[DavidBuchanan]

> The main issue with RDTSC is that task-switches may cause your thread of execution to change cores or mess up your timing

I got around this by running my benchmarks in a kernel module, with interrupts disabled. Obviously this is only possible under certain circumstances.

I also disabled caching via the CR0 register for maximum repeatability, although of course that isn't at all reflective of "real world" performance, so it depends on what you're actually trying to measure.