Newsgroup: it.comp.hardware.video-3d
Titolo: la gpu di x360 [articolo]

molto interessante:
http://tinyurl.com/apx8t
piccolo sunto:
 the Xbox 360 GPU also acts as the system’s memory controller, much like the 
Northbridge in an Intel PC
 it only makes sense that ATI could possibly put together one of the best 
GDDR3 memory controllers in the world
 The bus between the CPU and GPU was characterized as unique and 
proprietary. Mr. Feldstein did let on that the bus could shuttle up to 22 
Gigabytes of data per second. Much like GDDR3, this would be a full duplex 
bus, or one that “goes both ways” at one time
 It is my own opinion that it is very likely that the CPU/GPU bus is very 
similar to the GPU/RAM bus as it was stressed to me by Mr. Feldstein that 
the CPU/RAM pathway was very free of any latency bottlenecks.
 The  10MB of Smart 3D memory that is currently being built by NEC will have 
an effective bus rate between it and the GPU of 2GHz. This is of course over 
3X faster that what we see on the high end of RAM today.
 Inside the Smart 3D Memory is what is referred to as a 3D Logic Unit. This 
is literally 192 Floating Point Unit processors inside our 10MB of RAM. This 
logic unit will be able to exchange data with the 10MB of RAM at an 
incredible rate of 2 Terabits per second. So while we do not have a lot of 
RAM, we have a memory unit that is extremely capable in terms of handling 
mass amounts of data extremely quickly. The most incredible feature that 
this Smart 3D Memory will deliver is “antialiasing for free” done inside the 
Smart 3D RAM at High Definition levels of resolution. (For more of just what 
HiDef specs are, you can read here. Yes, the 10MB of Smart 3D Memory can do 
4X Multisampling Antialiasing at or above 1280x720 resolution without 
impacting the GPU. So all of your games on Xbox 360 are not only going to be 
in High Definition, but all will have 4XAA applied as well.
 The Smart 3D Memory can also compute Z depths, occlusion culling, and also 
does a very good job at figuring stencil shadows. You know, the shadows in 
games that will be using the DOOM 3 engine, like Quake 4 and Prey?
Now remember that all of these operations are taking place on the Smart 3D 
Memory and having very little workload impact on the GPU itself. So what 
exactly will the GPU be doing?
 First off, we reported on page 2 in our chart that the capable “Shader 
Performance” of the Xbox 360 GPU is 48 billion shader operations per second. 
While that is what Microsoft told us, Mr. Feldstein of ATI let us know that 
the Xbox 360 GPU is capable of doing two of those shaders per cycle. So yes, 
if programmed for correctly, the Xbox 360 GPU is capable of 96 billion 
shader operations per second. Compare this with ATI’s current PC add-in 
flagship card and the Xbox 360 more than doubles its abilities.
 While most games are vertex shader bottlenecked, some others are pixel 
shader bottlenecked. When you combine the Xbox 360 Unified Shader Approach 
and its massive shader processing power, you end up with a GPU that is built 
to handle gaming content far beyond what we see today in terms of visual 
quality.
 Some of the global illumination effects you might have seen in years past 
at SIGGRAPH have been put into motion on the Xbox 360 GPU in real time.
 The Xbox 360 also makes using curved surfaces possible in-game, meaning 
that it can calculate the polygons from the proper curved surface math in 
order to draw it on your screen “correctly.” Much in line with this is the 
ability to do high order surface deformation. And if you are familiar with 
high order surfaces, you are likely familiar with what gamers and hardware 
enthusiasts commonly refer to as “LOD” or Level of Detail. Mr. Feldstein 
shared with us that the Xbox 360 GPU has some “really novel LOD schemes.” So 
we are thinking that the days of cars in the distance with pentagonal shaped 
wheels in new Grand Theft Auto titles is a thing of the past.
 ATI has implemented “lots” of their mobile power saving features in this 
Xbox 360 GPU. Clock gating is even more efficient in this chipset than what 
we were aware of being implemented in Mobility Radeons of the recent past.
 ATI took their Xbox 360 GPU project from the ground floor to a working 
piece of silicon in 2 years. It is obvious that that there is much more to 
this GPU than what is being shared with us here, but even considering just 
the features shared here, a 2 year project time seems amazing. This can 
easily be considered a ground breaking GPU in terms of 3D gaming regardless 
of platform.

 ha scritto nel messaggio 
news:nK3je.1411001$35.52...@news4.tin.it...
altro articolo interessante sui taroccamenti di sony sulle demo di ps3
Che giravano su DUE Cell.
Un'altra demo addirittura aveva la fisica calcolata da un server che si
occupava solo di quello.
L'articolo
http://gear.ign.com/articles/615/615521p1.html
E3 2005: Cell Processor Technology Demos
IBM takes a through a series of demos highlighting the Cell's processing
prowess.
May 17, 2005 - As part of its technical showings at E3 2005, IBM set up a
demo event showcasing the Cell processor. Created by Sony, IBM and Toshiba,
the Cell processor will be the heart of Sony's forthcoming PlayStation 3,
officially unveiled yesterday at its press conference.
IBM's presentation consisted of a set of computationally-intensive demos,
intended to show off the number-crunching power of the Cell's individual
processing units. Each Cell processor is made up of one PowerPC Processing
Element (PPE) and eight Synergistic Processing Elements (SPEs). The PPE is
in charge of feeding instructions to the eight SPEs, which are capable of
working individually on tasks without the need to reference the other SPEs.
In short, a single Cell processor is capable of running eight separate tasks
simultaneously at its full operational speed (3.2GHz in the case of the
demoed CPUs), plus whatever you can throw at the PPE.
The first demo we saw was a ray-traced landscape demo, which was also shown
at Sony's PlayStation 3 press conference yesterday. Height field data
acquired by LIDAR (light RADAR basically) was combined with a color overlay
taken via satellite imagery to create a realistic 3D rendering of the Mount
St. Helens volcanic area.
The key to this demo was that the imagery was ray-traced in realtime solely
via a pair of Cell processors. Instead of using a video card to display the
graphics (thereby limiting the "wow" factor), the Cell processors rendered
the image to a series of JPG images, which were then streamed to a standard
G5 tower over the network. Each image was rendered at 1280x720, creating a
720p high-definition scene of the area.
A switch allowed for turning on colored stripes that represented what each
SPE was rendering at any given moment, updated in realtime. As more complex
areas entered the view, the SPEs would dynamically scale how much of the
scene they were rendering so that the framerate stayed even (and solid)
throughout the demo.
The next demo was based on a new cloth simulation algorithm being worked
into Maya. Again using two Cell processors, the demo was able to run 16
separate simulations simultaneously. Each piece of cloth was defined by 300
vertices, but the real kicker with this demo is that the algorithm
incorporated self-intersecting physics, keeping the cloth from flowing
through itself. This sort of simulation is much more
computationally-intensive than simulating a cloth against another object.
Next up we checked out a set of blade servers, each set up with two Cell
processors. They weren't final design quite yet, but when finished they'll
sport a double-width size while still being able to keep the processors
quite cool. In fact, as the blades were open we could test the heat coming
off of them and it felt reasonably cool, cooler than many of our high-end
PCs back at the IGN offices. This bodes well for heat-issues, or more
correctly the lack thereof.
Lastly, we saw a demo of a network game with entirely server-side physics.
The goal here was to prove that a high-end server could run some of the most
computationally-intensive parts of a game, saving the client machines from
having to process what would wind up being redundant data. The demo featured
some huge mechs, large buildings and a couple tanks. As parts of an object
were fired upon, pieces of it would crumble off and collide and bounce with
surrounding objects. While it honestly wasn't the most impressive piece of
physics tech we've ever seen, the fact that it was all running server-side
was kinda neat.
That ended our demo time with the Cell processor. While a couple of the
demos were quite impressive, like the cloth and landscape demos, the coolest
part was actually seeing Cell processors up and running right in front of
us. Sure, we saw the same thing yesterday at the Sony press conference, but
in those cases the hardware was hidden. It's reassuring to actually see the
processors cranking out data right in front of our eyes.
-- Chris Roper

 Che giravano su DUE Cell.
In questo caso dovevi scrivere su it.comp.hardware.cpu :oP
Parliamo di schede video qui, non divaghiamo troppo con 'ste console ;o)
-- 
 PaRRoT from Linux (user #302069) |     L I N U X       .~.
AMD Athlon XP 1700+ @2406MHz      |     The Choice      /V\
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Gillette Mach 3 @Mach 3 Turbo     |     Generation     ^^-^^

 Parliamo di schede video qui, non divaghiamo troppo con 'ste console ;o)
dai, passato l'E3 saremo tutti più IT
poi lo so che interessano a molti ste info, te compreso
resisti per oggi ;)))
ciao


altro articolo di anand sulle gpu delle due console del momento:
http://www.anandtech.com/tradeshows/showdoc.aspx?i=2423
pare proprio che RSX sia -una- ( :P ) G70  potenziata (presumibilmente
con piu' pipelines grafiche e l'interfaccia FlexIO, 300 milioni di
transistor sono tanti...) prodotta in 90nm.
-- 
    (iao!!oai)                                    (ICQ: 10860566)
    //.aurizio
[WARNING!: togliete _nessuno_ per rispondere]
    Coloro che sono disposti a farsi togliere alcune liberta' 
essenziali per ottenere un piccolo, temporaneo senso di sicurezza
non meritano ne liberta' ne sicurezza. [B. Franklin]

altre info:
http://www.firingsquad.com/features/xbox_360_interview/images/01.PNG
 FiringSquad: You said earlier that EDRAM gives you AA for free. Is that 
2xAA or 4x?
ATI: Both, and I would encourage all developers to use 4x FSAA. Well I 
should say there's a slight penalty, but it's not what you'd normally 
associate with 4x multisample AA. We're at 95-99% efficiency, so it doesn't 
degrade it much is what I should say, so I would encourage developers to use 
it. You'd be crazy not to do it.
l'AA 4x costa in performance 1-5%
sticazzi!
 FiringSquad: How does Xbox 360 GPU compare in size to the RSX?
ATI: In terms of size, we're a bit smaller. Of course, I'm not sure if that's 
a good way to compare things, and to be honest I can't talk about the number 
of transistors for this design. Microsoft owns the IP and that has a lot to 
do with their cost model and all that sort of stuff. But we're a very 
efficient engine and we feel very good about our design. You know, the bang 
for the buck is awesome. The power of the platform [pauses] we're going to 
be the most powerful platform out there, we've got a lot of innovation in 
there, we're not just a PC chip.
I think the Sony chip is going to be more expensive and awkward. We make 
efficient use of our shaders, we have 64 threads that we can have on the 
processor at once. We have a thread buffer inside to keep the [inaudible]. 
The threads consist of 64 vertices or 64 pixels. We have a lot of work that 
we can do, a lot of sophistication that the developer never has to see.
:))))))))))))))
 FiringSquad: Do you know if it supports dual HD displays?
ATI: No it doesn't. I know the NVIDIA chip does, but that's only because PC 
products do. It doesn't seem to have a real use inside the living room, but 
maybe you differ with me on that.
FiringSquad: Well, on the Sony console, I think they're looking at 
applications that go beyond just a console in the living room don't you 
think?
ATI: Yeah I really think it's just an accident because, well you know, last 
summer they had to change their plans. They found out that Cell didn't work 
as well as they wanted to for graphics. Remember originally you had two or 
three Cell processors doing everything and then in August last year they had 
to take an NVIDIA PC chip. And as you know, all PC chips do this, and so it 
[dual HD display outputs] just came for free.
http://www.firingsquad.com/features/xbox_360_interview/default.asp
 

[dual HD display outputs] just came for free.
esattamente quello che dicevo, rsx prevede due schermi non perche'
sono due schede in sli ma semplicemente perche' e' una versione
leggermente potenziata di un normale chip da pc, quindi con due ramdac
e due linee video, come tutti i chip video da pc prodotti negli ultimi
anni.
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altre info:
ancora robba (ma quand'e' che esce qualcosa di nuovo per pc, che di
questi scatolotti che non vedremo minimo per sei mesi abbiamo gia'
parlato anche troppo? :)
qui c'e' uno schema dettagliato dell'architettura
http://www.gamespot.com/news/2004/04/30/screens_6095043.html?page=1
interessante, i tre core hanno una L2 unificata da 1mb, un po' piccina
viste le dimensioni del codice tipichie dell'isa PPC, viene dichiarata
una latenza di accesso alla l2 di 31 cicli ma non viene dichiarato se
e' il best oppure il worst case, tre processori che condividono la
stessa l2 tendono ad avere un bel po' di problemi di latenze quando
vogliono tutti e tre la stessa locazione...
qui altra lunghissima intervista con Feldstein (il ragazzo si deve
essere consumato le corde vocali da quanto ha parlato in questi
giorni... ;-)
http://techreport.com/etc/2005q2/xbox360-gpu/index.x?pg=1
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