Re: do_gettimeofday( ) precision?

[abhijit]

On Thu, 24 Jun 2004 12:13:11 +0530, abhijit <slashdev@xxxxxxxxx> wrote:
>
> 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?

ok. after reading up the source, i think xtime isn;t updated frequently and will
not have the required resolution :( so calling do_gettimeofday() seems the only
way out (unless somebody has any other idea).

btw why isn't do_gettimeofday( ) declared as "inline". so its bit
cheaper to call
especially where you are timestamping (say packets) often.

thanks
abhijit
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