Comment by ColdStream
5 hours ago
To bring up an almost three decade old debate, it would be fascinating to see the performance difference between PPC and x86 in software rendering. Probably mostly bandwidth limited at this point still.
PPC ended up being a brilliant design done mediocre, while x86 is a mediocre design done very well.
I don't know the details but I would imagine that the comparison would shift quite a lot over those years due to the rollout of SIMD features on both sides along with the other microarchitectural improvements. I'm not sure I would characterize PPC as being mediocre, I think the designers hit more or less the target they wanted even if the top line performance numbers weren't hands down higher than the contemporary x86 parts and it didn't have the shine of IA64. There's a reason we still fly PPC 750 variants in some critical systems. If you think back to that period Apple was moving from 68k (where they were both one of the biggest customers for the chips but also not enough volume to field a part competitive on desktop) to PPC where they were no bigger (maybe declining unit volume) but at least part of a stronger coalition of users. The group's interest diverged (no laptop roadmap) and I'm guessing Apple wanted to switch to x86 as early as 2002 and it just took a few years to get the company stabilized enough to make the jump.
Edit: It would be interesting to look at the software rasterizer and game engine problems in a modern context of big compute and superoptimizers and see what is possible. I'm guessing not much above what the hand-tuned code of the era got, but maybe significant in the context of doing these kinds of retro-ports on a small budget.