Technical Notes

Related Topics:

Reading the System Clock

NTP's sys_fuzz_nsec is the time it takes to read the clock in nanoseconds (it's an integer type), and sys_tick is the same thing in a floating type but in usec. sys_precision is log2 of sys_tick.

Some systems have clock_getres() and it behaves differently on different OSes. NTP generally uses CLOCK_REALTIME for its operations, but on some OSes that value will not give use the information we want:

OS	sys_fuzz_nsec	sys_tick	CLOCK_REALTIME	Other
FreeSBD7	1676	1.676	280
Solaris10	916	0.916	1000000	83 CLOCK_HIGHRES