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

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

#101

Post by grishka »

bjackman wrote: post #77

FWIW Android (and surely iOS, although I don't know anything about that in particular) have had systems like this for a long time. Aside from all the task scheduler smarts in the kernel itself, there are all kinds of things that can be marked as low priority so they run on the LITTLE (what Apple calls "efficiency") cores, while e.g. a UI rendering thread might go straight to a "big" ("performance") core even if its h…

While yes, the hardware had been there for a long time, Android hasn't been taking much of an advantage of it and I'm not quite sure it does now.

Google Play likes to do shit in the background. A lot of it. All the time. Even if you have deliberate RCE auto-update disabled in settings, it will still update itself and Google services, silently, in the background, without any way to disable that. And while it's installing anything, let alone something as clumsy as Google services, your device grinds to a halt. It sometimes literally takes 10 seconds to respond to input, it's this bad. It's especially bad when you turn on a device that you haven't used in a long time. So it definitely wasn't scheduling background tasks on low-power cores, despite knowing which tasks are background and which are not (that's what ActivityManager is for). My understanding from looking at logcat was that this was caused by way too many apps having broadcast receivers that get triggered when something gets installed.

Now, in Android 11 (on Pixel 4a), this was partly alleviated by limiting how apps see other apps, so those broadcasts don't trigger much anything, and apps install freakishly fast. That, and maybe they've finally started separating tasks between cores like this. Or maybe they started doing that long ago but only in then-current kernel versions, and my previous phone was stuck with the one it shipped with despite system updates.

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

#102

Post by kryps »

Keyframe wrote: post #94
kryps wrote: post #75

It does not just feel faster, in many cases it is faster. E.g. compiling Rust code is so much faster that it is not even funny. cargo install -f ripgrep takes 22 seconds on a Mac Book Air with M1, same on a hexacore 2020 Dell XPS 17 with 64GB RAM takes 34 seconds.

Are you counting download time as well? It took 8.30 sec on hexacore now when I tried it.

Nope, pure compile time on a Core i7-10750H with Windows and Rust 1.52.1, antivirus disabled. WSL did not make much of a difference though (29 seconds).

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

#103

Post by SigmundA »

kllrnohj wrote: post #76
Aaargh20318 wrote: post #59

Earlier quoted context omitted.

Shared graphics-memory is not the same as unified memory. In a shared graphics-memory system, a part of the system RAM is reserved for the GPU. The amount of RAM reported to the OS is the total RAM minus the chunk reserved the GPU uses. The OS only can use it's own part, and cannot access the GPU memory (and vice versa). If you want to make something available to the GPU, it still has to be copied to the reserved GPU…

> If you drop the 'user replaceable' requirement and place everything close together, you can have the benefits of both high bandwidth and unified memory Rather, if you drop the "big GPU" requirement then you can place everything close together. So called APUs have been unified memory for years & years now (so more or less Intel's entire lineup, and AMD's entire laptop SKUs & some desktop ones). It still ends up asso…

From the Anand article you linked further up:

"The first Apple-built GPU for a Mac is significantly faster than any integrated GPU we’ve been able to get our hands on, and will no doubt set a new high bar for GPU performance in a laptop. Based on Apple’s own die shots, it’s clear that they spent a sizable portion of the M1’s die on the GPU and associated hardware, and the payoff is a GPU that can rival even low-end discrete GPUs."

This is their first low end offering, they seem to be taking full advantage of UMA more so than anyone to this point. It will be interesting to see if they continue this with a higher "pro" offering or stick with a discrete CPU to stay competitive.

My guess is Apple will be the one to make UMA integrated graphics rival discrete GPU's, it will be interesting to see if that happens.

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

#104

Post by agloeregrets »

cmsj wrote: post #29

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".

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.

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

#106

Post by josephg »

kryps wrote: post #75

It does not just feel faster, in many cases it is faster. E.g. compiling Rust code is so much faster that it is not even funny. cargo install -f ripgrep takes 22 seconds on a Mac Book Air with M1, same on a hexacore 2020 Dell XPS 17 with 64GB RAM takes 34 seconds.

I did a side-by-side comparing with my friends' M1 macbook and my (more expensive, nearly brand new) ryzen 5800x workstation compiling rust. The ryzen was faster - but it was really close. And the macbook beats my ryzen chip in single threaded performance. For reference, the ryzen compiles ripgrep in 19.7 seconds.

The comparison is way too close given the ryzen workstation guzzles power, and the macbook is cheaper, portable and lasts 22 hours on a single charge. If Apple can keep their momentum going year over year with CPU improvements, they'll be unstoppable. For now it looks like its not a question of if I'll get one, but when.

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

#107

Post by agloeregrets »

ytch wrote: post #84
jackcviers3 wrote: post #23

So, like nice[1], except the developer sets the level of importance ahead of time? Makes sense, as long as I can reprioritize if needed. 1. https://en.wikipedia.org/wiki/Nice_(Unix)

Maybe like the big.little cores of many ARM CPU in Android phone? I'm not familiar with Android APP, maybe there are similar APIs in Android?

It's the same big.Little concept, slightly tweaked to allow this QoS work, I believe most of it was then used on Android but I doubt that Android uses the APIs well if they exist.

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

#108

Post by spideymans »

zelon88 wrote: post #48

That is all well and good. Great actually. And it makes sense. The high efficiency reduced instruction set computer has highly optimized architecture to improve efficiency. But we all knew that deep down. It's like the Ford Tempo. A mere 80 horsepower mated to a well designed and highly optimized transmission gave levels of performance that were higher than other cars in the same market. What I can't stand are all th…

>What I can't stand are all the people saying the M1 is capable of replacing high end x86 computers.

Whether or not this is possible completely depends on their unique workload. The M1 could probaly obviate any x86 chip for the average programmers. But that wouldn't be the case for gamer workloads, for example.

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

#109

Post by post_break »

nikanj wrote: post #74

My 16 inch pro Intel is plenty fast - for the first 45 seconds before thermal throttling kicks in. I have a feeling the M1 is faster because it can actually do work for more than just the briefest bursts

The problem I ran into the other day, had an app crash taking 50% of cpu. I was on the couch for hours on battery. Only noticed when my battery life was at 60% when normally it would be at 85%. My intel machine would have alerted me by burning my legs and trying to create lift with the fans.

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

#110

Post by Filligree »

kryps wrote: post #102
Keyframe wrote: post #94

Earlier quoted context omitted.

Are you counting download time as well? It took 8.30 sec on hexacore now when I tried it.

Nope, pure compile time on a Core i7-10750H with Windows and Rust 1.52.1, antivirus disabled. WSL did not make much of a difference though (29 seconds).

The Windows filesystem is extremely slow, even without WSL. It can be mitigated to some extent by using completion ports, but I doubt the Rust compiler is architectured that way--

You should benchmark against Linux as well.

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