On Saturday, February 19, 2011 7:04:01 AM UTC-6, Bob Masta wrote:
> I seem to recall finding that QueryPerformanceCounter
> returns results similar to RDTSC on XP and later.

I just stepped through the assembly code generated in Windows XP and Visual Studio 2008.  The function makes a call into the OS with SYSENTER, and returns with the values in registers.  It also goes through several indirect layers of calling to get there.

- Rick C. Hodgin