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Xbox 360 & PS3 feature poor processing power?

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A couple days ago, AnandTech did a very thorough investigation of the Xbox 360 and PS3. They followed up their report by talking anonymously to game developers and getting their opinions on the new consoles. The verdict? The processors are rather sub-par whereas the GPUs are quality stuff. The most damaging is that these consoles will not spur on a physics revolution, leaving it in and a stagnant state and allowing the PC market to pioneer this area of gaming.

This was the link to the article.

The article doesn't exist anymore. Here's what was written in Anand's forum: "PS3 article is pulled for now because Anand is worried about MS tracing his anonymous insider. "

Here's the article that is no more, I found this posted at xbox365.com forums

Microsoft's Xbox 360 & Sony's PlayStation 3 - Examples of Poor CPU Performance

In our last article we had a fairly open-ended discussion about many of the challenges facing both of the recently announced next-generation game consoles. We discussed misconceptions about the Cell processor and its ability to accelerate physics calculations, as well as touched on the GPUs of both platforms. In the end, both the Xbox 360 and the PlayStation 3 are much closer competitors than you would think based on first impressions.

The Xbox 360’s Xenon CPU features more general purpose cores than the PlayStation 3 (3 vs. 1), however game developers will most likely only be using one of those cores for the majority of their calculations, leveling the playing field considerably.

The Cell processor derives much of its power from its array of 7 SPEs (Synergistic Processing Elements), however as we discovered in our last article, their purpose is far more specialized than we had thought. Speaking with Epic Games’ head developer, Tim Sweeney, he provided a much more balanced view of what sorts of tasks could take advantage of the Cell’s SPE array.

The GPUs of the next-generation platforms also proved to be quite interesting. In Part I we speculated as to the true nature of NVIDIA’s RSX in the PS3, concluding that it’s quite likely little more than a higher clocked G70 GPU. We will expand on that discussion a bit more in this article. We also looked at Xenos, the Xbox 360’s GPU and characterized it as equivalent to a very flexible 24-pipe R420. Despite the inclusion of the 10MB of embedded DRAM, Xenos and RSX ended up being quite similar in our expectations for performance; and that pretty much summarized all of our findings - the two consoles, although implementing very different architectures, ended up being so very similar.

So we’ve concluded that the two platforms will probably end up performing very similarly, but there was one very important element excluded from the first article: a comparison to present-day PC architectures. The reason a comparison to PC architectures is important is because it provides an evaluation point to gauge the expected performance of these next-generation consoles. We’ve heard countless times that these new consoles would offer better gaming performance than anything we’ve had on the PC, or anything we would have for a matter of years. Now it’s time to actually put those claims to the test, and that’s exactly what we did.

Speaking under conditions of anonymity with real world game developers who have had first hand experience writing code for both the Xbox 360 and PlayStation 3 hardware (and dev kits where applicable), we asked them for nothing more than their brutal honesty. What did they think of these new consoles? Are they really outfitted with the PC-eclipsing performance we’ve been lead to believe they have? The answer is actually quite frequently found in history; as with anything, you get what you pay for.

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Haven't people been saying this since the specs first came out? I seem to recall something on Gamespot about how developers couldn't do complex AI on the new consoles because the processors weren't fast enough.

In any case, it just makes me look to Nintendo more.

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The reason that the Xbox 360 and PS3 are considered to have poor processing power for some tasks is that they don't do out-of-order execution.

Out of order execution means that a CPU keeps a pool of instructions to process, and it can reorder them to some extent to allow for better efficiency, provided that the commands don't depend on earlier results. So, for example you might have a piece of code like:

a = b * (c - d)

x = y + z

In an in-order CPU, like the new consoles have, then the instructions would be processed in order. i.e.:

c - d

b * result of (c - d)

y + z

An out of order CPU is capable of rescheduling instructions, so that it can use resources more efficiently. So if the CPU was waiting for the multiplication hardware to become free, the instructions would be reorganised to give:

y + z

c - d

b * result of (c - d)

Which would run faster than the code in its original order.

The big advantage of this is that you don't have to tune the program to the same extent to get it to run fast, and less deterministic, branching code will also be faster if branch prediction is employed. The comments made in the GDC "Burning Down the House" panel are an upshot of this. I haven't seen the Gamespot article, but I suspect that it says the same thing. Basically, it makes the CPU less good at being a general purpose unit.

So, why do it? The reason is that it takes up a lot of the chip's die space to implement an out-of-order design, and it looks like IBM, Microsoft and Sony have decided that more cores are more useful.

With regards to the Cell, it always looked as though the SPE were pretty limited purpose units anyway. (They always struck me as being big vector engines.) I heard a rumour that Apple didn't go with the Cell CPU for the Mac on the grounds that it didn't work as a general purpose CPU.

My guess would be that the Xbox 360 has a better general purpose CPU, whilst the PS3 will be better for doing large numbers of floating point calculations. Like Anandtech, I think that the consoles will be similar in terms of their overall performace, but will have quite different strengths and weaknesses.

There's been no official word about the Revolution as yet, but rumours suggest a dual core CPU at 2.8 GHz. It's possible that Nintendo have gone for an out-of-order execution part (fewer cores than the Xbox's, so possibly some free die space), but we'll have to wait and see.

The other thing to bear in mind is that previous consoles has offered graphical performance that's on a par with a contemporary top end gaming PC. I don't expect that latest consoles to be any different.

Graeme

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I should have said in the above that the Xbox 360 and PS3 processors won't be lacking in power, but rather it will be harder to utilise efficiently.

Graeme

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Nintendo really better step up to the plate here, for their own good. I don't know if physics and AI are ever the first things on their mind though. It always seems like it's practically effortless for them to improve upon existing types of gameplay and invent new ones that for some reason I get the impression that they (think they) don't "need" stuff like AI and physics. Who knows, though?

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I should have said in the above that the Xbox 360 and PS3 processors won't be lacking in power, but rather it will be harder to utilise efficiently.

Graeme

(hypothetical figures)

You may be using 40% more cycles or whatever, but you're getting 60% more cycles per second (particularly if you make use of the multiple threading options).

With regard to AI, I can't see the speed being a problem when you can run the intelligence routines in any one of 6 (or 8 or 10) threads.

There's also the fact that the consoles are pretty specialised for games or video; modern x86-style processors are very flexible and tend to be good at running numbers and heavy-client OS stuff as well as having to put up with the substantial overhead that this implies.

I don't think the gap between current PC hardware and the console hardware is very much different to that between the original XBox and the pentium 3's of the day.

On that note, Moore's law rears its head (not so much in CPU power, but currently one the graphics processors). We generally give consoles a life of 4-6 years (with some overlap between generations), while graphics cards are somewhere nearer 8-16 months. With each generation, the game between a 5 year old console and a current graphics card is going to be greater and greater. Are we likely to see shorter lifecycles as manufacturers launch their next-gens earlier and earlier to keep up with the cards or are we more likely to see a slowdown in graphics transistor density like we see with consumer CPUs today?

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The high end PC's of today are as powerful as the PS3. Granted they are waaay too expensive, but an SLI setup with 2 NVIDIA 7800's might even surpass the RSX chip of the PS3. Also the AMD Fx series now has dual core processors that will be common in a year or so. One major hardware advantage that the PC have is the PPU, something that is lacking from all consoles. If the next gen is all about the physics like they are claiming it to be, than the PC edges consoles by a big margin, seeing how it has a dedicated chip just for that, whereas the consoles have to delegate that job to the CPU.

At the end of the day it's like every new generation, the consoles rival PC technology at the beggining of their life cycles, but they fall behind within a few years.

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But with PC devs not even releasing games to take advantage of that new hardware, all of the platforms will be locked in software equality. Even in the last year we probably only had two games (Hl2 and Doom3) that weren't designed from the get go to be scaled onto the Xbox with ease.

So I bet PC gaming will never break away, the developers will hold it back almost as much as the huge costs.

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But with PC devs not even releasing games to take advantage of that new hardware, all of the platforms will be locked in software equality. Even in the last year we probably only had two games (Hl2 and Doom3) that weren't designed from the get go to be scaled onto the Xbox with ease.

So I bet PC gaming will never break away, the developers will hold it back almost as much as the huge costs.

Yeah I agree. The PC hardware last gen was underutilized and this gen will not be any better, because honestly PC games just don't sell as much. At least the consoles themselves are more powerful this time around, so we won't get a PS2 looking port on the PC.

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I suspect that the PS3's multiple threads won't be that useful for AI (though I'll probably be proved horribly wrong :) ), as I think that the SPEs are really big vector engines. That's one area where I think that the Xbox 360 could win in terms of processor design, though it's a case of wait and see.

The specs for the nVidia 7800 are pretty close to the RSX, albeit with a lower clock speed (450 to 480 MHz vs. 550 MHz). I'd guess that both chips will have a similar architecture, and I think that they have the same number of transistors, so a 7800 SLI rig should pwn the PS3.

I would expect to see a slow down in GPU performance increases - nVidia claimed to be way ahead of Moore's law at one point - simply because the current generation of chips have 300 million + transistors, making them hard to fab. One of the big limits on chip design in general is having the staff to actually lay out the gates, but I think that graphics hardware tends to use a lot of identical, repeated elements. (OK, the one I was briefly involved in did, but that was its USP.)

The PC gaming market seems to be less important than it was five years ago, and I don't think that it will drive a new generation much faster.

Graeme

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Yeah I agree. The PC hardware last gen was underutilized and this gen will not be any better, because honestly PC games just don't sell as much. At least the consoles themselves are more powerful this time around, so we won't get a PS2 looking port on the PC.

I don't even think it's just that PC games don't sell as well, although that's surely part of it. It's also that developers just don't bother being efficient. I've heard this from actual developers. Console developers learn to be incredibly clever when it comes to squeezing power out of the hardware they're working with, whereas it's not as much of a necessity for PC developers. I mean look at some of the stuff that's come out on PS2, which is clearly the least powerful current console. Can you ever imagine seeing stuff like that on a PC with comparable specs? Same goes for any of the consoles for that matter. There's also the problem of PCs being of such widely variable configurations. Since developers don't know exactly what they're working with, they are forced to take an approach that is at least somewhat compromised. I have no doubt that, as usual, PC games will start to edge out console games in terms of shininess, but I don't think it's going to be a particularly significant comparison.

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There's also the problem of PCs being of such widely variable configurations. Since developers don't know exactly what they're working with, they are forced to take an approach that is at least somewhat compromised.

That's a big factor ... and I've seen that from my personal experiences too.

I've been coding for the PC for quite a while (8 years), last year I decided to do some coding on the GBA. And what a great change that was! Being able to say, "okay, its running at 60fps on this GBA ... it'll do that on all GBAs" was actually unbelievable to me. I couldn't get over the fact that I could do any mad optimizations and know there wouldn't be any incompatibility problems.

The other thing is that hacks are possible on consoles, but not really on PCs. I've seen an incredible amount of "poke this value to this address and something-or-the-other will happen" for the GBA. Hardware-level stuff like that just isn't possible for the PC.

SiN

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