Windows Server 2008 R2 represents the latest evolution of the Windows Server operating system and corresponding support for high-end hardware systems with large numbers of microprocessors.  The 64-bit versions of Windows 7 and Windows Server 2008 R2 support more than 64 Logical Processors (LP) on a single computer.

Microsoft has tested R2 with 256 processor systems; the largest systems available at present.  New commodity computer systems will soon appear that leverage NUMA architectures.  A system with 4 CPU sockets, 8 processor-cores per socket and with Simultaneous Multi-Threading (SMT) enabled per core, will readily achieve 64 Logical Processors.  

R2 features enhanced support of Non-Uniform Memory Access (NUMA) computer architectures along with new User-Mode Thread Scheduling (UMS) technology.    UMS enables custom thread-level scheduling within your own application.   For certain categories of computing scenarios, this avoids the overhead of kernel transitions and context switching.  New API's are available for both NUMA and UMS technologies.  

Many high-end multi-core server-class software solutions may now be developed with NUMA and/or UMS integration in order to achieve linear performance scaling.  Parallel Computing and High Performance Computing solution developers may find NUMA awareness essential for performance scalability.

Both .NET and C++ developers will appreciate how these new platform capabilities are extended via libraries such as the C++ Concurrency Runtime and the .NET Parallel Extensions along with complementary tools support within Visual Studio 2010.

Learn more about platform scalability and NUMA API's at MSDN Channel9 and see extensive documentation at the MSDN Library.   Check-out the Native-Concurrency blog.