I believe they're rolling out reverse hyperthreading when they do the on-die memory controller.
There is not point implementing "reverse hypertherading" it is a total waste of die space that could be *far* better used for something else.
Sure it is a nice dream, but by 2008 most developers (with a clue) will be making heavily threaded applications designed for multi-core systems.
There is absolutely no point implementing "reverse hyperthreading" in 2008.
It isn't technically impossible, but it is far more difficult than most people think to combine multiple CPU pipelines, registers, etc into one 'logical' pipeline for the 'minority of software' (given the 2008 timeframe).
Anything that isn't threaded by then is unlikely to require threading to give decent performance, or just simply would not scale (other bottlenecks).
I've thought about how cool it would be, so I did some research on it, the educated conclusion in every case was that it was a waste of a large portition of die space that could go to cache, more cores, and/or other features.
Intel Xeon 5100 systems use a dual 1333 FSB, typically with larger caches and get more utility (via prefetching, etc) out of their 'slower' interface to RAM.
AMD Opteron 200/2000 systems use ccNUMA and can aggregate the performance (I used to run an Opteron 270 with ccNUMA it was alright), but the smaller caches in many applications let to lower utility of the higher FSB (nTune has a FSB throughput indicator).
The AMD system typically got around 70% utilisation of its 'FSB' (for lack of a better definition, but anyone reading this knows what I mean).
The Intel system typically got around 83% (give or take) of its dual FSB.
Sure when cache hit rates get low the Opteron scaled better, but since cache hit rates are usually in the order of 60%+ in most tests the Intel rig comes out on top. Not always by a large margin, and in some very intensive tests the Opteron comes out on top.
Price and Longtivity (FB-DIMMs will scale to higher density than Reg ECC DDR2 DIMMs) the Intel system usually wins out. (Then bear in space, power consumption, performance ber cubic foot, etc).
However I'll admit it is a close race, and AMD don't need to add a 4th pipeline to get back into the lead, esp in 8-way (8 core) and above systems.
Bear in mind currently 2 of my 3 systems are AMD, as even I will be transitioning gradually.
- Turion 64 laptop (Only x64 mobile on the market at the time, Core Duo was not established and only x86-32, and Pentium M didn't look as cost effective)
- AMD Athlon 64 X2 - 2.4 GHz, 2 x 512 KB L2 cache, Dual-Ch DDR2-800
- Intel Core 2 Duo E6600 - @ 3.0 GHz / 1333 FSB. Also decked out.
I like to keep a 45/45/10 or 40/40/20 balance (Intel / AMD / Other + Mobile) using budget and performance/dollar as my 'splitter'.