PS3 vs X360: Apples to Apples high level comparison...

Curious, who's "we"? B3D or...?

Anyway, just stating the obvious but those comparison's would be for a SM3.0 and SM2.0 architecture's and even more disparity...

So...

http://www.beyond3d.com/forum/viewtopic.php?t=13470

So...you've read the 'leak' wrong. It seems 'Billions' and 'cycles' and 'seconds' and 'numbers' are being confused...

What makes this more frustrating is that we've discussed these leaks many times in the other threads...

See above. That's a peak 'component' operation and NOT a 'shader' operation as mentioned earlier.

Please read my first post on the first page...

If you have, then it would be obvious that, CELL + RSX ~ 100 Billion shader operations per second.

And your quoting ONLY the Xenos GPU ~ 120 Billion shader operation per second ??

Lets keep this logical here...

 

If you've read the first post in this thread then you'd know that,

I'm trying to put perspective to these numbers from *both* sides. The 'peak' metrics have been derived on the first page and are valid for both as they have been consistently derived. So when some random 'numbers' come along from different, conflicting sources, pulling numbers out of context, there's some reference and a persepective. I've made clear they are 'peak' numbers and as close to an apples to apples comparison as you can get with the info we have from *offcial* docs from E3 PR.

This is essentially no different that putting the *offcial*, released spec metrics side by side. At least it has context and discussion in this thread.

And NOBODY has *real* world numbers. My point? FACTS not BS that's been flying round recently. Even if these facts are *purely* theoretical but nevertheless can be derived logically.

I've read some threads recently with people STILL crying foul at PS2 specs and yet conveniently forgetting to cry foul at XBOX specs and vice-versa. I smell fanb**s...

As I've just mentioned above, I'm after FACTS, be they theoretical or not but nevertheless authentic and not conflicting. Once these FACTS can be agreed on, then we can have sensisble discussions on whether they can be realisied or not or how realistic they can be or where potential weaknesses may lie. But unless that's agreed on, all we'll see are pointless, WRONG numbers spreading misinformation...

I don't care if technology is from ATI, nVIdia, Sony, MS, Nintendo or ACME...I care about interesting technology no matter who it's from. If the PR can't agree on consistency, then surely so called *smart* people on this forum can?

Have you read my derivations of the 'peak' numbers on the first page? If you can dispute them then please feel free as I want FACTS that can be consistently and independently derived from *offcial* info. I've used a consistent method that's held solid so far with *official* numbers. It's explaind all the other, conflicting numbers, including yours. If you can't accept/dispute those numbers then I've learnt something new today...

 

Let see...128 * 0.4 GHz ~ 51.2 GSops/sec

It's another component operation specific to pixels as I've already pointed out to you earlier in the thread with your 'page 3' reference. And if your going to use 'components' again, you've missed out the 'vertices' too for the total...

RSX ~ 136 shader ops per second ~ 136 *0.55 ~ 74.8 GSops/sec

Considering you've also missed out 'vertex' ops too from the '51.2 GSop', it's nothing near "half" of what was claimed and would infact be similar.

Perhaps you should try disputing my numbers on the first page instead of clutching at straws and throwing random numbers into the mix. But it doesn't really matter now because you've answered my question from my previous post....

From papers I've read, they suggest nVidia would move to a complete MIMD architecture. Also for Xenos, MIMD would suit it's GPGPU nature and would make sense.

Yep. But we have no low level details for RSX yet...they could still share similarities...

Been discussed to death on these forums...but I'm pretty clear on them...

I suggest you read/understand the whole thread first before making any further ignorant comments!

 

That metric represents exactly for Xenos, what it represents for RSX. You will find this in the Xenon 'leak' and my calculations/links on the first page, i.e..

Or

RSX ~ 136 shop/cycle
Xenos ~ 96 shop/cycle

These numbers/ metrics on there own are meaningless without further parameters. But both numbers also cross-reference with other metrics that I calculated on the first page without any conflicts. So they are consistent but need further analysis.

All this is essentially telling us (with the per CYCLE) is the number of execution units that run shaders, i.e. the number of shader execution units. It is not telling us the amount of work/computation being done per clock cycle nor the precision of the data being worked on.

E.g. it's not differentiating between 1-way, 2-way, 3-way or 4-way execution units. i.e. all of those shops/cycle can be from 136 scalar units or 136 vector units or a combination. Also these vector units can be vec(2-4) units! So we can't go into any further detail without further information.

However, from *official* MS spec from xbox.com,

Dave also mentions that they are 48 5D ALUs,

http://www.beyond3d.com/forum/viewtopic.php?p=526112#526112

The 'leak' above also mentions the 48 ALUs consisting of a vector + scalar unit,

===> Xenos> 48 vec4 + 48 scalar units> 96 Shop/cycle

The 4-way vector components of vec4 units are not included in the definition.

===> RSX> x + y units ~ 136 Shop/cycle*

* we need more info to determine more detail...and this is deduced from the DOT products information below.

From this information, we get, 24+10~ 34 Dot products per cycle ~ 18.7 GDot/sec*

*Vec4 unit is assumed to provide a 1 Dot/cycle and this means Dot product per cycle is an 'integer' number, e.g.. 34 Dot/cycle.


And more importantly, falls way short of the claimed CELL+RSX ~ 51 GDot/sec

Taking the contribution of DOT products from CELL, either from 7SPUs or 7SPUs+1VMX, we get,

RSX ~ 25.4 OR 28.6 GDot/sec

Which one is accurate?

25.4/0.55 GHz ~ 46.18 Dot product/Cycle?

or

28.6/0.55 GHz ~ 52 Dot product/Cycle?

The 46.18 Dot/cycle is rejected in favor of the 52 Dot/Cycle because it's not an 'integer' from above assumption.

From our earlier definition of a Shop/cycle, this then suggests 52 Vec4 units contribute to RSX's 136 Shops/cycle.

RSX~ 52 Vec4 units + 84 units not contributing DOT products.

http://www.beyond3d.com/forum/viewtopic.php?t=23228&start=0

http://www.beyond3d.com/forum/viewtopic.php?p=531473#531473

===>RSX~ 28.6 GDot/sec

Jawed-RSX'~ 18.7 GDot/sec is way short of my (Jaws*) RSX~ 28.6 GDot/sec and does not have enough Dot product computation to match the CELL+RSX claim. Therefore 18.7 GDot/sec and it's pipeline arrangement is unlikely.

* Yes, as if we don't have enough confusion, Jaws and Jawed is now officially confusing the shit out of me too(Jaws)!

From the above definition of a Shader operation, we don't include these metrics in Shop/cycle numbers. However, more than likely, these metrics have been included in the 'total system TFLOP' metric.

The 48 GShop/sec is used for Xenos here and I've cross-referenced that for valididty in my calculations for 96 Shop/cycle on the first page.

The 120 GShop/sec for Xenos is greater than BOTH CELL+RSX ~ 100 GShop/sec. We can reject the 120 GShop/sec number for Xenos here for being inconsistent. Even though that '120' number is a valid number, the 'unit' of the metric is not consistent. It would be more accurate to call it Xenos~ 120 Billion component (5D) operations per second and leave out 'shader' from the metric. And also, 120*2FMADD ~ 240 GFlop/sec, (32bit because of SM3.0).

If it's not obvious still, it's Xenos ~ 48 GShop/sec from *offcial* spec. doc.!

See above. You have to use consistent units of measurement when comparing throughout.

Taking this consistency, the following was derived,

RSX ~ 136 Shop/cycle ~ 52 Vec4 units + 84 units NOT contributing Dot products.

Xenos ~ 96 Shop/cycle ~ 48 Vec4 + 48 Scalar units.

Those 84 units for RSX can ALL be scalar for all we know or ALL be Vec3. So the measure of computation performed per cycle can vary. In that sense the aforementioned, 'component operation per cycle' metric will give more detail. But we don't have that for BOTH systems.




From what I've derived above,

RSX ~ 136 Shop/cycle ~ 52 Vec4 units + 84 units NOT contributing Dot products.

I'd be guessing now on the following, usually, scalar units are paired with Vec units so,

RSX ~ 136 Shop/cycle ~ 52 Vec4 + 52 Scalar + 32 Other units

32 Pixel Shaders ~ 32 Vec4 + 32 Scalar + 32 Other units*
20 Vertex Shaders ~ 20 Vec4 + 20 Scalar

*Other units can be Vec3 or Scalar etc...

Looking at that RSX image above, I don't think we can extrapolate pipelines and ISA from what we know of NV40 to RSX, any more than what we know of R420 to Xenos. In addition both Xenos and RSX are likely to have all their 'legacy' PC logic removed for consoles. E.g. SM1.0, SM2.0, etc. as they don't need to support the extra code paths like PC games. On second thoughts, not sure about Xenos now with B/C with Xbox-NV2a and PC games with XNA?

In any case, both Xenos and RSX will have assembly level, to-the-metal access on both consoles, irrespective of whether Xenos uses SM3+ or RSX uses OpenGL|ES.

Looking at the Xenon 'leak' text above, it suggests that one Xenos ALU ~ vec4 + Scalar, and those ALUs can dual issue to a Vec4 and a scalar unit. So,

Xenos ~ each ALUs(vec4+ scalar) can dual issue per cycle
48*2~ 96 instructions per cycle
96*0.5 Ghz ~ 48 Billion INSTRUCTIONS per second*

* Not SHADER ops per second and so another number to get confused with! I'll stop right here!