UPDATE - April 4, 2005

In an interview conducted March 31, Intel Desktop Platform Group manager Jeff Austin told Tom's Hardware Guide that hyperthreading technology will not be extended to future Itanium 2 processors, but that the possibility remains that future Itanium 2s may utilize another form of implicit multithreading. This particular form of non-explicit multithreading, stated Austin, has yet to be created. Up until March 31, Intel Corp. had declined comment on this issue.

Austin also stated that no plans currently exist to endow Pentium D dual-core processors with HT, although HT will continue to be featured prominently in the company's new multi-core Pentium Extreme Edition.

With regard to the future role of HT, Austin stated he still perceives a future for the technology at Intel beyond the short term, citing as much as a 25% performance gain on some tests involving server platforms. "For the amount of silicon space that's allocated to deliver that gain," said Austin, the cost of implementing HT is "effectively negligible."

Hyperthreading is not contingent upon software to explicitly instruct the processor as to how and where new threads begin and end. However both Austin and Intel spokesperson George Alfs argue that the benefits of HT will become more apparent as software developers learn to take advantage of them. The most obvious HT benefits can be realized today, states Alfs, by taking advantage of existing multitasking in operating systems such as Windows XP - by allocating single threads to single tasks. One look at Task Manager, argues Alfs, reveals the number of tasks that are available candidates for multithreading, including HT. "It just makes so much sense...certainly we can have products ready for that," says Alfs.

But if a multicore processor also included hyperthreading for each physical core - effectively splitting physical threads into further logical threads - would the operating system favor the physical or logical splits? The answer may not yet be evident, implied Austin, although as he tells us, "If there were an application able to run on two threads, and the operating system is multitasking capable, such as Windows XP, [the OS] certainly has the capability [to] take that application, schedule it on two of the four threads, and then go and schedule other activities on the other two threads that are available." This scheduling might come into play, projects Austin, if a compiler is operating on two threads of a dual-core HT processor, and two other threads are available for tasks such as virus scanning or e-mail.

What remains to be seen is how the operating system would pair off threads for the two-threaded tasks - whether to fork each application between both physical cores, or hyperthread each application within an exclusive core to itself.

Austin also offered the following clarifications to our story on multicore processors. The first 65 nm desktop processor due for shipping in the first half of 2006, currently code-named Presler , is not considered part of the Smithfield "family." Technically, said Austin, there is no "Smithfield family," nor will the Yonah notebook platform be related to Smithfield. One implication here is that Presler may not be given the "Pentium D" name, and an entirely new brand designation may be created for it.

Presler (for desktops) and Dempsey (for Xeon servers) are dual-processor packages previously referred to as "DP," as distinguished from "DC" (dual-core) packages. But Austin tells THG that Intel presently classifies multiple processor packages as multicore so long as they share the same pinouts. In our story, I referred to Dempsey as "not technically dual-core," a view still upheld by some engineers outside of Intel, though apparently contradicting Intel's current definition. Although previous announcements made it seem Intel was planning to package two Smithfield processors into one Presler package, Austin stated Presler's cores will not be related to Smithfield (Pentium D).

Austin added that we should clarify that Bensley and Glidewell are server and workstation platforms, respectively, that utilize the Dempsey processor. He also said that Intel's planned Lyndon business platform utilizing the 945 and 955X chipsets, will incorporate multiple ranges of processors, including existing Pentium 4 models as well as future Pentium Ds. Further, he clarified that Truland will be one platform that utilizes the Paxville processor, but that Tulsa is the processor to succeed Paxville, not the platform to succeed Truland. A platform name for Tulsa processors has yet to be determined.