Fastest timecounter ?

[Joseph Koshy]

vg> I wrote a piece of software that has to get the current
vg> timestamp, one way or the other, a huge number of times per
vg> second. Apart from the empyrical tests one can perform to
vg> find out the timekeeping scheme with the less performance
vg> impact, is there any rule of thumb as to what choice to go
vg> for ?

vg> Any kind of advice is most welcome, especially reading
vg> material.

vg> P.S. I know that some of you may say that calling
vg> gettimeofday() that often is braindead, and at some
vg> point I agree. Unfortunatley, right now I can't do
vg> anything better. I need timekeeping to comb the
vg> algorithms that deal with my data structures a bit more,
vg> after which I can switch to time-related optimizations.

If you just want a relative count (i.e., not absolute
time) and if your machine's aren't going to be in sleep
modes, you could use the RDTSC instruction directly.

--
FreeBSD Volunteer,     http://people.freebsd.org/~jkoshy