forums.ps2dev.org

[jean]

My first thesis was on GPGPU - "General Purpose computation on Graphical Processing Units" - i.e. the answer to the question:

<< How could I trick a Graphical Processor and make it think it is computing Doom 3's reflection while actually it is accelerating serious computations (not necessarly related to graphics...) ????>>

Three years ago using GPU to speed up arbitrary (parallelizable) computations in SIMD fashion was little more than a nerd's game...today it is lagely used (and is leading to the use physical processors). I tryed to search for "gpgpu psp" and found nothing. So my question is "Is PSP's GPU suitable for GPGPU??" This translates into:

1) Does PSP's GPU own something like a _programmable_ pixel/vertex shader?

2) Can we instruct PSP's GPU to render into an hidden buffer?

Luckyly, the second question is quickly answered by the pspsdk itself 'cause renderTarget demo is doing exactly this.

Ideas for the first question??

jean

[noxa]

The GE is a fixed-function pipeline - no real programmability. About all the GE can do is jump/call other display lists based on bounding box tests, and I'm not even sure that's fast enough to justify doing it there (I haven't seen it used).

[Be3f]

http://forums.ps2dev.org/viewtopic.php?t=8796 - a good example of the psp gu power.
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[jean]

[gorim]

The PS2 had the closest thing to GPGPU of it time, and it wasn't really the GPU but rather the outboard VPU's (vector processors) that fed the GPU. But it worked on the same principle as todays programmable pixel engines and shaders - SIMD.

Regardless, the computing power is not there in either system (PS2 or PSP) to remotely do anything comparable to today's high end GPU's.

Now the GPU in the PS3, THAT would be a GPGPU monster, especially in conjunction with the SPU's, if only we could get at it. With the work being pioneered by those in the PS3 forums, that may happen eventually.

www.gpgpu.org is a good resource for gpgpu kinda things.
Also, the Nvidia book GPU GEMS 2 contains extremely good introductions.

[noxa]

[ufoz]

I don't see the point of trying to do number crunching on an underpowered handheld...?

If you just want a coprocessor or more parallelism in a game, the ME and VFPU are much more suited for that.

[jean]

just read topics instead of blindly-reply:

[adrahil]

Oh and all that of course without any display - since GE kind of is one of the only ways to access the display :)

TBH, I don't think you're talking about OCR or TTS... You're probably aiming at WEP&co :) Just forget it.

[gauri]

jean, I do not see any way to perform general purpose calculations on the fixed-function pipeline.
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[jean]

@adrahil

[ufoz]

[J.F.]

[jean]

What's the problem mr smart man? Do YOU are a REAL developer? Do YOU have a realistic goal? Then go for it! (and don't annoy me: all of your replies to me are simply pointless)
GPGPU _IS NOT_ something you CAN do ONLY if you have beefy hardware, BUT a trick to speed up things when you DON'T HAVE IT.
I would have never told that giving an advice to people who are in the position to turn it in practice could take to a rain of sarchastic posts like "it's not gonna happen" from people who demonstrated that they definitely DON'T KNOW what they are speaking of.
IF someone of you where minimally aware of what i'm saying, then he would have told me something technical about the GU_TCC_RGB constant as a parameter to sceGuTexFunc, the ONLY wrong thing i see to implement something good and that forces me to 8bit only. I expected people talking about GU_PSM_T16 and GU_PSM_T32 formats, or sceGuDrawBuffer... and not merely showing their posts-count. So, if someone is really interested in an open dialog, then PM me, as i see good ideas are not wellcome here.

[Wally]

[jean]

@wally
Finally a person I can talk with! Thanks for your care.
I wished to write a demo, but my time was sooo small...so i gave my idea to the community...who didn't appreciate it. After all, the criticisms had the effect to push me into the challenge and try to code something.
Let's do this way: i'll bet a beer.
If someone can help me figure out how i can draw 16bit textures on 16bit textures (obviously in hw accel.) avoiding the sum-and-saturate effect on the components (does something like GU_TCC_SINGLECOMPONENT exists?), THEN i will prove usefulness of the system OR i will pay a beer to all the criticists (of course they have to come visiting me in my country to have their beers).

take it easy....

jean

[Wally]

Im not your guy, I can barely program :P

but yeah im sure all the other devs have projects and are not up anything like this. hence all this tension :)

[J.F.]

He was talking to me, Wally, and generally demonstrating what an ass he is. If he doesn't even know what I've done, he certainly hasn't bothered searching/reading enough threads here to be yammering about anything.

@jean: Put your money where your mouth is - write something USEFUL for the PSP using GPGPU and I'll apologize. As it is, my opinion is based on the fact that using GPGPU on anything less than a nvidia 8000 series card on a beefy PC is worthless. Look at the GPGPU examples currently out - the recommended MINIMUM system is a beefy PC with TONS of memory and at least a 7000 series nvidia. The PSP doesn't even come close to those specs.

[jean]

[jbit]

Drama, if it continues the thread will be locked, and maybe hall of shamed depending how hilarious it is.

'GPGPU' sounds fun on PSP, I did some on PS2 for interpolation of some 8bit values and it was incredibly fast, but I never found a way to work it into my pipeline nicely.

I think to most people actually doing 'GPGPU' stuff the 'General Purpose' bit just means non-graphics, or at least non-raster-output stuff, and not that you can use it for anything under the sun...

Clearly any GPU that can render to non-onscreen RAM can be used to do things other than rasterising triangles, blitting sprites, etc and may be lots faster than a CPU at doing certain (very specific things).

Feel free to continue this thread in a constructive manner...

[tacoSunday]

[tacoSunday]

Oops, sorry jbit. that wasn't very constructive. Ill shut up now...

[jean]

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if you're not interested in anything else than PSP-programming-related arguments, please skip until the more constructive argument.
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[jimparis]

What are you actually trying to do? What operation?
It's hard to offer specific advice about how to use the GPU or ME or VFPU effectively to speed up calculations when it's not even clear what you're trying to calculate.