M1 Macs feel faster than Intel models: it’s about QoS by twoodfin on Monday May 17, 2021 @08:38AM (#27182750)

I think the issue is that thermals, and thus overall efficiency, is optimized on the Intel chips when long-running work is split evenly across the cores.

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Re:How M1 Macs feel faster than Intel models: it’s about QoS by archi42 on Monday May 17, 2021 @08:54AM (#27182861)

Without knowing the inner workings of Apple's scheduler: I don't think there is any reasons this wouldn't work on x86 hardware. All you need is some API to tell the scheduler whether a task should be done "asap" or "whenever".

But you then get a huge tradeoff: If you reserve over 50% of the computational power for "asap" stuff, then all the "whenever" stuff will take twice as long as usual (assuming the tasks to be limited by compute power). On a 8C Intel that means that, for a lot of stuff, you're now essentially running on a 4C Intel. Given the price of these chips that MIGHT be a difficult sell, even for Apple. On the M1 they don't seem to care.

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Re:How M1 Macs feel faster than Intel models: it’s about QoS by kingsuper20 on Monday May 17, 2021 @03:39PM (#27187450)

>All you need is some API to tell the scheduler whether a task should be done "asap" or "whenever".

We could call it ::SetThreadPriority()

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Re:How M1 Macs feel faster than Intel models: it’s about QoS by agloeregrets on Monday May 17, 2021 @09:23AM (#27183090)

For intel that would cause some serious thermal issues. The Four E cores in the M1 use about the same amount of power as one big core (5w total). In an Intel chip that would mean the four 'E' cores would use probably 10 watts each, that's 40 watts cooking a chip.

Intel does have a chip for you though, they have a version with mixed UlV cores and big cores.

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Re:How M1 Macs feel faster than Intel models: it’s about QoS by Jiokl on Monday May 17, 2021 @10:12AM (#27183621)

Afaik, that isn't launching until 2021. https://en.wikipedia.org/wiki/Alder_Lake_(microprocessor) Or do you mean another CPU?

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Re:How M1 Macs feel faster than Intel models: it’s about QoS by gsnedders on Monday May 17, 2021 @11:28AM (#27184550)

Lakefield launched in Q2 2020 with the i5 L16G7 and the i3 L13G4.

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