I want to measure the device how I use it. Race-to-sleep and power states are integral to CPU design.
Yes they are, but only one of those is at all affected by the choice of ISA. If modern AMD chips are better at race-to-sleep than an Apple M1 and still get worse battery life then the problem is clearly not x86-64.
Does anyone care about blaming / lauding an ISA without any connection to the actual devices that people use?
Performance and battery life are lived experiences. There’s probably some theoretical hyper optimization where 6502 ISA is just as good as ARM, but does it matter?
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…
I remember reading this Jim Keller interview: https://web.archive.org/web/20210622080634/https://www.anand... Basically the gist of it is that the difference between ARM/x86 mostly boils down to instruction decode, and: - Most instructions end up being simple load/store/conditional branch etc. on both architectures, where there's literally no difference in encoding efficiency - Variable length instruction has pretty…
> fixed-length instructions seem really nice when you're building little baby computers, but if you're building a really big computer, to predict or to figure out where all the instructions are, it isn't dominating the die. So it doesn't matter that much.
What if that core isn’t free? What if it’s not going to be free for a long time? That could be a recipe for random long stalls for some processes.
> What if that core isn’t free Just context switch it, like how you run 2 programs with single core cpu
It's correct to point out that you could end up in a situation where your "big" cores are all heavily loaded and your "small" cores with less instructions are all idle. That's unavoidable if your whole workload needs the AVX512 instructions or whatever, but it could be catastrophic if your OS just mistakenly thinks it does. But that doesn't seem unavoidable; see my comments further down the thread.
I suspect the throttling behavior has to more do with the power settings used during testing or OEM tuning on specific models. https://www.youtube.com/watch?v=ymoiWv9BF7Q In this video, they show the perf/watt curves at 8:30. And they show the on-battery vs on-wall performance at 18:35 across a wide variety of benchmarks, not just Geekbench. They used a Lenovo YOGA Air 15 on Window 11's "Balanced" power plan for thei…
Reviewers always use max performance setting for benchmarks and then max battery life for battery tests. That's how people get tricked. When they actually buy the laptop and use it for themselves, they complain that it's slow when on battery life or hot/loud when plugged in.
They're not trying to trick you. In fact when they were measuring perf/watt, the Lunar Lake chip was disadvantaged against the Apple M-series because they had to run the SPEC 2017 tests on Ubuntu for the Lunar Lake chip, which has poorer tuning for it compared to Windows 11. You can see a footnote saying the compilation environment was Ubuntu 24.04 LTS on the bottom left corner of the frame when they show the perf/watt graphs.
There are two separate issues here. Can an x86 be made nearly as efficient as an ARM chip with unbounded effort? Sure. But it's a lot easier to make a competent ARM design than a competent x86 design because there's so much more to the later and the front end has to be a lot more complicated to deal with the unsynchronized encoding.
He said "per watt", that's still true. You just talked about max throughput, which no one is discussing.
It's not, because Apple purposefully lied on their marketing material. Letting a 3090 go on full blast brings it pretty much in line in perf/watt. Your 3090 will not massively thermal throttle after 30 minutes either, but the M1 Ultra will. So, yes, if you want to look good on pointless benchmarks, a M1 ultra ran for 1 minute is more efficient than a downclocked 3090.
How do you think Nvidia got Samsung’s 8nm process to be just as power efficient as TSMC’s 5nm node?
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…
> x86 didn't dominate in low power because Intel had the resources to care but never did Remember Atom tablets (and how they sucked)?
IIRC Intel hobbled early Atom with an ancient process node for the chipsets which actually made up most of the idle power usage. It was pretty clear that both Microsoft and Intel wanted this product category to go away or at least be totally relegated to bottom tier lest it cannibalize their higher margin businesses. And then of course Apple and Android came along and did just that anyway.
Why would they? They are dominated by gaming benchmarks in a way Apple isn't. For decades it was not efficiency but raw performance, 50% more power usage for 10% more performance was ok. "The same goes for GPUs, where Apple's M1 GPU completely smoked an RTX3090 in performance-per-watt" Gamers are not interested in performance-per-watt but fps-per-$. If some behavior looks strange to you, most probably you don't under…
> Gamers are not interested in performance-per-watt but fps-per-$. I game a decent amount on handheld mode for the switch. Like tens of millions of others.
I game a decent amount on table top games. Like tens of millions of others.