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AMD claims Arm ISA doesn't offer efficiency advantage over x86

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Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#291

Post by aurareturn »

txrx0000 wrote: post #198

It's not the ISA. Modern Macbooks are power-efficient because they have: - RAM on package - PMIC power delivery - Better power management by OS Geekerwan investigated this a while ago, see: https://www.youtube.com/watch?v=Z0tNtMwYrGA https://www.youtube.com/watch?v=b3FTtvPcc2s https://www.youtube.com/watch?v=ymoiWv9BF7Q Intel and AMD have implemented these improvements with Lunar Lake and Strix Halo. You can buy an x…

  Intel and AMD have implemented these improvements with Lunar Lake and Strix Halo. You can buy an x86 laptop with Macbook-like efficiency right now if you know which SoCs to pick.
M4 is about 3.6x more efficient than Strix Halo when under load.[0] On a daily basis, this difference can be more because Apple Silicon has true big.Little cores that send low priority tasks to the highly efficient small cores.

For Lunar Lake, base M4 is about 35% faster, 2x more efficient, and actually has a bigger die size than M4.[1] Intel is discontinuing the Lunar Lake line because it isn't profitable for them.

I'm not sure how you can claim "Mac-like efficiency".

[0]https://imgur.com/a/yvpEpKF

[1]https://www.notebookcheck.net/Intel-Lunar-Lake-CPU-analysis-...

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#292

Post by pezezin »

camel-cdr wrote: post #273
markfeathers wrote: post #203

Earlier quoted context omitted.

Check out ARM SBSA / SBBR which seems aimed at solving most of these issues. https://en.wikipedia.org/wiki/Server_Base_System_Architectur... I'm hopeful RISCV comes up with something similar.

https://github.com/riscv-non-isa/riscv-server-platform/blob/...

But those initiatives are focused on servers.

What about desktops and laptops? Cellphones? SBC like the Raspberry Pi? That is my concern.

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#293

Post by mrheosuper »

Teknoman117 wrote: post #185
pezezin wrote: post #178

After playing around with some ARM hardware I have to say that I don't care whether ARM is more efficient or not as long as the boot process remains the clusterfuck that it is today. IMHO the major win of the IBM PC platform is that it standardized the boot process from the very beginning, first with the BIOS and later with UEFI, so you can grab any random ISO for any random OS and it will work. Meanwhile in the ARM…

ARM systems that support UEFI are pretty fun to work with. Then there's everything else. Anytime I hear the phrase "vendor kernel" I know I'm in for an experience...

Fun Fact: Your Qualcomm based Phone may already use UEFI.

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#294

Post by Ianjit »

exmadscientist wrote: post #2

This is an entirely uncontroversial take among experts in the space. x86 is an old CISC-y hot mess. RISC-V is a new-school hyper-academic hot mess. Recent ARM is actually pretty good. And none of it matters, because the uncore and the fabrication details (in particular, whether things have been tuned to run full speed demon or full power sipper) completely dominate the ISA. In the past x86 didn't dominate in low powe…

This paper is great:

"Our methodical investigation demonstrates the role of ISA in modern microprocessors’ performance and energy efficiency. We find that ARM, MIPS, and x86 processors are simply engineering design points optimized for different levels of performance, and there is nothing fundamentally more energy efficient in one ISA class or the other. The ISA being RISC or CISC seems irrelevant."

https://dl.acm.org/doi/10.1145/2699682 https://abdullahyildiz.github.io/files/isa_wars.pdf

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#295

Post by mojuba »

exmadscientist wrote: post #247
jorvi wrote: post #224

Earlier quoted context omitted.

Nice followup to your link: https://chipsandcheese.com/p/arm-or-x86-isa-doesnt-matter . Personally I do not entirely buy it. Intel and AMD have had plenty of years to catch up to Apple's M-architecture and they still aren't able to touch it in efficiency. The PC Snapdragon chips AFAIK also offer better performance-per-watt than AMD or Intel, with laptops offering them often having 10-30% longer battery life at simila…

Yes, Intel/AMD cannot match Apple in efficiency. But Apple cannot beat Intel/AMD in single-thread performance. (Apple marketing works very hard to convince people otherwise, but don't fall for it.) Apple gets very, very close, but they just don't get there. (As well, you might say they get close enough for practical matters; that might be true, but it's not the question here.) That gap, however small it might be for…

> Apple has a max-efficiency design that's excellent for personal computing. Intel/AMD have aging max-performance designs that do beat Apple at absolute peak...

Can you explain then, how come switching from Intel MBP to Apple Silicon MBP feels like literally everything is 3x faster, the laptop barely heats up at peak load, and you never hear the fans? Going back to my Intel MBP is like going back to stone age computing.

In other words if Intel is so good, why is it... so bad? I genuinely don't understand. Keep in mind though, I'm not comparing an Intel gaming computer to a laptop, let's compare oranges to oranges.

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#297

Post by aurareturn »

hereme888 wrote: post #103

I was just window-shopping laptops this morning, and realized ARM-based doesn't necessarily hold battery life advantages.

They actually do. Qualcomm matches Intel's best battery life but gives you more performance. Apple exceeds the best x86 performance and battery life by a large margin.

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#298

Post by christkv »

torginus wrote: post #289
formerly_proven wrote: post #287

Earlier quoted context omitted.

> M-series chips have closely integrated RAM right next to the CPU, while AMD makes do with standard DDR5 far away from the CPU, which leads to a huge latency increase 2/3rds the speed of light must be very slow over there

I mean at 2GHz, and 2/3c, the signal travels about 10cm in 1 clock cycle. So it's not negligible, but I suspect it has much more to do with signal integrity and the transmission line characteristics of the data bus. I think since on mobile CPUs, the RAM sits right on top of the SoC, very likely the CPUs are designed with a low RAM latency in mind.

I think the m chips have much wider databus so bandwith is much higher as well as lower latency?

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#299

Post by yvdriess »

exmadscientist wrote: post #254
nerpderp82 wrote: post #228

Earlier quoted context omitted.

Isn't that still true for high perf chips? We don't have ways to use all those transistors so we make larger and larger caches.

Max-performance chips even introduce dead dummy transistors ("dark silicon") to provide a bit of heat sinking capability. Having transistors that are sometimes-but-rarely useful is no problem whatsoever for modern processes.

AFAIK the dark silicon term is specifically those transistors not always powered on. Doping the Si substrate to turn it into transistors is not going to change the heat profile, so I don't think dummy transistors are added on purpose for heat management. Happy to be proven wrong though.

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#300

Post by aurareturn »

bryanlarsen wrote: post #53
x0x0 wrote: post #50

Earlier quoted context omitted.

> That's not mostly because of a better ISA Genuinely asking -- what is it due to? Because like the person you're replying to, the m* processors are simply better: desktop-class perf on battery that hangs with chips with 250 watt TDP. I have to assume that amd and intel would like similar chips, so why don't they have them if not due to the instruction set? And AMD is using TSMC, so that can't be the difference.

What's it due to? At least this, probably more. - more advanced silicon architecture. Apple spends billions to get access to the latest generation a couple of years before AMD. - world class team, with ~25 years of experience building high speed low power chips. (Apple bought PA Semi to make these chips, which was originally the team that build the DEC StrongARM). And then paid & treated them properly, unlike Intel &…

  - a die budget to spend transistors for performance: the M chips are generally quite large compared to the competition
This is a myth. Apple chips are no bigger than the competition. For example, base M4 is smaller than Lunar Lake but is more efficient and 35% faster. M4 Pro is smaller than Strix Halo by a large margin but generally matches/exceeds the performance. Only the M4 Max is very large but it has no equivalent in the x86 world.
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