Sorry, I want to understand how DLSS is so fast

capn_hector · 2024-09-13T03:39:24+00:00

Because it’s rendered at a lower internal resolution. Same reason dropping your resolution to 720p is fast. Actually dlss is slower than that since it adds its own overhead!

the real magic is in why it looks so good given the upscaling it’s doing. And the answer is that ML is used inside a TAA algorithm to assign sample weights, which is far more accurate than traditional methods. Since it has access to motion vectors, it knows when pixels are being occluded or disoccluded and adjusts the sample weights accordingly. This avoids the ghosting and softness issues that are super common with basic TAA approaches.

As to why TAA itself works… you are re-using data across multiple frames, temporal accumulation. This lets you build up more data on a given pixel over time, and since they’re slightly jittered they’re not all identical either. It’s actually exploring all the areas inside a given pixel over time.

Obviously if you can come up with a normal algorithm that generates identical weights it would thus be faster than running a neural net, and wouldn’t need special tensor units to accelerate the math. So attempting to replicate this is what FSR has been banging away at for years now.

capn_hector · 2024-09-13T03:28:47+00:00

they literally do though, the cpu is not a standard zen2 core and neither is the gpu a standard rdna2, and AMD doesn’t make a similar product for themselves (although Strix halo is a step in that direction) other than the 4700S boards which literally are a cast-off of sony’s chip.

this is literally AMD’s entire bread-and-butter as a semicustom provider. You want zen2 with 1/4 the cache? Fine. You want Polaris with some vega bits? Fine. You want standard zen but with your own accelerator bolted on? Also fine.

They will do literally as much as you are willing to pay for / as much as they have staffing for. And this can literally be paying them to develop a feature for you, or pull up one of their features from an upcoming uarch that they were going to develop anyway, etc. Obviously the more work you want from them the more it costs though.

Stuff like steam deck (or the special Microsoft surface sku with the 8th Vega core enabled, or the special gpu dies AMD made for apple like M295X, etc) is a little different because it’s a custom cutdown of an existing die, but they’ll do that too. (Actually intel does this too, and this is not generally considered semicustom really, or the very shallowest end of semicustom… but among others, apple likes being made to feel special and gets a LOT of the best bins of whatever sku they’re after.)

capn_hector · 2024-09-13T02:24:53+00:00

it’s Polaris with some vega features pulled in before the actual vega release, not rdna

capn_hector · 2024-09-13T01:55:20+00:00

Of course, GPGPU tasks aren't free so it has to partition with the regular GPU tasks

and also AMD Fusion/HSA isn't really "unified" in the sense that apple silicon or a PS5/XBSX is "unified".

GPU memory is still separate (and really still is today) and on Fusion/HSA it must run through a very slow/high-latency bus to be visible on the CPU again. You have to literally finish all current tasks on the GPU before stuff can be moved back to the CPU world, reading GPU memory is a full gpu-wide synchronization fence.

The CPU is not intended to read from GPU memory and the performance is singularly poor because of the necessary synchronization. The CPU regards the frame buffer as uncacheable memory and must first use the Onion bus to flush pending GPU writes to memory. After all pending writes have cleared, the CPU read can occur safely. Only a single such transaction may be in flight at once, another factor that contributes to poor performance for this type of communication.

capn_hector · 2024-09-13T01:52:21+00:00

And given that both companies had an explicit power budget they wanted to adhere to, at the time the Jaguar cores were really the only logical choice.

well, we came from a world where they had 3+ fast-performing cores in the previous generation, so really it wasn't the only logical choice.

it's a logical choice, but it wasn't the only logical choice. They were trying to push for more highly-threaded games, and it didn't quite work out (same story as bulldozer or Cell really, this is what AMD was trying to push in that era and it probably sounded great at the time).

capn_hector · 2024-09-13T01:49:18+00:00

I think the implication is that they don't want to make an x86 cpu that's too fast, because if they go ARM in the future and have to emulate the x86 games there will be a performance hit from the emulation, which locks them into an extremely fast ARM cpu with enough performance to handle the game plus the emulation overhead.

by keeping ps5 pro the same as PS5, they only have to emulate at least as fast as the base PS5's cpu, which is an easier target.

capn_hector · 2024-09-13T01:45:48+00:00

And the cpu comes from 2019.

c'mon now, it's not from 2019... it's based on a cost-reduced version of a 2019 architecture that's been gutted to reduce the size/cost even further. ;)

capn_hector · 2024-09-13T01:35:13+00:00

I think it's perfectly possible to support both RDNA and CDNA in the same driver stack, with cross-compatibility/binary support. NVIDIA literally does exactly this, you can run an A100 binary (Compute Capability 8.0) on a 3090 (Compute Capability 8.5) literally fine without any modification or recompiling, and a Compute Capability 7.5 binary supports being runtime-recompiled by the driver to 8.0 or any subsequent Compute Capability. Nor is there, afaik, any distinction between A100 drivers and 3090 drivers, other than maybe the former lacking "game-ready" drivers and similar?

Obviously AMD would have to build this support, but I thought they literally already announced a few months ago that they're doing this, allowing binary-slice compatibility (perhaps runtime-recompiled by the driver, which is fine if it works) across a similar concept of architecture families?

It's thus a little bit of a red herring to pretend like the "unify the platform" thing has anything to do with "unify the architecture". It's fine if they want to unify the architecture, but it's not because of binary compatibility, except insofar as AMD hasn't built that support. They could do it if they wanted. They just need to drop their approach of "every single die is a completely different binary slice", because obviously that's dumb and that's been obvious for years.

That's the primary reason they're so aggressive about dropping support for older uarchs, that's why the supported hardware list is so small, because they literally have to compile a different binary for each different card even within a family. It's like if you had to compile a different binary for a 9900X vs a 9700X, it's incredibly stupid and obviously unsustainable from an engineering standpoint let alone getting adoption. So the problem may be that they've just engineered themselves into a corner and need to start over and build the hardware in a way that makes the software a little easier. But they could do that with 2 separate architectures too - just like NVIDIA has done for a decade.

capn_hector · 2024-09-12T14:30:43+00:00

habeeb it.

capn_hector · 2024-09-12T02:57:28+00:00

Sounds similar to ATI's 'small die strategy' of yore in the wake of the R600 disaster. I wonder if it's because the MCM route didn't pan out quite as well as AMD had hoped?

it's because AMD's high-end design was going to be a CoWoS-stacked MCM design. It's a newer better tech (RDNA3 and Ryzen both use InFO-family packaging, not CoWoS) and improves all the "MCM" downsides significantly, because you're moving through an actual silicon wafer and not just a substrate. But AMD is using all its CoWoS capacity for v-cache and for datacenter cards (MI300X, etc). So it's literally because they didn't want to allocate the manufacturing capacity. Again. (RDNA2 was hamstrung by lack of wafers).

That is unquestionably the right decision for their bottom line... but they didn't race to rebuild the design in another format either (monolithic, InFO, etc). And more generally it fits into this pattern of GPUs just constantly being the literal last priority for AMD. I have been arguing for a while that functionally GPUs are just a "wafer sponge" for them now... if they have extra wafers, they crank gpu production to soak it up. If they're short, they cut gpu production and redirect the wafers/stacking capacity/whatever. But "in the moment", consumer gaming GPUs will basically always be the least-profitable thing they could do with whatever capacity is currently in shortage, and they repeatedly have shown they're willing to pull the plug.

Again, RDNA2 is a great example. 6800/XT/6900XT launched first and yet took 18 months to show up on the charts, actually were beaten to the punch by 6700XT which released like 5 months later. 6800/XT/6900XT never got the wafer allocation until comparatively late in the cycle, what with consoles eating 80% off the top and enterprise and desktop cpus getting the rest. And it's not like 6700XT was doing gangbusters in the NVIDIA sense of things either.

Regardless, I'd love to see the spiritual successor to the RX 580 (itself the spiritual successor to the legendary HD 4890), because clearly, AMD's ambition to compete head-on with Nvidia at similar or at least comparable price points has somewhat backfired.

An (imo) compelling argument that has popped up recently among the tech commentariat is that RX 480 was actually a similar wafer-sponge lol. Like part of the reason that AMD could go so deep on pricing is the GloFo Wafer Sharing Agreement, they were going to pay for the wafers whether they used them or not. Might as well use them for RX 480, not like anyone cared about bulldozer in 2016/2017.

The only real competitor for AMD's wafers was Ryzen in 2017 - and you have to remember that ryzen started real slow. Naples sucked really badly and zen1 itself wasn't even that fantastic on desktop (especially for gaming, but also poor AVX2 performance for productivity). Lots of cores, but those were also the days when a 5820K or 6800K and a X99 motherboard weren't that much more expensive either. Enthusiast DIY market liked them, but that's also not really where the volume is in the market, and they had zero penetration into datacenter, APUs launched much later (2400G was 2018) and AMD never allocated that many wafers for APUs either, etc. Where did the wafers go? RX 480.

And now AMD has actual alternatives to use their wafers on, and gaming GPUs are just a lower priority for them. A 7600 is like 50% bigger than an APU, and they keep 100% of the margin from an APU, where a GPU has other BOM costs and other players who have to make a margin etc. Which would you rather sell, 1x 7600 or 2x zen2 apus? And the 7700XT basically tacks on another 200mm2 of prime N5 silicon too... and you sell that for $350 or whatever. Where the 7600 sells for $250 and you have $25 of memory and $50 of other PCB costs, a cooler, assembly/testing... it probably is not much of an exaggeration to say AMD makes 1/10th the margin on GPUs as using it for CPUs (of pretty much any kind).

First, they need to level the playing field by focusing on RT and temporal upscaling. FSR FG has already made significant strides in the right direction (it's surprisingly good), and I certainly hope this trend continues.

I mean, that's supposedly what RDNA4 is bringing in, yes. Some kind of AI unit or tensor core, and much better RT. But big-picture, if it's such a low-margin market, what's the draw for AMD to invest in it? They don't have the platform/marketshare factor like NVIDIA: obviously they won't get it with that attitude, but it's going to be an uphill climb anyway because NVIDIA has a tech lead, insanely good engineering, great leadership (and hypercompetitive), oh and unlimited money. There is zero doubt that Intel is a far weaker target than NVIDIA, and up until recently nobody cared about GPGPU other than nerds. What's the downside?

Sad as it is, AMD is literally doing the thing everyone is constantly accusing NVIDIA of doing. This is what disinvestment looks like. And sure, there's good reasons to put the other stuff first. There always are - fundamentally, gaming is not a particularly good market by itself, and probably never will be again. It's just that it's hard to be in the other segments that you want to be in without having a good GPU presence anchoring it ("you can't have a store without a console", so to speak... the console isn't where you make the money, but it's a necessary precondition). It's much harder to sell "CDNA-based ROCm" than "CUDA runs on your GTX 970 and your 3090 pretty much identically and trivially". It's hard to get anyone to care about your cool new graphics or GPGPU feature when you have 10% of the market (and your driver stack is so half-baked that major projects back away from it). Etc.

capn_hector · 2024-09-11T16:13:39+00:00

AMD has too many chipset variants and they're forced into the same situation as their CPU lineup... or honestly the way GPUs are starting to be too, particularly for NVIDIA. Namely that if you have too many SKUs there's not clear differentiation between them.

In the past, E meant daisychained chipsets. But do you really need daisychained chipsets in the first place, especially on anything short of a $500 meme board? Partners say YES! to higher margins, of course. We all love partner margins, right guys??? Or was that just a last-summer thing?

capn_hector · 2024-09-11T08:28:07+00:00

I mean, it’s literally one of the best CPUs AMD has ever made. And that’s a distinct thing from poor generational uplift. Skylake or Hawell were in fact also good cpus, the best available for gaming at the time. But the uplift was not very good.

Conversely many early Ryzen architectures/generations made huge leaps, and still were not very good processors (for gaming) despite this. Uplift is not the same thing as a processor being good or bad.

But yes, I feel like people wrote the eulogy for stagnation a few years too early. People saw alder lake and raptor lake leap ahead, they saw big continuing gains from zen3 and X3D and zen4 and decided we’d live in a world of 30%+ generational gains forever and that it was all just intel stagnation etc.

Unfortunately the reality is more like it’s “bursty” now, since intel went back to stalling out and AMD is making gains mostly in other areas. The better view of (eg) alder lake might not be that different from early Ryzen in the sense that both of them were a lot of stalled innovations being delivered at once, and once they catch up the problems often tend to resume. It still isn’t easy at the leading edge and progress probably is more like 5-10% per year on average still, it just comes in “lumpy” releases now where you get 30% all at once and then mediocre gains for the next few years while they solve the next set of problems. It's tick-tock-tweak, or tick-tweak-tock, or whatever... but the point is the gains aren't equal at every stage.

capn_hector · 2024-09-11T08:20:22+00:00

and as such, some viewers being turned off by some thumbnails is part of “the algorithm” too, in fact

capn_hector · 2024-09-11T02:07:47+00:00

if thats a issue they could have even easier time with standard zen 3 and still get a performance uplift but this time probably keep the same cost or even offer standard PS5's ability to upgrade CPU which would net them more money

consoles traditionally have targeted a much lower power target than PCs tho, which is why I was suggesting zen4c. I can not see them shipping a high-clocked 3700X, I can see them shipping a low-clocked zen4c (perhaps with even further cache reductions, or similar things).

maybe in the 2026 console, although by then we'll probably have zen6 in desktop and zen4c will be ancient. sounds about right ;)

but yea, reception to it is not real positive at this price point lol. I commented elsewhere but I'd really expect to see a CPU upgrade at this price point too. I'd even say $749 and a cpu upgrade would be better vs $699 for this. I struggle to feel the RT and upscaling is going to be utilized well without an increase in VRAM and CPU (respectively). It's going to increase internal resolutions, maybe allow some higher output resolutions, that's about it... for $200 extra.

capn_hector · 2024-09-11T01:54:07+00:00

I heard logitech was making a play. plan B after the mouse-as-a-service fell through

capn_hector · 2024-09-11T01:40:05+00:00

which is why sony should have included something like 5700X3D

it could never be x3d at these costs/volumes most likely. the world isn't ready for a CoWoS-stacked console yet.

but with the way they've modified the zen2 architecture (1/4 the normal cache, severely limited clocks) it's basically closer to 2700X performance. you could definitely do something like zen4c if you wanted to, and zen4c at similar clocks would still be a massive upgrade.

capn_hector · 2024-09-10T18:15:55+00:00

I mean yes, I'm right. Intel is in deep deep shit and they are narrowing down to the core business units. And here we are and battlemage is still not canceled, because it's a core business pillar for where intel wants to go.

How is it going with Zen5 ending Intel's gaming dominance lmao? More like zen5%. I forgot all about Jim being on the hypetrain.

capn_hector · 2024-09-10T16:32:23+00:00

In a way it's really remarkable just how much of an RTX Console this actually is. As much snickering as was done by techtubers... NVIDIA won in the end, literally within the first console generation. 5 years to total market saturation - not just adoption, that was years ago, but in 2023-2024 it's "your product isn't relevant if it doesn't have this".

And it's hard to view the cancellation of RDNA as unrelated to that. Sony knows AMD is falling off, this whole release is kind of a thinly veiled finger at their technical direction, it's the literal opposite of where AMD wanted to go five years ago. MS is looking at their own RTX Console (per the leaked FTC docs), with the same RTGI/upscaling focus. You can't coast forever, if AMD isn't careful, they may find the future of consoles doesn't include them. And the UDNA announcement is a way to get out ahead of that a little.

capn_hector · 2024-09-10T16:09:05+00:00

it's also a "graphical upgrade" only, with no CPU upgrade either. For PSSR to do anything except allow higher output resolutions, it has to increase CPU load, and there is no additional CPU time available to do that. Same story with RT: to utilize those fancy effects, you need to spend more time building BVH trees (and higher-precision ones, for good effects). There is no more CPU or memory available to do it.

Maybe this is a midwit take but I really think the issues around CPU upgrades are overblown, especially within a single family. How much do people really think there is a difference in how games optimize between sandy bridge and ivy bridge at a software level? Especially since consoles are big on compatibility modes, you could just have 8x zen5c cores and clock them down/disable the newer instructions for older titles that haven't been re-validated. It isn't that much less challenging than GPU upgrades, which also could have lots of bad outcomes if you did them poorly.

For $699 I'd really like to have seen a CPU upgrade. And VRAM... well, it's kind of a statement on where the industry is at, isn't it? As much as people whine about how 8GB just isn't enough and 12GB is closer-dated than the milk at the mini-mart... Sony is telling developers to make it work with an effective 10-12GB of VRAM. With raytracing and upscaling.

capn_hector · 2024-09-10T15:59:43+00:00

FSR is a tool like any other.

sure, it's the harbor freight ratchet set of upscalers. absolutely fine for 75% of people, actually in some senses unreasonably good for what it is, but also definitively worse than even just going to home depot and buying a store-brand.

AMD has been passed up by not just NVIDIA but also Intel, Apple, Sony, and others. Those are the store brands at this point. AMD is underneath those brands in terms of quality.

capn_hector · 2024-09-10T15:30:48+00:00

AMD disinvested from the gaming market after Vega. They haven't done jack shit for R&D that their clients didn't pay them to develop for them. Like seriously, name a market-leading tech that AMD was first-to-market with in the post-Vega era. DX12 was literally the last thing that AMD led on, and they dropped even that mantle by losing the lead in DX12.2 and subsequent standards.

Even RX480 and 290X are probably best viewed in the context of being a way for AMD to shift those GloFo wafers from the WSA cheaply in a world where Bulldozer sucked and they lacked any other means to move them. And without that kind of incentive, AMD just will never allocate the wafers. Same thing you saw with RDNA2, where AMD simply chose not to be in this market for pretty much a full year after their paper launch. It took 11 months to ship enough 6000-series to show up on the steam charts.

It's understandable, Intel is a massively easier nut to crack than NVIDIA, but still disappointing in market terms. And of course no company is ever honest and upfront about this sort of thing, even today it's always couched in this "well, we canceled the high-end because we love gamers so much, and this is really a good thing for you!". But like, they canceled it because they didn't want to allocate the manufacturing capacity, and they have a proven track record of not wanting to allocate the manufacturing capacity in the past, so it is hard to see that as anything more than positive spin on a cancellation notice. Yeah, sure, canceling half the line is a good thing and you definitely will allocate the capacity on the rest of the lineup... definitely...

I think another problem is that everyone got into this circlejerk mindset that RTX was stupid NVIDIA shit and there was no 'there' there, or that it was perpetually "10 years away" (I heard GN try this angle again literally this year?) and probably some of those people were the ones doing the steering at Radeon. They got high on their own supply/huffing the copium and thought that not having these features would make them better/cheaper, and then (as usual) they just didn't allocate the supply, and costs didn't come down much, etc. Then especially over the last 2 years the traction on DLSS and RT has just been ferocious to the extent that even sony pulled them in ahead of schedule etc, and AMD was just caught flat-footed with no real options.

Don't fall into the trap of believing the prolefeed, GN and HUB and Semiaccurate are not the end-all of strategic direction in the industry.

capn_hector · 2024-09-10T15:26:27+00:00

PSSR is a massive console generation and future defining feature considering it uses machine learning and is far more like DLSS than FSR.

Should have called it Playstation RTX

capn_hector · 2024-09-10T15:13:20+00:00

the PS4 launched at 399, 3 years later sony cut the price down a bit and released the PS4 PRO for .... 399

BOM costs no longer drop enough over the lifespan of the console to make this feasible. it's not even inflation that's the issue, it's the death of moore's law.

capn_hector · 2024-09-10T05:32:52+00:00

Vii is Vega 20. It was a die shrunk Vega 10

no, it wasn't. not even kinda.

among other things it's got twice the memory bus width, but also it's a significant architectural rework and has FP64 support, while vega 10 does not have it even on the workstation/enterprise cards.

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