[Geo]

Well then, finally put that one to bed, R600 it is.

http://www.xbitlabs.com/news/video/d...525104243.html

[trinibwoy]

Mr. Huddy said that Xbox 360 game console, which sports developed by ATI Xenos graphics core with unified shader architecture and 48 shader processors, loses 20% to 25% performance in pixel-shader limited games, when its graphics chip is configured as non-unified, e.g.,16 processors work strictly on vertex shaders, whereas 32 are assigned for pixel shaders.

I'm assuming that those numbers don't tell us much. Performance on a unified architecture after dedicating flexible units to specific tasks can't really be used as an accurate indicator of non-unified performance with a similar configuration (16/32).

[TurnDragoZeroV2G]

R600... heh. Needs to get me some of that. And Conroe, I'm thinking, at this point.

On a side note, if we can take the 20-25% losses on Xenos going from dynamic allocation to fixed 32/16 ratio to be accurate and realistic... then that's pretty impressive. Of course, he does have a job to do at the same time.

[tEd]

Well i expect the next nvidia chip to also be the fastest dx9 chip they've ever build.

[Geo]

Huddy using a comparison on Xenos of 32/16 (2/1) is interesting.

Are they back to claiming 16 shaders for R580 then? Because if not, 48/8 is obviously much higher than 2/1.

[SugarCoat]

R600 series, how many times do i have to say it!

[nelg]

This was very interesting (if true).

Mr. Huddy said that Xbox 360 game console, which sports developed by ATI Xenos graphics core with unified shader architecture and 48 shader processors, loses 20% to 25% performance in pixel-shader limited games, when its graphics chip is configured as non-unified, e.g.,16 processors work strictly on vertex shaders, whereas 32 are assigned for pixel shaders.

[Geo]

Originally Posted by SugarCoat

R600 series, how many times do i have to say it!

And as soon as you finally admit you've been a paid ATI employee all along, then we'll take it as official!

I keed.

[Jawed]

Release the damn thing already.

Getting seriously bored...

Jawed

[JHoxley]

Is R600 a D3D10 part or not?

My vague understanding was that Nvidia's G80 and ATI's R600 were the next-gen/D3D10 parts... but that linked article keeps on referring it to a DX9 part?

Cheers,
Jack

[Dave Baumann]

Yes, R600 is DX10 based (this article, I believe, was formed from an initial DX10 breifing that ATI are doing), however, the reality is that R600 and G80 will see far more DX9 code than they will DX10, so they have to be consumate DX9 performers as well as having DX10 capabilities.

[eSa]

Additionally, ATI says its first DirectX 10 graphics processor – code-named R600 – will have unified shader micro-architecture, which will allow to boost performance even further compared to currently existing micro-architectures and . The performance improvements are conditioned by a special built-in arbiter processor, which will “tailor” rendering of every frame across the 64 unified shader pipelines. Such an approach, according to ATI, allows to utilize all execution engines within the chip, while in traditional architectures – where pixel shaders and vertex shaders are calculated by dedicated units – some of the arithmetic processors may stand idle waiting for others to complete their tasks.

Hmm !!??? Where that 64 pipes comes from ??! Actual confirmation from ATI !?!?


Edit; Quote is from this article:

http://www.xbitlabs.com/news/video/d...525104034.html

[Chalnoth]

Originally Posted by eSa

Hmm !!??? Where that 64 pipes comes from ??!

64 is about right for the R600. Bear in mind that the R580 has 48 pixel shader "piplines" alone. These pipelines individually don't do as much as nVidia's pipelines on the G7x, however, and the number of texture units is probably only going to be 16-32.

It remains to be seen how well this will compare to nVidia's offering, about which we know nearly nothing (except that from their public statements, it seems unlikely to be a unified architecture).

[Geo]

The initial article from today says:

according to sources familiar with the plans of ATI Technologies as well as some media reports, ATI R600 will have 64 unified shader processors – an unprecedented number so far, 16 texture units – inline with today’s GPUs, clock-speed beyond 650MHz and support for high-speed GDDR4 memory controller.

So he may have just "assumed to be in evidence" his initial report.

I'm guessing 64 is the minimum we'd be looking at, or you might have scenarios where it couldn't hand R580 the licking you would want it to be able to do.

Could it be more than that? Dunno.

[Chalnoth]

Originally Posted by geo

I'm guessing 64 is the minimum we'd be looking at, or you might have scenarios where it couldn't hand R580 the licking you would want it to be able to do.

Could it be more than that? Dunno.

Right. It really depends upon how much logic they have to add just to implement the unification. If not much, and if they're producing it on a smaller process than the R580, then it could have significantly more pipelines.

If, however, it takes quite a bit more logic, and if they're still doing it on 90nm, or even just 80nm (which isn't much smaller), then 64 seems more likely (less is possible, but, as you said, the performance wouldn't be there, and thus such a situation seems unlikely).

Edit:
Since the current architecture seems to be 70% along the road to unification already, I actually suspect it won't take that many transistors. But just bear in mind that nVidia is currently sitting pretty with an architecture that only requires ~55% the die area of ATI's, and thus can add a whole lot more core logic before even reaching parity on die size. Anyway, I think it's going to be a very interesting fall (or perhaps early next year, if we're unlucky).

[Jawed]

I'm holding out for 96 Xenos style pipes and 32 TMU pipes. Gotta keep that 3:1 ratio and have some use for 100GB/s of bandwidth...

Jawed

[kyetech]

But I guess its no surprise theres not *that* many more pipes than the previous gen seeing as each pipe needs to be wider to support a SM4 pipeline no?

So really the budget is blown on redesign rather than additional pipes.

[Chalnoth]

I personally don't expect SM4 to require all that many more transistors over SM3. I think that the real reason we probably won't see more than 64 pipelines is that ATI's already got a big chip, and probably won't want to go any bigger for the next gen.

[kyetech]

Originally Posted by Chalnoth

I personally don't expect SM4 to require all that many more transistors over SM3. I think that the real reason we probably won't see more than 64 pipelines is that ATI's already got a big chip, and probably won't want to go any bigger for the next gen.

what about nvidia then?

[Chalnoth]

Originally Posted by kyetech

what about nvidia then?

Well, right. I expect them to have to spend quite a few more transistors to get branching performance up there. But they can grow their die size by a whole hell of a lot more, too (the GeForce 7900 GTX is just 55% the size of the Radeon X1900). So we'll have to wait and see.

[Jawed]

It's true that the new integer stuff in SM4 makes the pipeline more complex, but compared to R580 I dare say a Xenos pipeline is simpler (vec4 MAD + scalar special function versus vec4 MAD or vec3 + scalar special function PLUS vec4 ADD, the "mini-ALU").

So I think it's better to start with a Xenos pipeline and add integer functionality to it.

Jawed

[ShootMyMonkey]

Mr. Huddy said that Xbox 360 game console, which sports developed by ATI Xenos graphics core with unified shader architecture and 48 shader processors, loses 20% to 25% performance in pixel-shader limited games, when its graphics chip is configured as non-unified, e.g.,16 processors work strictly on vertex shaders, whereas 32 are assigned for pixel shaders.

I'm not sure this is really all that meaningful a statement. I mean, it's about a specific operational mode where 1/3 of the pipes are dedicated to vertex processing and the remaining 2/3 are dedicated to fragment processing. So... if you've got something that's pixel shader limited, and you reduce the maximum number of possible pixel shader units by 33%, you lose up to 25% of your performance... hmmmm... Nah, couldn't be.

Any examples of these particular pixel-shader limited games that gave them these results?

[Geo]

Someone in IRC speculated that this 2/1 test was probably driven by the granularlity they could mess with Xenos pipes, in groups of 16.

So, "when ps limited" is probably still valid, and that there is some significant advantage gained when that is true, is probably also still good. . . tho I think I'd take the actual percentages with a grain of salt.

[Chalnoth]

Originally Posted by ShootMyMonkey

I'm not sure this is really all that meaningful a statement. I mean, it's about a specific operational mode where 1/3 of the pipes are dedicated to vertex processing and the remaining 2/3 are dedicated to fragment processing. So... if you've got something that's pixel shader limited, and you reduce the maximum number of possible pixel shader units by 33%, you lose up to 25% of your performance... hmmmm... Nah, couldn't be.

I'd be rather surprised if the R600 ever made use of operation modes with fixed vertex/pixel ratios.

[Nelsieus]

Originally Posted by Dave Baumann

Yes, R600 is DX10 based (this article, I believe, was formed from an initial DX10 breifing that ATI are doing), however, the reality is that R600 and G80 will see far more DX9 code than they will DX10, so they have to be consumate DX9 performers as well as having DX10 capabilities.

Which is what most early Vista games will be. Primarily DX9 with DX10 features that gamers can enable granted they have a DX10 system. Or atleast that's my understanding of it.