ARM MacBook vs. Intel MacBook • Hacker News Board

Re: ARM MacBook vs. Intel MacBook

#21

Post by STRML » Sat, Dec 12, 2020, 2:01 AM UTC

bognition wrote: post #11

Anecdotally I recently grabbed a M1 MacBook Air and it’s an incredible machine. I prefer it over my work issued 2019 pro. It could be that the MDM software has slowed down the pro, but overall the experience with the M1 is very good.

It's excellent. I have the 8-core i9 16" Pro and I prefer the Air in every way for development. The keyboard is better (no touchbar), it doesn't get as hot, the battery life is better, it's faster, and it cost 1/4 as much ($999 vs about $4k). I bought the 16" in February, only 10 months ago.

What a leap.

Re: ARM MacBook vs. Intel MacBook

#22

Post by STRML » Sat, Dec 12, 2020, 2:03 AM UTC

overcast wrote: post #2

Was expecting a bit more than a handful of paragraphs and three tests from this article.

People on HN still want to talk about the M1. It's just such an exciting product. So this will still sit on the front page for a while, despite the relatively terse source material.

Re: ARM MacBook vs. Intel MacBook

#23

Post by userbinator » Sat, Dec 12, 2020, 2:05 AM UTC

alwillis wrote: post #5

The M1 has 8 instruction decoders while every Intel processor maxes out at 4. This enables many more instructions in flight than on Intel. The M1 can process twice as many instructions per clock cycle than an x86 processor can.

An x86 instruction can decode into many more uops than an ARM instruction.

It could be more accurate to say the M1 can process twice as many half as complex instructions as x86.

Re: ARM MacBook vs. Intel MacBook

#24

Post by [deleted] » Sat, Dec 12, 2020, 2:06 AM UTC

theonemind wrote: post #9

Considering the positive reception of the M1, I'd like to see the cases where the M1 does sorely lose to the Intel chip as the post alludes to. The SIMD sounds promising in that regard, but I don't know processor technology that well. Does anyone know where the Intel chip greatly outdoes the M1?

[deleted]

Re: ARM MacBook vs. Intel MacBook

#25

Post by syberslidder » Sat, Dec 12, 2020, 2:10 AM UTC

syberslidder wrote: post #12

alwillis wrote: post #5

The M1 has 8 instruction decoders while every Intel processor maxes out at 4. This enables many more instructions in flight than on Intel. The M1 can process twice as many instructions per clock cycle than an x86 processor can.

4 x86 decoders, all modern x86 CPUs have micro-op caches that are wider than 4 and the retire width of the machines are 6 or greater. Saying it can process twice as many instructions per clock cycle is an incredibly incorrect statement.

To follow-up on my own point, once an x86 instruction has been decoded into a micro-op, it gets stored in a micro-op cache, where the vast majority of the frontend spends it's time fetching from. Additionally, "in flight" is a function of frontend width, Reorder buffer size, additional Out of order structures sizes and throughput depends on those plus the retire width. Additionally, IPC alone is a poor metric for performance analysis because run time is a factor of IPC and clock speed. M1 has higher IPC because it runs at around 3 GHz compared to x86 CPUs running at 4 or 5 GHz. Apple optimizes for IPC, they are all different tradeoffs. Lastly, Apple's cores are probably the biggest in the industry. Compare their new generation of cores, they had to jumbo-size every structure (much larger than most x86 cores). So while it is impressive from a design point, from a micro-architecture point their cores have ballooned in size and are on 5 nm. Their architects are very good, but not godly like I see many tech sites ascribe them to be.

Experience: Designed SPARC, ARM, and x86 CPUs

Re: ARM MacBook vs. Intel MacBook

#26

Post by vmception » Sat, Dec 12, 2020, 2:11 AM UTC

The only reason I would want more than 16gb RAM is for more room for virtual machines, so without that and it being cheaper than worse machines this is a hard yes, buy.

BUT the possibility of familiar OS' coming out with ARM versions (or just the x86 versions being emulated well), and the possibility of a more powerful M1-style processor with more than 16gb RAM anyway makes me want to wait.

But honestly if they roll out a better processing still with only 16gb RAM I guess I'll pull the trigger on one of the models.

Re: ARM MacBook vs. Intel MacBook

#27

Post by easde » Sat, Dec 12, 2020, 2:11 AM UTC

alwillis wrote: post #5

The M1 has 8 instruction decoders while every Intel processor maxes out at 4. This enables many more instructions in flight than on Intel. The M1 can process twice as many instructions per clock cycle than an x86 processor can.

This is an oversimplified statement. Extra decode width only helps if the rest of the CPU can actually process so many instructions in parallel without blocking on other resources like memory. x86 CPUs also have their own features to alleviate the limited decode width such as micro-op caches.

Case in point is the Samsung Exynos M3, which despite its 6-wide decoder is barely competitive with the 3-wide ARM Cortex-A76. The Exynos would fare very poorly against any recent 4-wide Intel or AMD CPU.

The crazy thing about the M1 is that every structure in the CPU is huge - the decoders, the ROB, the number of execution units, even the caches. And apparently all of it is implemented very efficiently.

Re: ARM MacBook vs. Intel MacBook

#28

Post by spideymans » Sat, Dec 12, 2020, 2:13 AM UTC

STRML wrote: post #21

bognition wrote: post #11

Anecdotally I recently grabbed a M1 MacBook Air and it’s an incredible machine. I prefer it over my work issued 2019 pro. It could be that the MDM software has slowed down the pro, but overall the experience with the M1 is very good.

It's excellent. I have the 8-core i9 16" Pro and I prefer the Air in every way for development. The keyboard is better (no touchbar), it doesn't get as hot, the battery life is better, it's faster, and it cost 1/4 as much ($999 vs about $4k). I bought the 16" in February, only 10 months ago. What a leap.

I've been using my girlfriend's M1 Air, and I am superbly impressed. You can feel how much more responsive the system is with every click. I am so tempted to upgrade my from my 2017 Pro. The only thing holding me back is the knowledge that the M1 is the slowest Macintosh chip Apple will ever make.

Re: ARM MacBook vs. Intel MacBook

#29

Post by jeffbee » Sat, Dec 12, 2020, 2:16 AM UTC

theonemind wrote: post #9

Considering the positive reception of the M1, I'd like to see the cases where the M1 does sorely lose to the Intel chip as the post alludes to. The SIMD sounds promising in that regard, but I don't know processor technology that well. Does anyone know where the Intel chip greatly outdoes the M1?

The only microbenchmark I've been able to produce that shows an Intel Tiger Lake as being faster than the M1 (mini) is in atomic primitives. For some reason taking and releasing contended locks is slow on this thing. Unclear if that's only because macOS doesn't have anything that can compete with futex. But all atomics seem slow, not just mutex.

In all other respects the M1 stomps the TGL.

Re: ARM MacBook vs. Intel MacBook

#30

Post by whymarrh » Sat, Dec 12, 2020, 2:19 AM UTC

agloeregrets wrote: post #17

What I found shocking is just how drastically faster some workflows are. If you work in JS and Node (say doing unit tests for an angular web app) this machine is so much better it’s unbelievable. It’s probably less than half the time to run tests. Half. It’s real productivity change.

And this is via Rosetta 2?