Dual-Core FAQ for Developers

[gkoch]

All, I'm an ex-IDS editor writing up a draft of an FAQ for developers about dual-core. (It's going to be posted on IDS.) So I thought I'd check in this newsgroup to see if there any burning questions about dual-core chips that you'd like to see answered by Intel experts? Anything is fair game... including desktop (here today) and laptop and server (both coming relatively soon). Thanks for sharing your thoughts!

Geoff (gkoch AT stanfordalumni DOT org)

[gkoch]

Well, I've trolled around a bit and come up with several questions from the developer community. Here's a sampling. And if anyone wants to take a stab at answering even a few of them, that would be great!

Q's:

Is Pentium-D intentionally crippled as to how much RAM it will support (2GB, 3GB)? Is the supposition about MMIO assigned by BIOS to the 3GB to 4GB range correct? Does OS make a difference? Will future dual cores have such limitation?

SuSE 9.3 is said to be the first OS recommended for AMD Dual Core. Pentium-D appears to run well (with just 2GB RAM) under RH EL4 64-bit, a rather expensive OS. Will future Intel dual core be supported only under expensive new OS releases?

What is time frame foreseen for Windows to have adequate support (NUMA scheduling, etc) for multiple socket dual core?

AMD dual core 2.2Ghz single socket is said to require 460W power supply, and mortality rate appears high. Will power supply and heat rejection problems be typical of dual core?

Will Intel support or oppose building MPI clusters of Pentium D? What will the economics be, given that most MPI clusters currently use 2 socket systems? With many customers demanding Windows 64-bit MPI clusters, will that be supported by Intel or AMD dual core? Is Intel hoping to delay demand for dual core clusters until they have had time to figure out whether they can satisfy it with dual socket dual core?

Will Windows 64-bit dual core systems be supported with multiple interconnect device MPI? Rumor says Intel will keep hands off for at least a year.

I would think the most significant question from a software developer's point of view is: what differences will software see between a dual core chip and a system with dual CPUs? Will low-level algorithms like spinlocks need to be tweaked like they did when HT was introduced? Will any of the non-guaranteed behavior of things like interlocked functions and speculative fetch invalidation change?

any code changes needed so that no unexpected buffer overflow? like those in 64-bit with 32-bit code compatibility but some unexpected long address or memory space which leads to unexpected buffer overflow?.... em.....maybe my english is not good enough to tell sorry about that

[gkoch]

And heres a bread and butter question that should be probably be answered, too:

Dual-core is interesting on the desktop. But why didnt Intel first implement threading in its server processor given that many server-based applications are already threaded?

[TimP]

Early Pentium-D platforms were delivered with a BIOS which doesn't support adding RAM in the empty slots. BIOS upgrade will fix that.