R500 and Shader balancing

[DOGMA1138]

There had been some talk`s here about the R500, and that it`ll have 5 times the vertex and 9 times the pixel power`s of the R420.
so if it`ll have unified shaders, how come it`ll still have much better PS preformamce? shouldn`t the unified shader slove the PS/VS balancing issue?

 

[kyetech]

because, if its a unified 64 pipeline card, and the r420 had

16 fixed pixel pipes.
6 vertex shaders..

then

r500 has 64 / 16 more pixel pipes or : 4x more pixel pipes.
r500 has 64 / 6 more vertex pipes... or 10x more vertex power.

but only if you dedicate the entire card to one or other.

if both were even then you could say 32 of one and 32 of other.

I might be wrong.... I usually am... But thats what I think.

 

[DOGMA1138]

if i remember correctly it was 5 x VS power and 9 x PS power. if that`s the case then there something wrong with your formula. im looking for the origenal post to check the numbers again...

 

[akira888]

R500? You mean Xbox2 GPU?

The leaked diagram described a chip which had 8 pixel pipelines, 2 texture accesses (bilinear) per pipe per clock, 3 ALUs per pipe, and a maximum throughput of one vertex, one triangle, and two quads (one quad if using a floating point render target) per clock. And IIRC it could also run output 16 depth/stencil only pixels (4 quads) per clock a la NV3X.

Not including the "mini-ALUs" the R420 has 16 ALUs for fragment ops and 6 ALUs for vertex ops compared to 24 total in R500, so I think 5X and 9X performance deltas might be a bit overoptimistic. But then again this is a fixed platform which developers can optimize exclusively for and therefore efficency should be much higher than on PC (there are also some rumors concerning double pumped arithmetic units).

 

[DOGMA1138]

that`s all?!
and where do the unified pipe-line get in all that?

 

[loekf2]

that`s all?!
and where do the unified pipe-line get in all that?

Correct. I guess Dave Baumann is now screaming and yelling like crazy and almost capable of jumping out of the window ;-)

Okay, I've been brainwashed on this forum, but for last time:

R500 = unified shader architecture (maybe borrowed from R400, which even taped out before it got canned)
R520 = based on R3xx/R420 marchitecture, which means it's still a "conventional" design in DirectX 8.0/9.0 speak, so it has pixel shaders and vertex shaders.

 

[DOGMA1138]

yes, so we are back at square one.
i guess we`ll have to wait until the full xenon spec will leak out. grrr bloody NDA agrrements.

 

[Megadrive1988]

DOGMA1138 wrote:

There had been some talk`s here about the R500, and that it`ll have 5 times the vertex and 9 times the pixel power`s of the R420.

it (the R500 in Xbox2) was said to have *10* times the vertex/geometry performance and *4* times the pixel performance of R420 aka Radeon X800.

http://www.beyond3d.com/forum/viewtopic.php?t=18222
http://endian.net/details.asp?tag=atir500
http://www.xbitlabs.com/articles/editorial/print/news26_glance.html


with that said, I don't think that is exactly true. or if it is true (the 10x geometry performance) it would be only when R500 is dedicating all of ALUs / Pipelines / Unified Shaders towards geometry/vertex processing, and nothing or little left for pixel processing.

otherwise it could be construed that Xbox2 will push 5~6 billion verts per second (peak) compared to the 5~6 hundred million verts per second (peak) pushed by R420. which might be a little unrealistic.

 

[Mulciber]

because, if its a unified 64 pipeline card, and the r420 had

16 fixed pixel pipes.
6 vertex shaders..

then

r500 has 64 / 16 more pixel pipes or : 4x more pixel pipes.
r500 has 64 / 6 more vertex pipes... or 10x more vertex power.

but only if you dedicate the entire card to one or other.

if both were even then you could say 32 of one and 32 of other.

I might be wrong.... I usually am... But thats what I think.

or could be just 32 pipes with double the clockspeed of the r420...

 

[DOGMA1138]

DOGMA1138 wrote:

There had been some talk`s here about the R500, and that it`ll have 5 times the vertex and 9 times the pixel power`s of the R420.

it (the R500 in Xbox2) was said to have *10* times the vertex/geometry performance and *4* times the pixel performance of R420 aka Radeon X800.

http://www.beyond3d.com/forum/viewtopic.php?t=18222
http://endian.net/details.asp?tag=atir500
http://www.xbitlabs.com/articles/editorial/print/news26_glance.html


with that said, I don't think that is exactly true. or if it is true (the 10x geometry performance) it would be only when R500 is dedicating all of ALUs / Pipelines / Unified Shaders towards geometry/vertex processing, and nothing or little left for pixel processing.

otherwise it could be construed that Xbox2 will push 5~6 billion verts per second (peak) compared to the 5~6 hundred million verts per second (peak) pushed by R420. which might be a little unrealistic.

ok thanks couldn`t find it on my own.
any idea on when some confirmed spec will leak out?

 

[ZoinKs!]

Supposedly it'll be announced at CES this January. Hopefully we'll hear more firm details then.