November 11, 2006
Like I said on previous post, there was at the same lecture a bonus presentation on PS3.
The presenter was, also from Sony London Headquarters, but currently consultant of Sony PS3 Programming on behalf of Sony worldwide, István Fábián (yes, the accents are correct). This is the guy working on the PS3 since the beginning, and has he said it: If there’s someone who is an expert in PS3, he’s the one [not very modest, one might think]. He his working on PS3 for 16 months.
Most of the presentation had to do with parallel programming and the need for parallelization due to the fact that single cores are reaching their limits. An example of this is the launch of duo core processors by Intel, and the quad core processor during thos month.
Some years ago, I heard we would have 10Ghz CPUs in our home by 2005… I don’t have one, do have one?
An explanation of the Flynn’s taxonomy followed. SIMD is the single core architecture, extended with MMX, MMX2, SSE1..4.
In this line of thought, PS3 has 8 cores (octo-core??), 9 Hardware threads and all cores are usable for generic computing tasks, developed by STI (Sony-Toshiba-IBM). It has 4 buses allowing a bandwidth each of 25Gb/s and a BlueRay disc reader also reading legacy formats like CD/DVD. Although most say BlueRay supports 50Gb, 25Gb per layer, the truth is the blue ray has 8 layers, each allowing 25Gb per layer which totals 200Gb os information per disk.
The CPU (with 8 cores as mentioned) [codenamed Cell] is a MIMD architecture, with a bus of 200Gb/s bandwidth connecting all cores and a bus of 25.6Gb/s bandwidth for each external devices. Each core has a local store and a memory controller. It seems to be the most flexible model and it works asynchronously. Each core follows a SIMD architecture and one of its cores runs the Operating System, which is not Linux but it is possible to run Linux on it.
PS3 allows various programming models, has a pre-emptive scheduling and allows user-defined scheduling policies. Features an advanced job queue algorithm, not presented due to NDA [non-disclosure agreement].
Benchmarks reveal PS3 has a performance gain of 15 times over current top-notch desktop computers. A curious fact and one of the non-intuitive stuff a programmer must remember when programming for PS3 is that it is so fast to compute stuff that is that when there are several calculations to perform and which one is needed is decided upon a condition, it is faster to compute them all and throw away the results which we don’t care about.
And that’s it… it was a nice presentation with the Sony guys… Still, I’m quite unhappy with Sony but I can’t deny I was impressed with PS3 hardware.