Why Windows Server 2003 for Opteron is significant

My colleague John Fontana reported last week that Microsoft has released a public beta of Windows Server 2003 for AMD’s Opteron processor. While a 64-bit version of Windows Server software isn’t “breaking news” (Windows 2000 came in a 64-bit version), a version tuned for a non-Intel chip is significant.

Traditionally, 16-bit CPUs from AMD and others emulated the Intel 16-bit instruction set so that they appeared (to the software) to be an Intel chip. The advantage of the non-Intel packages was price, speed or lower power consumption. But the Opteron changes that. While 32-bit CPUs varied a tad from this formula, there were still, essentially, transparent clones of the Intel chips as far as application software was concerned.

While a Windows Server 2003 version for Intel’s 64-bit Itanium chip has been available for many months, Microsoft needed much more time to ensure that the server operating system was taking full advantage of the benefits of the Opteron. Specifically, the difference is most noticeable in running older 32-bit applications. Since there are few 64-bit apps on the market as yet, most of what you run on your servers is 32-bit code. And, as Fontana reported, the Opteron runs 32-bit code faster than Intel’s Itanium.

When Intel designed the Itanium, it re-architected the code from the ground up to optimize 64-bit performance. In doing so, Intel needed to include an emulation layer for 32-bit software. AMD took a different approach, keeping the bulk of the 32-bit instruction set and wrapping a 64-bit architecture around it.

The difference is that the Opteron executes 32-bit code in native mode while the Itanium must first pass it through the emulation layer. While I haven’t seen any good independent benchmarks (there’s some information at the AMD site: https://www.amd.com/us-en/Processors/ProductInformation/0,,30_118_8796_8800%7E78187,00.html), the differences should be noticeable to you in your testing environment.

Now the software Microsoft released last year when Windows Server 2003 first shipped will work on an Opteron-based platform, it’s just that the new software is tuned to the CPU so that it will run much more efficiently – and a lot faster.

Whether or not the Opteron, the Itanium or something else will work best with 64-bit applications is merely speculation at this point until there are enough 64-bit software apps available for a true test. But in the meantime, you can improve the performance of your server-based 32-bit applications which might mean fewer phone calls of the “why is the network so slow?” type from users (or, even more importantly, from your boss). Head over to https://www.microsoft.com/windowsserver2003/64bit/extended/trial/default.mspx for all the details on this trial version and do remember that this is beta software – it’s not feature-complete yet and shouldn’t be used in a production environment. But it is fun to play with.