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Snapdragon 8 Gen 1's iGPU: Adreno Gets Big

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Re: Snapdragon 8 Gen 1's iGPU: Adreno Gets Big

#41

Post by MindSpunk »

cubefox wrote: post #25

Any explanation why Qualcomm uses "tile based rendering" while Nvidia and AMD don't?

Because binning is expensive and increases the cost of processing geometry. It works on Mobile GPUs because bandwidth to main memory is very power hungry so eating the cost of binning is worth it when your power envelope is 5W and you just can't provide enough bandwidth to do immediate mode rasterization.

Desktop GPU's power and memory bandwidth budgets utterly dwarf what the mobile GPU has so paying the compute cost of binning doesn't make much sense because they can just throw more memory bandwidth and larger caches at it. Geometry binning and the kind of tiling mobile GPUs use has a lot of performance cliffs so it's generally avoided when you can. The second you go off the happy path of a tiler the performance drops like a rock, like in the compute example in the linked article. Desktop class GPUs can get most of the benefits of tiling by just letting their cache hierarchy do the 'tiling' for them to avoid hits to main memory.

Some desktop cards do some tiling work, probably to improve cache utilization, but they don't suffer from the same performance cliffs that mobile GPUs do.

Re: Snapdragon 8 Gen 1's iGPU: Adreno Gets Big

#42

Post by rbanffy »

Dalewyn wrote: post #37
rbanffy wrote: post #6

Earlier quoted context omitted.

I believe their biggest failure in branding is to not put out Raspberry Pi-like small boards for people to experiment. Anyone with a slight interest in computers knows an M3 is a beast and that an i3 is meh. Almost nobody outside Qualcomm knows why a Gen 8 N is better than an 800 and what the difference would be.

Intel Core i3 is to Apple M3, i5 is to M3 Pro, i7 is to M3 Max, and i9 is to M3 Ultra. If you think an i3 is "meh", you know nothing about computers. For the vast majority of users including gamers, an i3 is overkill.

I don't know which benchmarks you are using, but if you look at something like this:

https://www.cpubenchmark.net/laptop.html

you can see there is no i3 outperforming a base M3 and while some i7's and i9's (and Ryzen's) outperform even the top M3, it's only so because of core-count (at the expense of increased TDP and shorter battery life).

Re: Snapdragon 8 Gen 1's iGPU: Adreno Gets Big

#43

Post by rbanffy »

MikusR wrote: post #33
rbanffy wrote: post #6

Earlier quoted context omitted.

I believe their biggest failure in branding is to not put out Raspberry Pi-like small boards for people to experiment. Anyone with a slight interest in computers knows an M3 is a beast and that an i3 is meh. Almost nobody outside Qualcomm knows why a Gen 8 N is better than an 800 and what the difference would be.

The soc alone is 160+ dollars.

I didn't say the SBC needs to be ridiculously cheap as well, just to be competitive with others.

Re: Snapdragon 8 Gen 1's iGPU: Adreno Gets Big

#44

Post by my123 »

xlazom00 wrote: post #39
my123 wrote: post #35

Earlier quoted context omitted.

Qualcomm disables SVE (masked at the hypervisor level) on all their silicon. If you want SVE on a phone roday, your options are Tensor G3, Exynos 2200/2400 or MediaTek phones with ARMv9 CPUs. Or if you have hypervisor execution level code exec (including an unfused phone), you can patch up that limitation.

So I have this https://en.wikipedia.org/wiki/Windows_Dev_Kit_2023 And we can run ubuntu on that https://github.com/armbian/build There isn't any hypervisor running on that and still no SVE So any advice ?

This runs Cortex-X1C and A78C, which are of the generation _just_ before the one that got SVE

Re: Snapdragon 8 Gen 1's iGPU: Adreno Gets Big

#45

Post by Dalewyn »

rbanffy wrote: post #42
Dalewyn wrote: post #37

Earlier quoted context omitted.

Intel Core i3 is to Apple M3, i5 is to M3 Pro, i7 is to M3 Max, and i9 is to M3 Ultra. If you think an i3 is "meh", you know nothing about computers. For the vast majority of users including gamers, an i3 is overkill.

I don't know which benchmarks you are using, but if you look at something like this: https://www.cpubenchmark.net/laptop.html you can see there is no i3 outperforming a base M3 and while some i7's and i9's (and Ryzen's) outperform even the top M3, it's only so because of core-count (at the expense of increased TDP and shorter battery life).

I'm talking about their tiers as merchandise. i3 is to Ryzen 3 is to M* (eg: M1, M2, etc.). They are all the lowest tier of their respective premium class of merchandise.

And regardless of benchmarks, an i3 will overkill any workload the average man will ask of it. You do realize an i3 has 4 hyperthreaded cores these days?

Re: Snapdragon 8 Gen 1's iGPU: Adreno Gets Big

#47

Post by kbolino »

kllrnohj wrote: post #38
kbolino wrote: post #34

Earlier quoted context omitted.

If you can afford to render the entire screen, why would you tile? Tiling complicates certain kinds of shaders, tiles have to be stitched together to make the final image, and tiling redraws (different parts of) the same triangles multiple times. On a dedicated GPU with lots of memory bandwidth, there's probably no benefit (and maybe even some penalty) to use tiling with lower resolutions (e.g. 1080p). However, 4K re…

The output resolution doesn't matter. The reason you tile is to improve locality and thus have more cache hits. For mobile GPUs, the cache is literally a specific tile buffer, but for nvidia (who also do this) the cache is just L2. But by tiling the geometry, they spend more time in L2 and fewer times hitting DRAM. This is a performance and power win. The actual resolution is irrelevant as the tiles are very small, e…

It seems like nVidia's solution is actually different than the conventional tiling of PowerVR, though they are broadly similar and as you say address the main VRAM bandwidth issue by using smaller but faster cache.

I've watched parts of that video a couple of times, but I don't fully understand it. The best I can make of it is that PowerVR tiles everything at all levels of rendering, whereas nVidia's Maxwell (and other, more modern, desktop GPUs?) tiles only up to the point of rasterization. If I understand this correctly, it means that pixel shaders on mobile operate on a limited view (their tile, plus some margin?) while pixel shaders on desktop still operate across the entire screen. I don't know if this matters that much in practice, and the distinction seems to be motivated by patents (which may have expired by now?) rather than technical necessity or benefits.

Either way, given the massive importance of cache locality, what I originally said about tiled rendering offering no benefit at 1080p is indeed wrong. I think my understanding of GPUs is more than a decade out of date at this point. These problems used to be solved with more power and wider memory buses. That seems to have stopped scaling well over 10 years ago.

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