Wednesday, August 23, 2006

The UNTOLD Reason why AMD will have to go with Native Quadcore

While Intel is releasing its quadcore soon (expecting Q42006), AMD will release its native version of quadcore in 2 or 3 quarter later than Intel. AMD (and its fan) also tried to play down Intel's non-native version, and claiming the native approach is better.

What people failed to realize what if AMD using Intel's approach before come out with the native version, the end result will be a Internally NUMA quad core, which is bad for mobile, desktop, or even as a NUMA node for the server MP. So, it is really not a matter native if better than not native for AMD, it is just that the non-native approach is NOT good for AMD.

Why bad? As of current (and foreseeable future), there is not much (if not any) apps get wriiten for the NUMA optimization. And most desktop/laptop apps doesn;t require that level of memory bandwidth (the NUMA has better bandwidth but with a catch - need software optimization that doesn't work in all workloads). NUMA is a sensible thing in server MP, not in desktop or laptop. Having 2 memory link also raise the system cost, making it unsuitable for cost concern market.

For mobile specifically, it is mainly driven by form factor, power and wireless. 1P is definetely as solution for it. Having NUMA within the 1P, it just means it need minimum of 2 dimm and might not be a good candidate for certain very small form factor mobile device. The unncessary memory bandwidth in most mobile application also causing the power to be up, while not gurantee significant improvement. (I'm not sure if certain apps would show negative improvement)

For server MP particulaly, if this internally NUMA chip is used as a NODE, there will be multiple node distance in the whole MP design, which again making the software optimization harder.