How important is system bandwidth - Page 2

pApA SmerF01 · 22-08-2005, 04:30 PM

Quote:

Originally Posted by shaun

i think you might be missing something there. the massive amount of bandwidht you speak of comes largely from the video chipset. in saying it's only a card in the deck, i mean the video is only one part... when you compare the actual speed and power of both cpu's, the memory, and the i/o subsystem, the only strong point in bandwidth is the xbox360's embedded dram->vpu speed...

and being microsoft, they overquote everything (Windows XP is the most secure version of Windows EVARRRR)

Also - Efficiency? There's no "Efficiency" factor. You've got to take into account, yes they disabled one of the SPE's for redundancy (and to cut down production costs), but you can't simply say that a processor is going to be running at 50-80% of its total power due to "Efficiency" That's a gross overstatement, and in that statemnt lies an inherent turnaround -- The XBox360's CPU is also a custom chip, with three cores, which if you think about it, if there are ANY flaws in the die of a three core chip vs an 8 core chip, which is going to suffer more?

Once again, not to sound like a fanboy, but really those numbers are quite inflated. I'll stretch to say the XBox360 has a monstrously better graphics subsystem, but cell was designed to work in many ways...

Do you know that IBM states that Cell is capable of running two operating systems at once with no degrade in performance? And once again, I'll state that at E3 when people were blown away by the PS3's graphics performance, the graphics shown were being rendered by Cell, not by RSX.

I swear I'll stop spamming you foruums with BS, but i like talking to this guy

okay, here we go....

look, when i say efficiency, i mean the total input/output performance of the hardware compared to what it feasibly can achieve running at MAX power. you know, the number it'll never reach, but the creators like to brag about it anyways?

i say 50-70% efficiency because not only will one spe be latent, but the spe's can only handle certain, low-grade tasks.

with no branch prediction, it comes down to real-time thinking within milliseconds and if it doesn't meet the per-cycle clock ratio, you'll get backed up and the information has to be transferred to different sectors.

the ppe is the ONLY general processor in the package, and since it has to run most intricate AI, code/breakdown scenarios, data decompression, and multiple other tasks per cycle, it'll be overworked and there will be backload. since it doesn't get any real help and the spe's are filtered through it, it needs more bandwidth to actually be able to transfer needed data in real time to where it needs to be. but since it doesn't have the cushion of bandwidth, each clock cycle you get a backup.

for the 360, they designed the xenos almost perfectly. the only flaw is less cache memory bank for storing running code and such. it's way more efficient in many different ways thanks to the generality of the cores. they each help eachother, and since they are running out-of-order, you get more data flowing so no backup. they all have branch prediction and feed off of a big enough main memory bank.

you're intelligent enough to hold a very decent tech debate, which i had been waiting for, but trust me. i do this part-time, i help my buddy develop. i've seen the xbox360 hardware up close, i've touched it, dinked around with it, ran code through it, created code for architecture....i know what i'm talking about.

if you want to know the one thing i look forward to that will sway graphical and create real-time photo-realistic worlds with total independent moving ai and objects (you know, a gamers dream), look at the xbox360's ability to perform procedural synthesis.

pApA SmerF01 · 22-08-2005, 04:34 PM

and one more thing, if you want to talk about overstatements, what about sony?

remember the emotion engine? toy story-like graphics on the ps2?

need i say more? sony lies through their teeth about a lot of stuff, but xbox has delivered on almost everything promised. that's another reason i'm choosing the 360 over sony's console.

citizen X · 22-08-2005, 06:49 PM

Quote:

Originally Posted by shaun

I'm not trying to be flamebait here, but I saw a couple of mistakes in your original post --

One: 7SPE's . SPE stands for 'Synergystic Processing Element' The PS3 processor has 7 of these. Each SPE has an SPU, and each SPU is capable of eight floating point instructions per clock cycle. Source, also the Cell processor is capable of SMT, such as the Pentium 4 or IBM POWER5.

The core design of the cell allows for multiple SPE's to process at once.

2. Total system processing power. Great, the xbox has more system bandwidth, probably due largely to the integrated on die memory for the video chipset. While this is a welcome performance gain, the CELL processor is capable of assisting the RSX with graphics (Note that all PS3 rendered images at E3 were running off another cell processor, not RSX)

And having said that, we've all seen taht the totall system processing power (including GPU)

Microsoft XBox360 - 1 Teraflop
Sony PS3 - 2 Teraflops

That can account for a prettty hefty chunk of graphics processing.

However, the XBox360's GPU is unique, and I do believe that the 256gb/sec bandwidth will be a welcome increase, and largely due to the on die memory. With this setup 16 or 32 megabytes would be equivalent to a 256 or 512mb card nowadays.

I realize this is an Xbox forum, but if you're going to educate people, at least do it correctly. The xbox definately has its strengths, but know your enemy before yuo bash it.

I'm not going to sit here and argue aimlessly with xbox fanboys or ps3 fanboys, i just found it necessary to add my two cents.

Yeah I am a little one sited; u can’t expect me to trust Sony when the first thing they showed was Kill zone 2, CG MOVE? Only Sony has the nerve to show a cg movie in a game convention and call it real time and then make a excuse and then say its what we expect the console can do, why the hell would u need to pretend to play a CG move with that PS2 controller, just so u can lie about later, and yet some people bit the bait, and now we get those fan boys who are saying that “no it was real time they said it was, its going to be 3 times more powerful then the x360 bla bla bal” !!!BS!!!

And about the bandwidth, not being the most important, so called “card in the deck” it’s the nerves system of the console that connects every part together, u know that. If u think of it, every console Sony has made, always had insufficient bandwidth.

About that cell rendering on its own, there is a reason why they still need a GPU. The graphics weren’t that impressive, it was beneath next gen. standard, it dint even have textures. And not even the physics were that impressive, but making a CPU do graphic is pointless, it’s a good thing there still using GPU

You can say what ever u won’t, I may be one sided, but I’m still right, a console may have the most powerful CPU in the world, but with sh*** bandwidth it mite as well be a G5 MAC

shaun · 23-08-2005, 08:20 AM

careful, you'll rile up the apple fanboys. and i assure you the apple fanboys are much worse then sony or microsoft fanboys.

on a side note, i'm writing a comparative article for my website, should be up within the next week or so, i'm citing both of you, and also doing a deeper comparison based on release specs.

once again, thanks for non flaming responses

pApA SmerF01 · 23-08-2005, 03:35 PM

Quote:

Originally Posted by shaun

careful, you'll rile up the apple fanboys. and i assure you the apple fanboys are much worse then sony or microsoft fanboys.

on a side note, i'm writing a comparative article for my website, should be up within the next week or so, i'm citing both of you, and also doing a deeper comparison based on release specs.

once again, thanks for non flaming responses

ick....i know apple fanboys. they're worse than nintendo fanboys. i've gotten into it with them when i said that 2 apple G5's were insufficient to run alpha kit hardware in the next gen. they nearly had a stroke!

if you would, please put the article up here as well, it should be an interesting read.

shaun · 23-08-2005, 10:59 PM

hit me up with an email

shaun [at] pixelefx [dot] com

i'll let you see it, it's being proofread right now, i'll be posting it soon

RSFlux · 24-08-2005, 01:50 AM

I may as well throw my two cents into the mix

I feel you are making a lot of good points, Citizen, but I feel that you're touting some features of the 360 that aren't as strong as you make them out to be. The total bandwidth for the 360 is indeed an impressive number, but that number is made up primarily of the size of the pipe between the GPU and it's eDRAM. While this speed will allow for some awesome advances in certain rendering techniques (such as FSAA, motion blur [see Project Offset] and oher post effects), the bandwidth left to the rest of the system is not severely different than the PS3's. It is larger, but not to the extent that you made it out to be in your first post.

Simply, my point is a reiteration of your first point: That the system can only be as strong as it's weakest link. I know the chain analogy is overused, but it's very true in game programming. With many processes running in lockstep, if ANY one part of the system slows down, EVERY part of the system slows down. This not only means that a low total bandwidth will slow performance, it also means that if a specific segment is slow performance will suffer.

Now, how much will this effect the games that run on these systems? It really comes down to the programmers. The biggest problem I see with the PS3 is not specifically that it is lacking bandwidth, but that it requires so much finesse from the programmer that it would be all-but-impossible to use the system to it's potential. The PPE needs to have an even distribution of branching and data crunching instructions (that it can hand to SPEs), otherwise it will bottleneck. No code I have ever written, let alone multi-threaded, has an even distribution of this. The SPEs don't have branch prediction, so need to have their cache manually set for good performance. All 7 of them. This seems to me like it would be back to programming in assembly. If you're going to use the SPEs for procedural generation, you need to time it so the massive flow of geometry will not block the pipes to the GPU while trying to load, say, textures, even while multithreading.

With the XBox 360, these problems do not seem to exist. So while it is possible that (assuming the PS3 is indeed as powerful as they claim) the PS3 could create better games, the programming to do it would make development a living hell. With the increased needs (and costs) of moving to a next gen system, I don't see that ever happening. Add in XNA, the Live service and at least an extra 6 months on the system, I think developers are going to be much happier on the XBox.

~Flux

pApA SmerF01 · 24-08-2005, 12:57 PM

beautiful post, flux.

you certainly hold enough knowledge about these systems as to keep this forum happy. finally some more technologically-sound members.

i have to agree with your analogy, and yes it's true that most of the number does come from the interconnectivity of the gpu and the dram, but taking that number out, and considering it's "system-share" bandwidth, it's still more than 2x the amount of the ps3 bandwidth.

oh, and my email is korneater_980@hotmail.com

citizen X · 28-08-2005, 10:31 PM

Quote:

Originally Posted by RSFlux

I may as well throw my two cents into the mix

I feel you are making a lot of good points, Citizen, but I feel that you're touting some features of the 360 that aren't as strong as you make them out to be. The total bandwidth for the 360 is indeed an impressive number, but that number is made up primarily of the size of the pipe between the GPU and it's eDRAM. While this speed will allow for some awesome advances in certain rendering techniques (such as FSAA, motion blur [see Project Offset] and oher post effects), the bandwidth left to the rest of the system is not severely different than the PS3's. It is larger, but not to the extent that you made it out to be in your first post.

Simply, my point is a reiteration of your first point: That the system can only be as strong as it's weakest link. I know the chain analogy is overused, but it's very true in game programming. With many processes running in lockstep, if ANY one part of the system slows down, EVERY part of the system slows down. This not only means that a low total bandwidth will slow performance, it also means that if a specific segment is slow performance will suffer.

Now, how much will this effect the games that run on these systems? It really comes down to the programmers. The biggest problem I see with the PS3 is not specifically that it is lacking bandwidth, but that it requires so much finesse from the programmer that it would be all-but-impossible to use the system to it's potential. The PPE needs to have an even distribution of branching and data crunching instructions (that it can hand to SPEs), otherwise it will bottleneck. No code I have ever written, let alone multi-threaded, has an even distribution of this. The SPEs don't have branch prediction, so need to have their cache manually set for good performance. All 7 of them. This seems to me like it would be back to programming in assembly. If you're going to use the SPEs for procedural generation, you need to time it so the massive flow of geometry will not block the pipes to the GPU while trying to load, say, textures, even while multithreading.

With the XBox 360, these problems do not seem to exist. So while it is possible that (assuming the PS3 is indeed as powerful as they claim) the PS3 could create better games, the programming to do it would make development a living hell. With the increased needs (and costs) of moving to a next gen system, I don't see that ever happening. Add in XNA, the Live service and at least an extra 6 months on the system, I think developers are going to be much happier on the XBox.

~Flux

I agree. The Xbox 360 was design with the developers in mind, that’s one of the reasons why the 360 has a unified pipeline. It gives the developers a chose of how to program the game, with out so many restrictions. Shore the PS3 has the potential to make better game but at what cost, thousands of more man hours, more ours means more cost. Why would developers wont to make games on console that is a b**** to develop for, and when in the time it takes to make one game they could have bin half way finished with their second. The programming code for the PS3 needs to be very clean and specific, do to the fact that a small bottleneck in a very limited amount of bandwidth is very dangerous to the system as a whole,

The x360 has much more bandwidth, so the developers, manly the programmers don’t need to worry so much about keeping the code clean, but sins the 360 is a multi core design like the PS3, it still needs to have cleaner code then the current generation.

About my article it was really meant to explain what system bandwidth is, because some people really didn’t know any thing about the bandwidth. So I tried to keep it simple.

I agree. The Xbox 360 was design with the developers in mind, that’s one of the reasons why the 360 has a unified pipeline. It gives the developers a chose of how to program the game, with out so many restrictions. Shore the PS3 has the potential to make better game but at what cost, thousands of more man hours, more ours means more cost. Why would developers wont to make games on console that is a b**** to develop for, and when in the time it takes to make one game they could have bin half way finished with their second. The programming code for the PS3 needs to be very clean and specific, do to the fact that a small bottleneck in a very limited amount of bandwidth is very dangerous to the system as a whole,

The x360 has much more bandwidth, so the developers, manly the programmers don’t need to worry so much about keeping the code clean, but sins the 360 is a multi core design like the PS3, it still needs to have cleaner code then the current generation.

About my article it was really meant to explain what system bandwidth is, because some people really didn’t know any thing about the bandwidth. So I tried to keep it simple.

And like papa said, “finally some more technologically-sound members.” Good to have u on the forums.

shaun · 30-08-2005, 11:34 AM

I'm posting the article tomorrow. (Wed)

Also, if any of you are interested, we're interviewing Pete Hines about oblivion at the middle of next week, so if any of you want to drop by our forums and post some questions you want to see asked, you're welcome to.

Thanks

VictoryOverWar · 30-08-2005, 12:52 PM

i know how to turn on my xbox...can i talk about specs too =).....most this stuff is over my head but i love to read about it. Keep the knowledge coming

daniel.isaac.h · 31-08-2005, 04:58 PM

I totally agree with Flux... In the end it will be the programmers that hand a victory to either Microsoft or Sony... Remember what the Xbox is capable of doing at 733 Mhz... Really, the programmers have the last say... Microsoft has already allocated quite a bit of funds and staff to developers to best utilize the 360... Truly we don't know what the PS3 is capable of yet... When I look at Killzone (2)'s graphics and compare them to other PS3 titles they look a lot better on Killzone hmmmm... Has me suspicious too.

shaun · 02-09-2005, 11:13 PM

okay here it is

http://www.pixelefx.com/index.php?pa...me=consolewars

be gentle, it's one of my first tech-minded articles

daniel.isaac.h · 03-09-2005, 12:26 AM

Good read shaun... But the 360 is slated for November, and the PS3 could be pushed back to 2007... Sony plans on keeping the PS3 in the market for 10 years too... Not sure where Microsoft stands on their market strategy length but I've heard only 4-5 years, that would make an interesting add to your editorial. Irregardless, good read!

G4everX · 03-09-2005, 12:56 AM

Quote:

Originally Posted by daniel.isaac.h

Good read shaun... But the 360 is slated for November, and the PS3 could be pushed back to 2007... Sony plans on keeping the PS3 in the market for 10 years too... Not sure where Microsoft stands on their market strategy length but I've heard only 4-5 years, that would make an interesting add to your editorial. Irregardless, good read!

There is a VERY slim chance that the PS3 will be pushed back tell 2007. They would drop a larger chunk of their market share, and Sony NEEDS ALL they can get right now.

Yes, the PS3 will have a 10 year life span, but that means it will be sold for 10 years. It will be replaced in about 5-6 years, but still be on the market for the next 4-5 years, just like the PS1 is now and the PS2 will be.

shaun · 03-09-2005, 10:42 AM

.. my bad on december, i meant november, thanks for the catch ..

I wouldn't say that sony NEEDS anything right now, look at the current market share.

Sony dwarfs microsoft when it comes to consoles.
6 months is nothing.

Sony had considered originally pushing the PS3 back, but the only reason I could see them doing that is to bring the console's price down, which I don't see as being that serious. Microsoft releasing a 399 console was a definate plus for Sony, that means that instead of selling at 299, they can do 399 and not lose near as much money.

I'm banking on a $300 PS3 though, I think Sony has enough money to sell at that, and if they release at $300, they'll murder XBox360's sales, even with a 6 month lead. You all know this.