[Farid]

Originally Posted by PC-Engine

Neither CELL or Xenon are GP processors, but the PPE cores seems to be more GP than the SPEs. Xenon has 3 PPEs, CELL has 1 PPE and 7 SPEs.

All we have now is the peak ops/Flops performances for all the cores cited (PPCs/SPEs). And, therefore we can make projections and conjectures only based on these datas.

Now what we need is some insights from people who worked, a long time, with both architectures if what you want is to determine the real world integer/ floating point performances of thoses two CPU. But for that you'll have to wait a few years.

Originally Posted by PC-Engine

Stop making up BS man. Nobody here said SPEs cannot do GP work, heck even a GPU can do GP work. Do you even read what other people post?

Drop the attitude for a moment PC-E, it doesn't do you any good.

Originally Posted by PC-Engine

Well last time I check weren't you the one to demand proof while having ZERO proof of your own?

Better check yourself.

edited: No need to continue this discussion.

[ralexand]

Sounds like that 3x performance was bs when you take into consideration that general performance of the cpu dropped drastically. That's why I hate pr spin like that. In fairness though the games are looking better on beta than alpha, ie. pgr3 but who knows how the games are running.

[PC-Engine]

Originally Posted by ralexand

Sounds like that 3x performance was bs when you take into consideration that general performance of the cpu dropped drastically.

You know this for a fact? Unless you know the details of how GP dropped, stayed the same, or improved, you should stop perpetuating unsubstantiated assumptions and drivel.

[Tap In]

Originally Posted by ralexand

Sounds like that 3x performance was bs when you take into consideration that general performance of the cpu dropped drastically. That's why I hate pr spin like that. In fairness though the games are looking better on beta than alpha, ie. pgr3 but who knows how the games are running.

it's interesting that some of the posts in this thread are saying the SPEs will do great (read: better than the Xenon PPCs at GP code) AFTER devs have been given sufficient time to learn to optimize them.

With the next breath they say that Xenon has now been "proved" (based on this document) to be inferior and "uhh-ohhh big problems with the XCPU", without giving anyone enough time to figure out how to work with them.

[Titanio]

Originally Posted by Tap In

it's interesting that some of the posts in this thread are saying the SPEs will do great (read: better than the Xenon PPCs at GP code) AFTER devs have been given sufficient time to learn to optimize them

I'm not sure where you got that idea.

No one is saying that. A SPE won't be better than a PPE for "general purpose" processing.

My point, at least, is that they're not entirely dismissable when it comes to "general purpose" stuff either.

Originally Posted by Tap In

With the next breath they say that Xenon has now been "proved" (based on this document) to be inferior and "uhh-ohhh big problems with the XCPU", without giving anyone enough time to figure out how to work with them.

The contrast between MS's PR re. this and the apparent realities of development deserves highlighting. They were the one's putting the spotlight on "general purpose" performance and what they would deem to be ill-advised Sony design choices - yet their own would appear not to be a million miles apart. It's just funny that a key "strength" of Xenon as claimed by MS really isn't really a significant strength at all in absolute terms.

[PC-Engine]

Originally Posted by Tap In

it's interesting that some of the posts in this thread are saying the SPEs will do great (read: better than the Xenon PPCs at GP code) AFTER devs have been given sufficient time to learn to optimize them.

With the next breath they say that Xenon has now been "proved" (based on this document) to be inferior and "uhh-ohhh big problems with the XCPU", without giving anyone enough time to figure out how to work with them.

I agree it's pretty silly and hippocritical.

[ralexand]

Originally Posted by PC-Engine

You know this for a fact? Unless you know the details of how GP dropped, stayed the same, or improved, you should stop perpetuating unsubstantiated assumptions and drivel.

You're right, I don't know the facts and that's why I stated sounds like which is based on innuendo and rumors that have come out. I certainly hope the rumors are false for the games sake. I would hate to think that all that money and research was spent for something that's a step backwards.

[Tap In]

Originally Posted by Titanio

I'm not sure where you got that idea.

No one is saying that. A SPE won't be better than a PPE for "general purpose" processing.

My point, at least, is that they're not entirely dismissable when it comes to "general purpose" stuff either.

well maybe all were not saying better than a PPC core but my point was that they are wiling to give time to optimize SPEs but the Xcpu appeared to be "dead in the water". (my words )

What's being talked about here sounds pretty much just like what anand was saying in the pulled GP article of both Cell and Xenon. Given time I would imagine both CPUs will have solutions to these very early issues.

[Titanio]

Originally Posted by Tap In

well maybe all were not saying better than a PPC core but my point was that they are wiling to give time to optimize SPEs but the Xcpu appeared to be "dead in the water". (my words )

What's being talked about here sounds pretty much just like what anand was saying in the pulled GP article of both Cell and Xenon. Given time I would imagine both CPUs will have solutions to these very early issues.

Completely agree, but given the situation we find ourselves, some of MS's claims of advantage over Cell are looking even less convincing to me, and I'm wondering what else they've got. (See above also, I edited in a response to the latter part of your previous post).

[scooby_dooby]

How is it less convincing?

With the PS3 you only have a single PPE, in-order and not very strong.

The 360 has 3 of these cores, and has much more GP power up front.

In other words, dev's will be forced to rewrite code to run on the SPE's because the GP power of the PPE is insufficient.

Now, considering they already have to rewrite everything to be in-order, how much time do we expect them to have to rewrite AGAIN to optimize GP code to run using an SPE. My point is I don't think it will happen very often, and when it does it will be out of necessity because the PPE did not provide sufficient power.

So I don't think it's right to say they are roughly equal in GP power because the SPE's "could" be used, because the fact is the X360's GP power is much much easier to extract and will get utilized with less effort than extracting that power from the SPE's.

Without the SPE's the PS3 does not have very much processing power compared to the 360. The SPE's can't be discounted completely for GP code, but at the same time they dont make up for the fact the PS3 has much less GP power in it's main core.

btw - i've read the document in question. It was PM'ed to me a few weeks back. I don't see how you can come to the conclusion that the GP power advantage claimed by MS were false based on that. Whatever problems the XeCPU has, the PPE on the cell will have the same issues, but with 1/3 of the power.

And by and large according to that doc almost everything was faster on the Beta kits, with a few things marked as slower (don't have the doc on me, and the link is now dead)

[SanGreal]

So noone can reconcile these two comments for me?

Originally Posted by J Allard

we don't run general-purpose code

Originally Posted by J Allard

But what you forget is, in today's game programs FP operations are 20% and the rest 80% are general integer operations or operations such as branching. They ignore that part. Integer operations are the most computation-cycle demanding part in game programs. Now, XBOX 360 has 3 times the integer processing performance of Cell.

Taken from the same interview

What is the difference between the two? Is he just talking about crap like excel in the first comment?

[Titanio]

Originally Posted by scooby_dooby

With the PS3 you only have a single PPE, in-order and not very strong.

The 360 has 3 of these cores, and has much more GP power up front.

In absolute terms, though, it's weaker than desktop chips. If general purpose performance was so important, why not stick a dual core desktop derivative in there? They obviously see things more like Sony do than they're willing to admit.

Originally Posted by scooby_dooby

In other words, dev's will be forced to rewrite code to run on the SPE's because the GP power of the PPE is insufficient.

Is it? Tim Sweeney doesn't think so. Also, what proportion of execution time is taken up by code that would be REQUIRED to run on the PPE? Tim Sweeney says: small. Let's not forget that we've got a core here running 10x faster than PS2's CPU.

(I'm sorry to harp on with Tim Sweeney this and Tim Sweeney that, and while "your mileage will vary" from game to game, he's been about the only dev to comment on this explicitly).

And again, if GP was as important as MS claims, why did they go with the setup they did?

Originally Posted by scooby_dooby

Now, considering they already have to rewrite everything to be in-order, how much time do we expect them to have to rewrite AGAIN to optimize GP code to run using an SPE.

I'm not saying it'll be either easy or happen immediately. But if discussing technical potential..

Xenon is a little easier to work with, I've no doubt. But Cell will gain more and more as devs work harder. I think we should judge how useful those SPEs by what the best devs do with them - this is about what they can do. It's very much an open question, but it will require talent. Putting a bad driver in a ferrari and then berating its performance seems illogical - the car isn't technically any less capable than it was before.

I should also note that the PPE ISA and the SPE ISA is supposedly identical, IIRC, which should make life a little easier if trying to shift code from the PPE.

Originally Posted by scooby_dooby

btw - i've read the document in question. It was PM'ed to me a few weeks back. I don't see how you can come to the conclusion that the GP power advantage claimed by MS were false based on that. Whatever problems the XeCPU has, the PPE on the cell will have the same issues, but with 1/3 of the power.

I'm not claiming there's no advantage, necessarily. Just that it rings a little hollow when you consider it in the bigger picture. To pull up the same analogy I used earlier, it's like an average student berating a less than average student for his academic performance - all the while completely ignoring his much greater talent elsewhere (talent which can be adapted to some unknown degree to help with his academic performance to boot).

[ralexand]

Originally Posted by Titanio

In absolute terms, though, it's weaker than desktop chips. If general purpose performance was so important, why not stick a dual core desktop derivative in there? They obviously see things more like Sony do than they're willing to admit.

I kind of wish that one of the console developers would have went to someone besides IBM for their cpu that way we could really see the performance difference in the in order and out of order processors.

Originally Posted by Titanio

Xenon is a little easier to work with, I've no doubt. But Cell will gain more and more as devs work harder. I think we should judge how useful those SPEs by what the best devs do with them - this is about what they can do. It's very much an open question, but it will require talent. Putting a bad driver in a ferrari and then berating its performance seems illogical - the car isn't technically any less capable than it was before.

I should also note that the PPE ISA and the SPE ISA is supposedly identical, IIRC, which should make life a little easier if trying to shift code from the PPE.

Sounds alot like what people were saying about tapping into the power of the ps2's vus vs. the celeron in the xbox.

[PC-Engine]

And again, if GP was as important as MS claims, why did they go with the setup they did?

What do you mean the setup they went with???

The setup as AFAICS looks like a nice balance between GP and FP.

[blakjedi]

How did this thread become a XeCPU vs Cell thread? I thought it was supposed to be about what was left out of the Xenos and RSX that should have been in there...

Is it because people feel that it is unfair to compare the Xenos and RSX directly (which still isnt what this thread is about mind you) because the RSX needs the Cell to operate at full capability?

Leave a thread unmonitored for a second and looks what happens. Please leave the XeCPU vs CELL argument to the billion other threads that have talked about that before.

[Titanio]

Originally Posted by ralexand

Sounds alot like what people were saying about tapping into the power of the ps2's vus vs. the celeron in the xbox.

There are many differences here. The VUs and the SPEs are quite different. Capability aside, many more devs will be using the SPEs more fully than those who used the VUs. PS2's main core was weak compared to the Xbox CPU also (and arguably the weak link in the whole chip). Here there is no clockspeed advantage, and the PPE and Xenon cores are reportedly pretty much the same. If you look at a pure plurality of resources - although this is somewhat simplistic admittedly - if you were to match SPEs off against cores as one might match VUs off against the Xbox CPU, that's 2 VUs (one less capable than the other) and a mips core against one celeron CPU vs one PPE against one Xenon core - pretty much the same - and 7 SPEs against the two remaining Xenon cores.

A very different kettle of fish, IMO.

Originally Posted by PC-Engine

What do you mean the setup they went with???

The setup as AFAICS looks like a nice balance between GP and FP.

The setup they've gone with sacrifices "general purpose" performance to try and bring them within a more respectable range of Cell-like floating point/streaming performance. If games are so heavily biased toward general performance as they suggest (80/20), why did they do this?

[PC-Engine]

The setup they've gone with sacrifices "general purpose" performance to try and bring them within a more respectable range of Cell-like floating point/streaming performance. If games are so heavily biased toward general performance as they suggest (80/20), why did they do this?

Maybe because they couldn't put 3 G5 cores with 3 VMX units on a single die?

[scooby_dooby]

I don't know, I think if you judge by the "best" possible, the CELL wins everytime. I think that's a ratehr convenient way of looking at it if you are a CELL fan.

What about a more realistic outlook? Like, what really will the SPE's be able to do, how un-efficient will they be USUALLY, what's the likelihood of extracting all this power?

As for the PR comments, hey sony plays up FLOPS, so MS plays up GP, does it really matter? Anything both camps say is pretty much tongue-in-cheek, like does anyone actually believe that they believe what they're saying?

I don't see the relevance of comparing to a desktop CPU, there's many other reasons not to choose a desktop CPU, mainly costs. In comparison to the PS3, which is the only comparison that matters, it does have very strong GP performance.

As for their claims ringning hollow I guess it depends how you look at it. You might argue MS considered the lack of GP power in the PS3 a large design flaw, and that MS was simply pointing out a flawed design, and although their CPU is no GP moster, it certainly has much more power than the PS3 does, so what';s wrong with them pointing out this rather glaring weakness?

At the same time I don't know if Sony can make the same claim in regards to X360 and it's FLOP power, as it is quite strong and definately couldn't be described as weak.

i think MS believes they have a better balanced system, and the comments referring to GP power were to try and illustrate that point. Take the focus off FLOPS for a little, and put the spotlight on the PS3's big weakspot, GP performance.

[Titanio]

Originally Posted by PC-Engine

Maybe because they couldn't put 3 G5 cores with 3 VMX units on a single die?

But even just 2 would apparently be better for GP? And that's your focus in a game...

...right?

And they wouldn't have to be G5s to be more GP.

[pegisys]

The setup they've gone with sacrifices "general purpose" performance to try and bring them within a more respectable range of Cell-like floating point/streaming performance. If games are so heavily biased toward general performance as they suggest (80/20), why did they do this?

because they wanted games to be easy to port, they know sony is still going to have more support, even if it doesn't stay that way, and if games are made with high floating point performance in mind they don't want to be waiting long periods of time for a port, I think that may have been the reason they went with ppc in the first place instead of a multicore x86 cpu, well that and maybe price

[PC-Engine]

Originally Posted by Titanio

But even just 2 would apparently be better for GP? And that's your focus in a game...

...right?

And they wouldn't have to be G5s to be more GP.

Maybe FP wasn't high enough with only 2 G5s? Why not just use one core with a 80/20 split. See what I'm getting at? If their minimum was 60 for FP then they would need 240 for GP which wouldn't fit into a single die so instead of cutting the 60 which is the bare minimum, they went and cut the 240 down to 180 to fit on a single die.

[version]

G5 isnt SMT, x360's large memory latency kill the g5's performance

[overclocked]

Dont know how the Xcpu differences from the PPE but i think that many here forget bacause they are so biased that $ony have had quite some more time with its partners to deliver Cell vs MS and even that is an understatement. Although all the cash and time spended on Cell wont "guarantee" a sucess i find it likely that Cell is indeed going to deliver much in terms of performance. Compared to PS2 that was a pain to code for and compare to Cell witch already have tools and software this long before launch.
So i think the ones here that dont belive in Cell as a good Cpu will change your mind when your in the local compstore next year.

Btw all this bias and fanboyism is really hurting the Forums and although Sonic as a mod keeps up a good spirit most of the times i really think that you Jvd should hold your negatives against $ony because you are a mod and its not really serving this commuity with an attitude like that. Keep it for yourself or quit as a mod and let someone else less biased take your role.

[Titanio]

Originally Posted by scooby_dooby

As for the PR comments, hey sony plays up FLOPS, so MS plays up GP, does it really matter?

Yes, it does. People often say this - Sony played the flops game, so why should we complain about MS? Well, it IS different! As already mentioned earlier, Sony used a well understood and verifiable metric (on paper), and credited Xenon fully. MS's "metric" is completely non-transparent and completely arbitrary. As long as the SPE's potential contribution to "general purpose" performance is non-zero, that comparison is flawed. Furthermore, it's very annoying, because while it's "case closed" on Cell's biggest strength (fp), we remain in this quagmire of conclusion-less debate about an area of supposed lesser performance for Cell, that may or may not even be that big an issue (see: Sweeney). Pretty clever on MS's part - because we can't come to any conclusion, this debate about a Cell "weakness" will continue - and that's just how MS likes it.

Originally Posted by pegisys

because they wanted games to be easy to port, they know sony is still going to have more support, even if it doesn't stay that way, and if games are made with high floating point performance in mind they don't want to be waiting long periods of time for a port, I think that may have been the reason they went with ppc in the first place instead of a multicore x86 cpu, well that and maybe price

Well, porting from PC isn't going to be very easy - some devs are crying for their intels and athlons, it seems. And if they want to be closer to Sony, why not go the whole hog? I'm not so sure that they didn't because they didn't want to.

Maybe FP wasn't high enough with only 2 G5s? Why not just use one core with a 80/20 split. See what I'm getting at? If their minimum was 60 for FP then they would need 240 for GP which wouldn't fit into a single die so instead of cutting the 60 which is the bare minimum, they went and cut the 240 down to 180 to fit on a single die.

60 for FP? What?

If things were as biased toward GP as they claim, why didn't they bias their chip toward GP instead of this "balance"..?

[scooby_dooby]

It seems like you think MS invented the idea that SPE's are horrible for GP code.

Has this not always been pretty much accepted? They are floating point monsters that's their strength, and from what I can gather not only are they weak at integer operations they are qctually quite terrible.

Now I understand your point, that the comparison is flawed. However, what do you propse MS should have done?

Do you think they should simply have not made the comparison at all? Despite that being their MAIN CPU advatange of the CELL? let Sony win the day with their FLOP count and stay completely silent about their GP advantage?

Or should they have come up with some arbitrary, unproven, value for each SPE's GP performance?

I mean I don't see really how they could make a comparison and accurately include the GP performance of teh SPE's.

But honestly, they are supposed to be pretty terrible, so what's the likelihood of them being used for anything signifigantr in real world scenarios?? Given that, I think the comparison is more or less valid even if it isn't the magnitude they suggest.