I recently completed an installation of Windows Server 2008 R2 RTM 64 bit on a computer on my home network. I am interested in how R2 balances loads across a Quad-Core processor such as the AMD Phenom X-4 9650 2.30 GHz. My first test was to use Winrar to extract an extremely large file to my hard disk. The extraction took ten minutes and the average CPU Usage was 25%. Despite the fact that the AMD is really a workstation CPU and not designed for use on a server the workload was balanced fairly equally among all of the cores.
Next, I installed the Hyper-V role (the Phenom with AMD-V supports hardware assisted virtualization, a requirement of Hyper-V) and built a virtual machine of Windows 7 64 bit. While running the Windows 7 VM the CPU loads were well balanced across all four cores as I launched multiple applications in rapid succession. Even a large file copy process within the virtual machine was balanced nearly perfectly.
The computer is a dual- boot machine with Windows Vista Home Premium Edition 64 bit installed on another partition. I decided to do a very, very, unscientific comparison of the two operating systems use of physical memory. When booted into Vista, Task Manager shows Physical Memory usage of 1.55 GB while running WordPad, Calculator, and Acrobat Reader 8. Server 2008 R2 uses 1.19 GB with the same workload. This comparison is not completely fair as Vista was running Sidebar with the newsfeed reader gadget. However Server was a Domain Controller and a Global Catalog Server and was also running SQL Server Express! I would be interesting to run the two with the same exact workload and compare resource usage. It would be a little bit like taking a minivan and half-ton diesel pickup truck to a drag strip and seeing which would win a race.
What seems likely is that Windows Server 2008 R2 uses memory more efficiently than Window Vista and the performance improvements made to Windows 7 are shared by this version of Server. It is clear that AMD has worked closely with Microsoft to optimize their Quad-Core processors on the new Windows OS. Check out a weblog post by Margaret Lewis of AMD here.