is the resolution of do_gettimeofday in usec?

[wael showair <showair2003@yahoo.com>]

Hi All,
i have board that contains MPC8555 processor with linux 2.6.27 ported to it.
i want to use an accurate function to measure the time. i searched the
kernel code & i found several functions but i read that the do_gettimeofday
is the most accurate one since it has a timer resolution of usec.

my question is how this function give this accuracy while the kernel timer
is 4msec?
is this a real accuracy or does it convert from msec to usec?
or does it depend on another timer counter that has this resolution?
or may b it measure the clock cycles of the processor within certain
interval?

Note that the freq of the processor is 850MHz.

Unfortunately, the function is implemented in assembly & i cant understand
it?
so can u tell me how this accurate numbers can be got or they r just fake
numbers?

thanks
-- 
View this message in context: http://www.nabble.com/is-the-resolution-of-do_gettimeofday-in-usec--tp23807779p23807779.html
Sent from the linuxppc-dev mailing list archive at Nabble.com.