It seems that some analysis overestimates UMA. It won't accelarate simple CPU performance and won't reduce RAM usage unless its data is also used on GPU.
Possibly is they also call stacked RAM as "UMA" rather than shared RAM between CPU and GPU?
What I find odd is how someone rushes out to "debunk" nearly everything Apple has said that they did to optimize the M1. It's clear the M1 is fast, so clearly some of the things they did to optimize it worked. Why Apple would lie about what those optimizations are is a head scratcher.
It strikes me as odd that so many people claim there is zero benefit. I'm left wondering if people think Apple is lying about all of the actual reasons the CPU is fast and have presented this as a smokescreen. Makes zero sense to me.
> Why Apple would lie about what those optimizations are is a head scratcher.
Indeed it is. But marketing isn't really known for being technically accurate, why would Apple's be any exception?
> It strikes me as odd that so many people claim there is zero benefit.
That's not the claim at all. The claim is that unified memory isn't new, and there's a decent chance you already had it. For example, every Macbook Air of the last few years has been unified memory. The M1's unified memory is therefore a continuation of the existing norms & not something different. The M1's IPC is something different. The M1's cache latency is something different. The M1's 8-wide decoder is something different. There's a lot about the M1 that's different. Unified memory just isn't one of them, and unified memory still just doesn't improve CPU performance. All those CPU benchmarks that M1 is tearing up? It'd put up identical scores without unified memory, since none of those benchmarks involve copying/moving data between the CPU and a non-CPU coprocessor like the GPU or neural processor.
> But marketing isn't really known for being technically accurate, why would Apple's be any exception?
The comments and emphasis about the benefits on unified memory come right out of Johny Srouji's mouth. Granted, everything Apple execs say is vetted by marketing and legal, but I can't see Srouji emphasizing a made-up marketing point as a weird red herring either.
As I mentioned above, someone on HN has "debunked" every single optimization Apple says they've done. But the numbers don't lie. Somewhere along the way, some of the "debunking" is full of shit. I'm guessing most of it is.
The simplest explanation is that Apple is being forthright here and people don't understand what they've done or how those optimizations work.
Possibly is they also call stacked RAM as "UMA" rather than shared RAM between CPU and GPU?