[MPlayer-dev-eng] MPlayer Profiling

[Mike Melanson]

On Sat, 19 Jan 2002, Alex Beregszaszi wrote:

> It's not saved. Think about it, cpu timestamp counter isn't ordered to a
> process. It's general. my_profile.h uses rdtsc (read timestamp counter),
> so process switching makes false values for us...
> 
> If i'm right ;)

	It doesn't seem to be explicitly specified anywhere. I found an
Intel document detailing the quirks and caveats of the register:
  http://cedar.intel.com/software/idap/media/pdf/rdtscpm1.pdf
They mention a bunch of factors that can possibly affect profiling, but
context switching wasn't one of them. It's the first problem I thought
of. However, since this feature is used for such fine-grained profiling,
it's probably not supposed to make a big difference (i.e., if a
context switch happened in the middle of profiling, it would be very
obvious).

	Thanks...
-- 
	-Mike Melanson