Sunday, December 13, 2009

Random thoughts on AMD's Fusion plans

More details have trickled out on AMD's Fusion plan since their announcement during their Financial Analyst Day. The new way they will be counting cores with Bulldozer certainly takes a bit of getting used to. I'm sure it will be a source of great confusion for a lot of people once 'Zambezi' is out.

As CPU/GPU integration efforts continue, I wonder if we'll one day be seeing a single 'CPU' core with multiple integer units the same way we're seeing GPUs with Stream Processors/Unified Shaders now.

If that comes true then we can expect massive improvements in integer performance I think. By then, all floating point operations would be delegated to the integrated 'GPU', or more specifically the on-die Stream processor (SP) clusters.

Looking even further into the future, we could be seeing a shift in thinking on how or what a processor looks like. Quite possibly we'll see the multi-core CPUs of today become a single 'parallel processor' the same way we're viewing multi-SP GPUs today as a single GPU. Instead of a single threaded CPU we'll have a massively parallel architecture with massive numbers of integer and floating point units.

The fact that Intel announced Larrabee's 'demise' made me wonder if AMD's plans didn't have anything to do with it. It's fairly 'obvious' that Larrabee's capabilities will not allow it to compete with AMD/nVidia offerings by the time it would have been released, so it all sounds just perfectly reasonable for Intel to make such an announcement.

I wouldn't be surprised if Intel shifted focus on maximising the performance of whatever GPU is in Westmere instead. At least they can try to minimise the gap. Two years is a long time and Llano may very well fall short of expectations yet. Just like Barcelona did. Maybe enough that Intel need not worry. But then again, they can't afford to wait to find out.

Suddenly the fact that AMD failed to acquire nVidia but had to settle with ATi doesn't look like a failure anymore. Their GPU business certainly is booming right now while nVidia is desperately trying to get back into the game. Both AMD and Intel are heading for CPU/GPU integration though likely in differing forms. In any case, we'll only see the beginnings of this future come 2011.

As for "Bulldozer" itself, appearances can be deceiving. Stating the 128-bit FPU is the "same one introduced in Barcelona" makes it sound like there's no improvement on the FPU front. There's just a tiny little fact to consider: either core can use both FPUs as a single 256-bit FPU is the other core isn't using it.

Considering that most applications are single threaded and will remain so for the foreseeable future, this would make "Bulldozer" run as a single core CPU with a 256-bit FPU surprisingly frequently. In any case, only time will tell just how effective this move will be.

For the consumer's sake, I hope AMD gets to kick Intel behind once more.