Is the PS3 Bandwidth enough?

[Garfunkel]

I have heard lots of people say that the ps3's bandwidth sux and that it is only 1/5 of the 360's What's the deal?

[xbdestroya]

I'm not going to answer the question of "is it enough" because I don't know, and certainly there are those that would also say "it's never enough."

But on the point of the 360 vs PS3 bandwidth, here's the deal.

PS3 has the greater bandwidth of the two consoles - not 1/5. Repeat, more bandwidth than 360.

BUT, the reason there is so much confusion on this is because of the eDRAM on the Xenos daughter-die. The bandwidth between the eDRAM and the R500 proper is incredible, and it carries the entire burden of the anti-aliasing, something that traditionally is a huge bandwidth hog. Some people try to calculate a way to include that daughter-die bandwidth into the main system bandwidth but you really can't do that - they're just too different.

So the best way to look at it is that the PS3 has more bandwidth - which is honestly the case - but the 360 is in a situation where it potentially requires much less bandwidth to perform it's graphics operations, because the internal bandwidth from the R500 to the daughter die relieves a huge portion of the load.

This might very well lead to the situation in which even though the PS3 has more bandwidth, it's still the RSX that is more frequently running up against a bandwidth-related bottleneck.

We need to wait for the RSX to be revealed before we can really make a solid judgement on that front though.

[rpgamer_2k5]

Yes_It's_Me: If that's the case then the PS2's bandwidth would have been several times greater than the Xbox since it also has eDRAM embedded on the GS. Even if you were to use such an incorrect comparison, the PS3 will still have a high bandwidth since the Cell's internal bandwidth is far greater than the eDRAM.

[saxdawg00]

Yes_It's_Me: If that's the case then the PS2's bandwidth would have been several times greater than the Xbox since it also has eDRAM embedded on the GS. Even if you were to use such an incorrect comparison, the PS3 will still have a high bandwidth since the Cell's internal bandwidth is far greater than the eDRAM.

Exactly. If they want to include the edram bandwidth, then they should also include the bandwidth between the Cell's PPE and SPE's (and the SPE's local storage too!) in the PS3.

[woundingchaney]

Exactly. If they want to include the edram bandwidth, then they should also include the bandwidth between the Cell's PPE and SPE's (and the SPE's local storage too!) in the PS3.


Quick question will the SPEs bandwith needs vary (drastically) concerning what application they are running???

Also with the architecture being so different is it safe to say you really cant compare one number to another (as far as architecture needs)??

[Viper]

I'd agree to that on many levels. Even with the current gen systems, comparing specs is an exercise in apple to orange to banana theory.

[xbdestroya]

Quick question will the SPEs bandwith needs vary (drastically) concerning what application they are running???

Also with the architecture being so different is it safe to say you really cant compare one number to another (as far as architecture needs)??

Your first question I can't speak to, but on the second question it's true a wholly apples to apples comparison can't be made. Still, there are some numbers that can be compared to one another, because they are equivelents to one another.

PS3 has more bandwidth, but 360 has a setup that greatly relieves bandwidth concerns.

If we're talking about graphics with 4x anti-aliasing turned on, 360 definitely is going to have more bandwidth left available to work with.

Really no other way to put it: PS3 has more, but 360 needs less.

This is kind of a repeat of my post earlier on, but I just want to drive home to some people that just because PS3 has greater bandwidth available to the GPU, it doesn't mean that the PS3 has the better bandwidth to the GPU.

Gotta give the 360 credit where credit is due! :rotate:

[woundingchaney]

Your first question I can't speak to, but on the second question it's true a wholly apples to apples comparison can't be made. Still, there are some numbers that can be compared to one another, because they are equivelents to one another.

PS3 has more bandwidth, but 360 has a setup that greatly relieves bandwidth concerns.

If we're talking about graphics with 4x anti-aliasing turned on, 360 definitely is going to have more bandwidth left available to work with.

Really no other way to put it: PS3 has more, but 360 needs less.

This is kind of a repeat of my post earlier on, but I just want to drive home to some people that just because PS3 has greater bandwidth available to the GPU, it doesn't mean that the PS3 has the better bandwidth to the GPU.

Gotta give the 360 credit where credit is due! :rotate:



With high def being a staple for next gen will every game incorporate high anti aliasing?

[xbdestroya]

With high def being a staple for next gen will every game incorporate high anti aliasing?

On the 360, yeah probably.

On the PS3, up to the developer if they want to use the bandwidth for anti-aliasing or something else (for better or for worse).

[rpgamer_2k5]

On the 360, yeah probably.

On the PS3, up to the developer if they want to use the bandwidth for anti-aliasing or something else (for better or for worse).

Xbs, lets keep in mind that Sony is the one that pioneered the eDRAM configuration found on the Xbox 360. Surely if Sony were to dump eDRAM they would definitely be implementing something that will be able to match it in terms of anti-aliasing. Since we no little to nothing about the RSX, it is so hard to even conclude anything.

[cpiasminc]

Really no other way to put it: PS3 has more, but 360 needs less.
That's true, but in addition, it's worth mentioning that neither of them has *enough* or anywhere near it in the specific parts where it would really count. 360 has loads of framebuffer bandwidth, but the main impact that has is that framebuffer bandwidth won't become a limiting factor. There's still plenty of other bandwidth limitations.

[makeitlookreal]

The XBOX 360's EDRAM is a great feature. I am very positive that Sony will have SOMETHING to counter that in the PS3's RSX.

[Grandia]

Hmm...now if I'm understanding this right, there was a reason that Sony didn't go with eDRAM. (I believe Kutaragi mentioned it in one of the interviews) Sony states constantly that the RSX is a joint development between the two. Now, like rpgamer said, Sony has to have known the benefits of having eDRAM, yet they still chose not to. So could it be that there might be something that they might help in the case of AA?

[xbdestroya]

Hmm...now if I'm understanding this right, there was a reason that Sony didn't go with eDRAM. (I believe Kutaragi mentioned it in one of the interviews) Sony states constantly that the RSX is a joint development between the two. Now, like rpgamer said, Sony has to have known the benefits of having eDRAM, yet they still chose not to. So could it be that there might be something that they might help in the case of AA?

Maybe there is - who knows? But as for the eDRAM, Sony's opting out this gen because without an exotic tiling technique as utilized by the Xenos, the size required for the eDRAM would be fairly large. If Sony wanted to implement it at 1080p, like they want to support, it would be enormous, and in and of itself become a key driver of cost for the entire console.

[Grandia]

Maybe there is - who knows? But as for the eDRAM, Sony's opting out this gen because without an exotic tiling technique as utilized by the Xenos, the size required for the eDRAM would be fairly large. If Sony wanted to implement it at 1080p, like they want to support, it would be enormous, and in and of itself become a key driver of cost for the entire console.
I hope so.
Ahh, that's it. I can see why Sony wouldn't want it then. The price for the PS3 as it is now must be quite a bundle.

[lip2lip]

Really no other way to put it: PS3 has more, but 360 needs less.

this may not be true. xbox360 uses unified memory that is only gddr, 22 gigs / sec. this is shared across the whole of the system, so 22 gigs is all you are going to get.

ps3 has 25 g/s main, 22g/s video, and 35g/s cpu to rsx, so you could say total bandwidth available for processing is 82gigabytes/sec.

the r500 to daughter die is 50 g/s but it is only used as a frame buffer (if you want 4x aa) so it is useless for programmable bandwidth concerns.

edit: the frame buffer in xbox360 is assume no more than four tiles, or 40 megs a screen, meaning frame buffer needs no more than a gig a second. implying buffer in latent no more than 20ms in x360, and 27ms in ps3. so the trade off is 60 gigs more bandwidth in ps3 at a trade off for 7 ms latency AND ONLY IF aax4 is used.