CVSROOT: /cvs
Module name: src
Changes by: [email protected] 2019/10/26 15:16:38
Modified files:
sys/kern : kern_time.c kern_tc.c
sys/sys : timetc.h
Log message:
clock_getres(2): actually return the resolution of the given clock
Currently we return (1000000000 / hz) from clock_getres(2) as the
resolution for every clock. This is often untrue.
For CPUTIME clocks, if we have a separate statclock interrupt the
resolution is (1000000000 / stathz). Otherwise it is as we currently
claim: (1000000000 / hz).
For the REALTIME/MONOTONIC/UPTIME/BOOTTIME clocks the resolution is
that of the active timecounter. During tc_init() we can compute the
precision of a timecounter by examining its tc_counter_mask and store
it for lookup later in a new member, tc_precision. The resolution of
a clock backed by a timecounter "tc" is then
tc.tc_precision * (2^64 / tc.tc_frequency)
fractional seconds.
While here we can clean up sys_clock_getres() a bit.
Standards input from guenther@. Lots of input, feedback from
kettenis@.
ok kettenis@
