Reverse Hyperthreading Coming Soon? . . .

AMDZone reports that has an article saying that reverse hyperthreading is possible on current AMD AM2 chips and that it will debut right after Conroe.

The article goes on to say that this feature will be enabled with just an MS driver and a BIOS change.

We have two observations:

1) We doubt this is going to even come close to doubling the capabilities of a dual-core AMD system running a single-threaded application. What this technology appears to do is make two CPUs look like one bigger processor, sort of like making two Intel chips look like an Itanium. It doesn’t parallelize anything: if the application can take advantage or more decoders or in-flight operations or simultaneous processes, great, if not, not.

Such a generic approach can hardly be optimized for specific apps (though perhaps apps can optimize their code eventually).

But then again, anything helps, but . . . .

2) If this is so easy, why can’t the same thing work for Intel chips, too? Not saying it has to work, or would work as well, or might need a different driver and/or BIOS tweak, but until we get a detailed explanation otherwise, one ought not exclude that possibility.

Even if there is a hardware reason built into the AM2 chips that would enable this, even in the worst case scenarios, it probably would take little to enable Intel chips, indeed, it would be surprising if next year’s Kentsfield didn’t have such a feature (provided it actually helps to more than a nominal degree).

What To Think?

This is one of those “you’ll find out soon enough” situations. Best guess is that one of two things will happen:

  • AMD will announce this, they’ll say it helps a few programs a lot, then in a day or two, some testing will disclose that that’s pretty much all it does, or
  • AMD will announce this, it actually does help more than help a few programs, but Intel duplicates the feat either immediately or fairly shortly thereafter.

    This smells like a stunt, at least for the short-term. Not that the concept might not yield real benefits down the road, but like x86-64 (or for that matter hyperthreading), this is going to need software aware of and optimized for the new environment.

    If this truly were an OMG, 50% or even 25% improvement, believe me, AMD would be loud and proud about this. They certainly wouldn’t be submitting itself to Intel’s Conroese water-torture routine, and if you think AMD is keeping this quiet just to spring a big surprise on Intel, well, first, the cat’s been out of the bag since April, and second, you’ve been watching too many movies and/or pro wrestling and/or fairy tales, but I repeat myself. Too many people outside of AMD would have to know about this, and people talk.


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