Re: do_gettimeofday( ) precision?

[abhijit <slashdev@gmail.com>]

On Wed, 23 Jun 2004 17:54:13 +0200 (CEST), Lukasz Michal Rak
<l.rak@elka.pw.edu.pl> wrote:

> I don't know the way how to do it, but I wonder about 
> precision of such mechanism (if any exists).

basically i want some counter w/ microsend resolution that fits into 32 bits.
couple of possible solutions come to my mind:

[1]  use TSC and convert it to microsec
[2] use get_timeofday( ) and convert to microsec
[3] use xtime variable directly and convert to microsec
(any other ways?)

conversion in [1] will be costly (a div involved). 
conversion in [2]/[3] can be done using bit operators. (usec|sec << 20)
but [2] will incur function call overhead which i'd like to avoid.

so is using xtime directly ok and reliable?

thanks
abhijit