[vox-tech] Easiest way to calculate date in 100 ns increments?
Rick Moen
rick at linuxmafia.com
Wed Jun 23 15:28:41 PDT 2004
Quoting Mark K. Kim (lugod at cbreak.org):
> Having said that, `date` is a nice tool for converting from human readable
> format to hour/minute/sec/nanosec if you're scripting, and the source is
> freely available if you're using C!
Most likely, the results wouldn't be meaningful since the querent is
looking for 100 ns resolution. I believe that date uses gettimeofday,
which is at best accurate to about two microseconds. It'd be a
challenge to converge in 100 ns accuracy with a suitable algorithm --
under rather rare conditions, I would think. I used to know how to do
this, but that would have been in structured Fortran. ;-> [1]
If you need 100 ns resolution, therefore, it's better to use something
like Robert G. Brown's nanotimer utility, which reads and uses
information from the on-board cycle counter accessible on pretty much
all modern CPUs. See:
http://www.beowulf.org/pipermail/beowulf/2004-January/009028.html
[1] No, that language is not dead; it just smells that way. Quit
sniggering, sonny, or I'll whack you with my cane.
--
Cheers, "A raccoon tangled with a 23,000 volt line, today. The results
Rick Moen blacked out 1400 homes and, of course, one raccoon."
rick at linuxmafia.com -- Steel City News
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