[oppositelock]

Haha! I've spent months tuning code to run on the Cell, and I despise that thing.

Sony gave you 6 of the 8 SPE cores to use (I think they reserved two, but it's been ages). They are indeed very fast, however, they have no cache coherent access to main RAM and only 256k of memory for each element. So, you have to meticulously write DMA scheduling code to keep them fed. If you're a simpleton like me, you double buffer your SPE memory, cutting in in half, so 128k to work with, 128k for paging into, and you hope to be done paging before it's needed. Latency to memory is on the order of 2,000 cycles to first byte, but then they arrive fast.

So, what you do is decompose your problem into data streams that can be cruched through, but in such a way that you minimize the need to randomly access much memory. It's often cheaper to recompute things locally than to fetch them from RAM. Random access into your RAM is pointless, so you have to marshal all your input into DMA buffers, do some work, marshal all your output into other DMA buffers, and send back to host CPU.

Anyhow, I got this working. Meshes were being skinned at very high rate, but it was very frustrating. The PPE was really slow, so you had to offload as much as you could to those SPE's. But hey, I may be complaining, but it sure beats dealing with the "Emotion Engine" on the PS2. I can tell you which emotion that engine brings up.

[kevml]

In the early years, the SPUs were not all functional due to the fabbing process. The ones that had all 8 functional ended up in servers, and the ones with about 6 ended up in PS3s. This still happens all the time with clock speeds, and core counts on modern processors today. I’m sure the fabrication process improved over time, but they disabled the 2 cores to maintain backwards compatibility.

Unrelated: Every time I’m reminded about Cell I’m reminded of the OtherOS fiasco. I purchased a PS3 for the processor solely and I was very upset when I only got a $2 check for it. I never cashed it.

[CoastalCoder]

Same for me. I was very angry that Sony got away with that.

[halfsquatch]

I still have a launch-edition PS3 on firmware 1.01 that I got on launch day (wife and I were fortunate enough to be able to buy two and stash one). I've lost all kinds of stuff in moves and etc. since, but that thing will have to be pried from my cold dead hands.

[djmips]

Sounds like you learned a lot and are a better programmer from it. Pretty much everything hasn't changed and you can either hope Moore's law bails you out somehow or you can take what you have learned and apply that to the reality of whatever hardware you happen to be optimizing, CPU or GPU. Sorry it's painful but to eke out max performance it's going to be hard at times.