This is something I've wondered about. We all know the RSX doesn't quite match up the Xenos, given the fact that a lot of multiplatform titles tend to favour the 360 as far as things like graphics and frame-rate are concerned, although the disparity is becoming more and more diminished over time, as developers have learned to utilise the Cell properly. Now, I'm wondering how much of the Cell's power is used to help offload some of the graphics processing from the RSX and whether this somewhat nullifies the supposed advantage the Cell has over the Xenon in the 360.
How much work must the SPU's do to compensate for the RSX's lack of power?
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Surely it depends greatly on the title?
Many people only "see" the CPU computational power. However, Cell's Local Store + DMA, the dedicated CPU and GPU bandwidth and split memory pools are also important. They reduce or sidestep slow memory access. The larger number of cores also help to provide a "burst" of power at any instance.
Although Uncharted 2 team claimed that they are utilizing 100% of PS3, it does not mean it has no more resources to run additional tasks. e.g., User can run PlayTV at the same time as Uncharted 2. No one has consistently peaked PS3 continuously.
It also doesn't mean that no more improvements can be made. Because the pipeline can be arranged differently on PS3 (e.g., rendering multiple frames at the same time vs only one), the developers can afford to spend more time on a frame. Smarter algorithms can also be used because the SPUs are more flexible. So developers have more leeway to find alternate (e.g., cheaper and smarter) approaches to implement the "same" thing, or better (see MLAA).
In a nutshell, the entire PS3 system works together to maximize the Cell advantage. The downside is it's difficult to program, and developers have to map their memory usage carefully.
As londonboy mentioned, it depends on the game. It also depends on the developers and problem on-hand because it's a question of software design (not just code execution). Raw computational power is only part of the Cell formula.
Although Uncharted 2 team claimed that they are utilizing 100% of PS3, it does not mean it has no more resources to run additional tasks. e.g., User can run PlayTV at the same time as Uncharted 2. No one has consistently peaked PS3 continuously.
It also doesn't mean that no more improvements can be made. Because the pipeline can be arranged differently on PS3 (e.g., rendering multiple frames at the same time vs only one), the developers can afford to spend more time on a frame. Smarter algorithms can also be used because the SPUs are more flexible. So developers have more leeway to find alternate (e.g., cheaper and smarter) approaches to implement the "same" thing, or better (see MLAA).
In a nutshell, the entire PS3 system works together to maximize the Cell advantage. The downside is it's difficult to program, and developers have to map their memory usage carefully.
As londonboy mentioned, it depends on the game. It also depends on the developers and problem on-hand because it's a question of software design (not just code execution). Raw computational power is only part of the Cell formula.
What makes you think it lacks power? If you use the Cell to cull and feed the RSX with the right data, perhaps it's more powerful? It has more raw FLOPS than Xenos after all.
The perceived advantage of the 360 perhaps has more to do with the familiarity of the API and the year head start of middleware.
More FLOPS but a lot less memory bandwidth than Xenos enjoys with the EDRAM.
It is rather telling to me that it seems Cell's SPU's isn't used so much for physics or AI or whatnot, or at least certainly that's not what gets the media's reporting attention, it's mostly used to help out the GPU. Not that I'm biased but my longstanding assertion is graphics drive the hardcore market and this certainly bears that out. Developers aren't saying "how can we use the SPU's to drive better AI" they're saying "how can we use the SPU's to help our renderer".
I think you can almost consider the PS3 a form of SLI, another tactic I've always thought would be interesting in a console (a dual GPU console).
That will change with natural interface gaming. Things like speech recognition, computer vision (motion and color tracking, object recognition using Kinect and PSEye cameras) are all AI problems.
They are getting a lot of media attention recently.
Some of the lag problems may be caused by the recognition subsystems.
The developers are getting into it as we speak.
is this still up for debate? I was under the assumption that pretty much everyone agreed that the xenos is better than the RSX. Almost every game, the xbox version is slightly better or about on par with the ps3. It's only when it's a sony developed game, where spu usage comes into play, that the ps3 games are graphically better than what's on the xbox. Sony should have at least added another 256 megs of graphics ram - then at least the textures could be better.
As a very rough estimate, I would say the rsx is about 90% the power of xenos.
scooby_dooby
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I could be wrong, but I don't think the bottleneck with AI has anything to do with CPU resources, and everything to do with programmer skill/knowledge.
After all, AI is essentially a giant next of "if" statements, nothing that would tax a CPU whatsoever. The hard part is actually writing "smart" code.
>_< (!)
You think Kinect (tracking and recognition) is a giant mix of "if" statements ?
scooby_dooby
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I'm referring to character AI, in a game. Not the actual console itself
But again, most of the processor intensive stuff there is going to be image/sound processing I would imagine. They would have a library responsible for processing images, and parsing data from those images, or parsing audio and distinguishing words.
I'm mainly referring to this idea that new console's, with more power, will give us "smarter" AI in our games. I don't buy it, and never have.
Although, when you get into the range of visual/audio recognition, then yes, that would totally apply.
I don't think that is necessarily the case. It's just that the majority of people are more interested in GFX and so that is what gets reported or queried in interviews.
I'm referring to character AI, in a game. Not the actual console itself
But again, most of the processor intensive stuff there is going to be image/sound processing I would imagine. They would have a library responsible for processing images, and parsing data from those images, or parsing audio and distinguishing words.
I'm mainly referring to this idea that new console's, with more power, will give us "smarter" AI in our games. I don't buy it, and never have.
That's only a subset of the problem space. e.g., I don't think there is any character AI in a Kinect or Move dancing game for example. It would be icing on the cake.
The basic body tracking and various recognition subsystems need sufficient CPU power to run (and may be custom chips to assist).
Phew !
If this * link and resource is right RSX ...
95 to 100% pixel shaders;
50/60% vertex shader;
110% MADD;
60/65% fill rate without MSAA;
30% Fill Rate with MSAAX2(w/alpha blend);
120% in texel rate(thanx to 24TMUs and flexio/XDRAM extra BW)
Overall -> RSX is 70 to 80% power of xenos gpu.
* Technologix blog -> Xenos/R500/C1 vs Geforce 7400/some ALUs G70 like...
http://forum.beyond3d.com/showpost.php?p=1150172&postcount=107
(Developers needs a good help to the SPUs for parity or exceed Xenos with well designed and built eDRAM)
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yikes! 70/80%? Where did all that silicon go? The RSX has like 300 million transistors. The xenos with mother and daughter die is like 310(?) million transistors. Seems that Nvidia just isn't good with their transistor budget.
Silent_Buddha
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I'm referring to character AI, in a game. Not the actual console itself
But again, most of the processor intensive stuff there is going to be image/sound processing I would imagine. They would have a library responsible for processing images, and parsing data from those images, or parsing audio and distinguishing words.
I'm mainly referring to this idea that new console's, with more power, will give us "smarter" AI in our games. I don't buy it, and never have.
Although, when you get into the range of visual/audio recognition, then yes, that would totally apply.
Majority of CPU time is generally spent on AI and Physics. Especially if you have AI with complex pathfinding routings and behavioral guidelines. And then multiply that by number of AIs and number of players (if co-op). Physics can use up all the processing in either of the consoles and still not be satisfied. Thus there's people dedicated to finding ways to approximate physics calculations such that while not entirely accurate look and perform well enough for X game.
Cell is a bit unique in that to extract good graphics performance you have to leverage CPU (well SPU) resources to assist RSX. Which is both a bane and a boon.
If you have the resources (time/money) you should be able to do some interesting things. If you don't then you end up with much worse graphics. Either way SPU along with additional resources (time/money) are required to achieve the same results as Xenos. On the flip side. It's certainly possible that if enough time and money were invested to leverage SPU that you might be able to do things impossible on Xenos.Does that mean with enough use of SPU's you can have equality with Xenos? No, not really. There are some fundamental hardware limitations that don't go away. But it does mean you should be able to do things that Xenos cannot.
Also remember Xenos is ahead of RSX with regards to rendering technology. RSX being fairly grounded in G7x/R5x technology while Xenos has some features of G8x/R6x generation in addition to the EDRAM and ability to access a larger memory pool if needed.
Regards,
SB
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Some of your figures are off because the blog (or were you the one doing the comparison calculations?) assumed a 550 mhz RSX speed when we know it's 500. So when he (you?) multiplies by 1.22 to compensate for his Geforce's 450 speed, he should actually multiply by 1.11.
Using this I get on his test, Xenos is 114% as fast at shaders, or RSX is 87% of Xenos. Whereas you list a shader figure of 95-100% (if you use the 1.22 multiplier it does come at 95-96%).
All of course on his one particular test.
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You right if RSX its only 500MHz but this blog talks about geforce 7400 in 450MHz and maybe this link *(and many dev talks..) explain the pixel shaders RSX have clock at 550MHz if not my mistake(you right 550MHz p.shaders is something like 95 to 96% or something between 90/100%).
* if this correct -> http://www.edepot.com/playstation3.html#PS3_RSX_GPU
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