AMD: RDNA 3 Speculation, Rumours and Discussion

Very different things to ever be mentioned in the same sentence.

 

ARM isn't interesting. It's the CPUs (and now GPUs) designed by Apple's internal silicon design team that are causing jaws to hit the floor.

The writing is on the wall, the benchmarks are in, and products are actually in consumers' hands. The performance-per-watt and performance-per-core of Apple's chips are astonishing, even when running x86 apps through an emulation layer.

?
Their transition is going according to plan. I believe Apple stated that by the end of 2021, their consumer Macs will all be on Apple Silicon. So far they've held their end of the bargain:
MacBook Air
MacBook Pro 13"
Mac mini
iMac (24" replacing the 21.5")
are all currently on Apple Silicon.

The only consumer class Macs that need the Apple Silicon treatment are:
MacBook Pro 16"
iMac (27")

Mac Pro will of course need some customised silicon -- most likely because having only integrated RAM would be untenable for the market which the Mac Pro addresses. I suspect we may see an Apple Silicon for the Mac Pro which resembles Sapphire Rapids: integrated cache/memory similar to HBM, backed by access to external DRAM. This chip will also need a truckload of PCIE lanes for expansion cards and Thunderbolt.

Few chips could ever be as disappointing as R600. Vega comes close though.

 

Hey we still have PVC to laugh at.
laughs

 

M1 and other Apple CPUs aren't "good" because they are ARM ISA. It's simply good and strong CPUs that happen to use ARM ISA, the M1 is proving that it's possible and someone is actually succeeding in leaving behind all the x86 legacy (remembering to be fair that Apple in the fortunate position that allows this).
It's not that ARM is "the way", more that's an viable alternative. There are other makes betting on ARM CPUs and soon x86 may lose it's supremacy in the marketing. How long until Intel and AMD start making ARM CPUs to not lose market share? And when that happens how long will it take to x86 become niche?

 

Why yes aarch64 toddlers are insufferable why do you ask?

Wut.
Even the best reference ARM core can be at best called a bad Zen3.

wut

how?

You're a fuckton years late since Seattle 'shipped' like 5 years ago.

major hopium moment

 

Yeah that's expected though given the rasterizer and triangle setup isn't the bottleneck the vast majority of the time. Navi 22 is still doing 2 tris per clock at a very high clock speed which is plenty geometry crunching power. It's a mystery why Nvidia continues to scale up their tessellation and triangle throughput. GA102 has 42 primitive setup units and 7 rasterizers while Navi 21 does just fine with only 4 of each.

 

Maybe from pure highend gamers point of view and when limiting "Vega" to mean only Vega 10, buit that's the only view where Vega might be considered even "close" to R600.

 

Ok, I got you. Why limit the conversation to just pixel shaders though? AMD's description of 64-item "wavefronts" appears to apply to compute workloads as well.

Locality doesn't seem to be a major motivating factor to keep it on the same SIMD as you get much of the same benefits as long as you're on the same CU. AMDs whitepaper only has this to say on the matter: "While the RDNA architecture is optimized for wave32, the existing wave64 mode can be more effective for some applications.". They don't mention which applications benefit from wave64.

Is it important that it's one hardware thread vs two? I guess my only point is that from a software perspective it doesn't matter.

Yep, that's the million dollar question. Does a big fat WGP scale up everything or just the SIMDs and cache.

 

One major caveat of this 2.5X~3X raster scaling is that 1440p and lower is going to irrelevant, our current CPUs are not strong enough to produce, a 3090 is already CPU limited at 1440p, and 4K is going to be CPU limited in a significant way as well.

 

On last gen games sure. Current gen console games targeting upscaled 4K at 30fps should take advantage of the extra horsepower on PCs shooting for native 4K at 120fps+.

 

Perhaps the die space/power requirements are small enough that they don’t deem it worthwhile to change the SM structure yet.

 

Anybody can answer me the question about the imbalance of rasterizer and Scan Converter?

My second question is that also the Frontend is a black box for me. In driver you find always the hint that you have 4 Rasterizer but 8 Scan Converter. So Scan Converter is the main Part which transforms Polygons into pixels. So when 1 Polygon comes from Rasterizer but you have 2 Scan Converter, 1 Scan Converter is running empty?[

 

It would run empty on polygon covering less pixels than one converter can generate.

 

Just in time for Zen4 V-cache CPUs!

 

Raytracing is easily scalable, PCs won't have any issues in applying all the performance they have. And once AMD will get their RT up to speed they'll begin to promote it's heavier usage in PC versions of multiplatform titles too. So I wouldn't worry about the overabundance of GPU power really.

 

I meant the OC limit in the Wattman, not the stock memory clocks. Of course, it's possble to check how how the GPU scales in supposedly memory-bound scenarios by simply decreasing the core clocks, but it might be confounded by things like some parts of the chip not really scaling with clocks and so on. So that's why I thought memory OC is the best way to check it, although IC and some form of in-built error correction (as far as I understood) makes this hard to gauge.

 

Just thought about this right before.
AMD could patch custom traversal shaders into specific per game driver updates.
Not what i want, not sure how much sense it makes, but there are options in theory.

 

You mean higher res gfx needs more CPU power up to the point the CPU throttles?
Which gfx CPU workloads depend on resolution? Animation stays the same, culling (if still on CPU) should have no big effect either?

 

Have they the ressources to pull that out ? I imagine it takes time, tests, etc...