RSX: Vertex input limited? *FKATCT

_phil_ said:
.

On the topic of plateform ,when we straight port our first Ps3 engine to X360 we had much better performances.Then ,becoming ps3 exclusive ,we did a lot of rethink and tuning (and up to date kits and libs) ,it 's now a lot much better than x360 's....
This Is normal ,when you have oportunity play with the strenghts.
Click to expand...

Of course it is. Following this logic tho, if you would have become x360 exclusive with up to date kits and libs directly from Microsoft and an engine tailored for 360, perfomances could have been very similar to ps3 ones.
Am I correct?
Someone asked the costs of each system OS.

According to this article http://dpad.gotfrag.com/portal/story/35372/?spage=6 , Everything comes at a cost and here are the costs for the 360. # 32MB of the 512mb of available GDDR3 RAM
# 3% CPU time on Core1 and Core2 (nothing is reserved on Core0)

Microsoft still has room left from what they’ve already reserved for future updates.

Transitioning to the PS3’s Operating system here is what the resource allocation looks like.

Sony of course has decided to match Microsoft by using a constantly running in the background Operating system and here is what it includes. Again I will not be going into what it offers as most already know by now.

The costs for the PS3’s operating system are as follows
# 32mb of the 256mb of available GDDR3 memory off the RSX chip
# 64mb of the 256mb of available XDR memory off the Cell CPU
# 1 SPE of 7 constantly reserved
# 1 SPE of 7 able to be "taken" by the OS at a moments notice (games have to give it up if requested).
 
X-AleX said:
...
Click to expand...

Any numbers on what memory resources the PS3 allocates is just rumors and speculation at this point. And there is no point discussing it because 1. It's already been discussed to death and it leads to fighting. 2. The information is under NDA so no one can back up their claims.
 
X-AleX said:
Of course it is. Following this logic tho, if you would have become x360 exclusive with up to date kits and libs directly from Microsoft and an engine tailored for 360, perfomances could have been very similar to ps3 ones.
Am I correct?
Someone asked the costs of each system OS.

According to this article http://dpad.gotfrag.com/portal/story/35372/?spage=6 , Everything comes at a cost and here are the costs for the 360. # 32MB of the 512mb of available GDDR3 RAM
# 3% CPU time on Core1 and Core2 (nothing is reserved on Core0)

Microsoft still has room left from what they’ve already reserved for future updates.

Transitioning to the PS3’s Operating system here is what the resource allocation looks like.

Sony of course has decided to match Microsoft by using a constantly running in the background Operating system and here is what it includes. Again I will not be going into what it offers as most already know by now.

The costs for the PS3’s operating system are as follows
# 32mb of the 256mb of available GDDR3 memory off the RSX chip
# 64mb of the 256mb of available XDR memory off the Cell CPU
# 1 SPE of 7 constantly reserved
# 1 SPE of 7 able to be "taken" by the OS at a moments notice (games have to give it up if requested).
Click to expand...

Don't know about how much memory the OS reserves ( heard it was 64 mb ) but 1 spe taking by OS at any moment is bullshit.

Edit

Dear lord the author of that article is clueless.
 
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X-AleX said:
Microsoft still has room left from what they’ve already reserved for future updates.
Click to expand...
And you think SCEI haven't got room for future updates..? That would be a bizarre thing to assume, especially when taking into account SCEI's fairly agressive firmware upgrades for PSP. I can see no reason why this would be different on PS3 - infact, Phil Harrison has (along with other SCE management) already said as much.

Anyway, this thread is getting way off topic... I'm surprised xbd hasn't popped up yet!

To kind of get back on track, my own view of it is that while it's unfortunate that the same systems & assets may not yield maximum performance on both platforms (for those doing multiplatform development), it's not exactly a surprise. And while some devs (DeanoC for one) may prefer using SPUs for game code rather than any GPU-related work, depending on what the goals of a specific project are, using SPUs to do trimming (and, at the same time, potentially doing progressive meshing, skinning, etc) doesn't seem unreasonable if you've got a *really* vertex-heavy application. A nice thing about the PS3 approach is that it's completely up to the developer as to what to use the SPUs for. Of course, the down-side of this is that multiplatform developers either need to accept that there are going to be differences in this area (code, assets, stripping algorithms, attribute packing, alpha fill-rate performance etc) and just deal with them, or develop their titles such that it's targetted at a base specification that's achievable on both machines with a minimum of platform-specific change.

The choice is theirs, based on their project timescales and resources. The top-tier of multiplatform developers will, I suspect, put the effort in. This is already evident by Joker's feedback to this thread .

Cheers,
Dean
 
I had originally heard that the OS reserved 96 total megabytes. However, the person who indicated that only had experience with an early devkit.

Then somewhere (I'm not sure where) I read that in the final commercial unit that the total memory reserved by the OS was 64 megabytes.

All I can say is that even though I believe that overall the PS3 has more potential to create better graphical effects (with a good bit of work programming the SPU's to help out the RSX) I think that Sony was a little greedy with the OS memory requirement.

If the 360 can make do with 32MB why could the PS3 not make due with it?

If the PS3 truly has either 32 or 64 fewer megabytes of free RAM for developers to work with that's a significant hint in my opinion.

I still think that the extra shading abilities of the RSX, the power of the SPU's, and the large storage space provided by Blu-ray will in the end make the PS3 the most powerful system and game developers will eventually admit it has the most absolute potential if you are willing to work for it.

But I can't help but think to myself that 64 or 96 megabytes is a LOT of RAM for the OS to reserve for it's own purposes.
 
We do not know what are the Sony's final plans as far as multimedia goes for the ps3, but from the beginning, Sony wants the ps3 to be a multimedia hub, whereas MS wants the xbox360 to be more like a Vista media center extender. That alone may means more processing and memory eaten on the ps3 side for the same task (the ps3 doing some task whereas the the same task could be done on the PC then streamed on the X360) ??
 
Would it be feasible, say, to sacrifice 1 frame latency to have the SPEs handle post processing (whilst RSX carries on it's merry way with the next frame?). I've wondered about that a bit.

I've also been thinking about things like cloth simulation. I'd expect very well suited to SPEs, yet at the same time xenos could probably do this very well, with a few textures representing the forces, etc.

Given an SPE culling geometry and streaming indices to RSX (thats how it happens?) - would there not be some fairly tricky sync issues? Might not the SPE have to sit idle waiting on RSX a fair bit?. Also I assume it's cache limited to how many triangles it can throw out before needing a refill? Would this hit the PPU (interrupt?) or is it capable enough on it's own?

I for one am curious to see what developers manage to crank out of the SPEs. (or is it SPU? I always thought it was sugargestic proclamation events.. ohh well)

Btw 2007 is awesome. Beware of the dragons though.
 
Last edited by a moderator:
DeanA said:
A nice thing about the PS3 approach is that it's completely up to the developer as to what to use the SPUs for.
Click to expand...

Indeed and the nice thing about having a bunch of SPU with a good task system, is its entirely possible to mix both types of programs (as a GPU enhancer and for gameplay system).

For example an area where SPU can benefit RSX a fair bit, is as Dean talks about as a geometry modifier (trimming small triangles, doing progressive meshing, HO tesselation, etc.). You can do this on either part of frame across all SPUs, or dedicate 1 or 2 SPU to the job and leave the others for general tasks.

I suspect you could do a similar thing on 360 CPU as well, to maximise the 2nd threads of each core. Put a cooperative job system on the 2nd hardware thread of each core, that picks up VMX128 jobs to assist R500... If your main threads weren't doing much VMX ops, that might actually be a good way to get both good performance...
 
Graham said:
Given an SPE culling geometry and streaming indices to RSX (thats how it happens?) - would there not be some fairly tricky sync issues? Might not the SPE have to sit idle waiting on RSX a fair bit?
Click to expand...
Depending on what scheduling system you use, idle time could be minimized. Similar to US versus fixed shaders, VS may be sitting idle, whereas in US, those units would switch to PS. When the SPE isn't needed for vertex work, shift it onto another job with the option to preempt out back to vertex work.

Nesh : I'm tempted to negative rep you for the above. You know screenshots of that size aren't allowed on this forum, and the GeOW vs. Resistence debate has already been removed from the thread. I'm sure the mods don't want to be cleaning up messes after they've already said what not to post about.
 
Shifty Geezer said:
Nesh : I'm tempted to negative rep you for the above. You know screenshots of that size aren't allowed on this forum, and the GeOW vs. Resistence debate has already been removed from the thread. I'm sure the mods don't want to be cleaning up messes after they've already said what not to post about.
Click to expand...

It wasnt intentional. Sorry about that. I didnt notice because I didnt follow the thread from the beginning.

Also I wasnt making a game VS discussion. Its a misunbderstanding if I gave that impression. I was only pointing out to the time frames and Unreal Engine 3's capabilities which should be the reason for the difference in visual results. And since this is a technical forum I wasnt refering to these as games either but mostly as developer's work exploiting hardware and features which differ due to more and other reasons than hardware limitations and similar development time.

With other words there was no point comparing Resistence with GoW to extract conclusions
 
X-AleX said:
The costs for the PS3’s operating system are as follows
...
# 1 SPE of 7 able to be "taken" by the OS at a moments notice (games have to give it up if requested)[/B].
Click to expand...

This isn't entirely correct. I'm going by what other devs have told me here, but of the 6 spu's nomally for dev use, Sony can use roughly 5% of one of them at a moments notice. As a fellow dev once told me, we effectively have 5.95 spu's. I haven't verified this though.
 
babcat said:
But I can't help but think to myself that 64 or 96 megabytes is a LOT of RAM for the OS to reserve for it's own purposes.
Click to expand...

Those numbers seem "more or less" in line with what we've seen. They don't include the edram that the 360 has though, on PS3 we have to use some of the precious vram for frame buffers, don't need to do that on 360. The 360's memory advantage is huge currently, although this could change if sony trims back their memory needs. I think this is a much bigger issue to multi platform devs like myself. If you just do PS3 then you may not be feeling the pain as much. Taking a 360 game that looks nice and suddenly realizing that you have to free up 60+ megabytes of memory sucks ;( Likewise, taking your PS3 game and porting it to 360 will leave you with gobs of memory free which you may as well use to improve visuals. This is one of the reasons why I've been thinking lately that our 360 version will always look better than our PS3 version. We try to be clever as to which textures we downsize of course, so it's entirely possible that the typical game player won't notice.
 
almighty said:
Unreal Engine 3 was first revealed in 2004, and even then it was looking extremely polished and complete. So Gears, if truth be known was in development for atleast 3+ years, how much better do you think Resistance would of looked if Insomniac spent 3 years on a game engine before they starting creating game assett's? ;)

Thats what annoys me when people compare PS3 game's to 360 one's that use UE3, UE3 is an extremely streamlined engine thats had years of work, 90% of PS3 launch game's use game engine's that id bet have'nt even had half of the time spent developing them as UE3.0 has.
Click to expand...

Oh, seems like I missed this one. Gears does leverage unreal, but Insomniac has also been leveraging an engine that Naughty Dog had written and tweaked for many many years as well. Seems like a fair comparison to me.
 
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