Truespeed said:
And the PS3 does have 6 robust identical cores. Oh, you must be referring to the PPU which people abuse by running gameplay, AI, physics, sound, etc code on. The sole purpose of the PPU was to be a job scheduler to the SPU cores. Any other monumental task it was assigned was the error of the developer. As we've heard repeatedly, the PS3 only shines when you move your systems to the SPU's. That's where the gain is and games that don't do this are easily identifiable.
IAWTP. Also -- and I'm no PS3 programmer, but I've considered trying it out -- one of the biggest gains with these SPE's comes from SIMD (vector) instructions; you can check these out
here, but the general gist is that these cores are really good at fetching and crunching lots of data simultaneously, as opposed to a more linear approach. In short, this means much more algorithmic heavy-lifting when it comes to operations that can take advantage of vector operations. I'm not a PS3 programmer, but my guess is that a lot of the benefit we're seeing comes from 1) the people who know how to manage jobs, and 2) the people who know how to convert common game algorithms to vectorized instructions [when you think of games on a 3d mathematics level, it's probably not tough to see why vector instructions can do a lot]. When Carmack talks about more sweat and tears with PS3, my assumption would be that they've had to essentially refactor to the SPE's spec, and their team had to learn how to take advantage of vectorization among other things. Since compilers aren't really *there* yet when it comes to optimizing at a vectorized instruction level, it probably takes a lot of learning, experimentation and research.
Also, if I've misinterpreted this, *real* PS3 programmers -- please correct
