How can I learn about the number of cycles a processor instruction takes to execute?
Nor AMD not Intel gives that kind of information and RDTSC is not a precise any more.
Any hint will be welcome?
Well, take readings of the TSC before and after the
instruction you want to measure. Make sure you disable
all IRQs and run this under a single-task OS like DOS.
Since DOS does not know of SMP and SpeedStep, the
TSC should be very reliable, and noone will reschedule