During the debut of Windows 7 build 6801, Windows Engineering Chief Steven Sinofsky made a passing reference to Windows 7 being able to scale to 256 processors. But he never said how this would be enabled.
Mark Russinovich, Technical Fellow in Microsoft’s Core OS division, explained in more detail how Microsoft has managed to do this in a video interview published on Microsoft’s Channel 9 Web site.
Russinovich said that Microsoft has managed to break the dispatcher lock in Windows — a task that had stumped even the father of the Windows NT operating system, David Cutler. When Cutler designed Windows for the server, systems beyond 32-way seemed far, far away, Russinovich said.