MICROTIME(9) | Kernel Developer's Manual | MICROTIME(9) |
bintime
, getbintime
,
microtime
, getmicrotime
,
nanotime
, getnanotime
—
#include <sys/time.h>
void
bintime
(struct bintime *bt);
void
getbintime
(struct bintime
*bt);
void
microtime
(struct timeval
*tv);
void
getmicrotime
(struct timeval
*tv);
void
nanotime
(struct timespec
*tsp);
void
getnanotime
(struct timespec
*tsp);
bintime
() and getbintime
()
functions store the system time as a struct bintime at
the addresses specified by bt. The
microtime
() and getmicrotime
()
functions perform the same utility, but record the time as a
struct timeval instead. Similarly the
nanotime
() and getnanotime
()
functions store the time as a struct timespec. The
structures are described in
timeval(3).
The bintime
(),
microtime
(), and nanotime
()
functions always query the timecounter to return the current time as
precisely as possible. Whereas getbintime
(),
getmicrotime
(), and
getnanotime
() functions are abstractions which
return a less precise, but faster to obtain, time.
The intent of the getbintime
(),
getmicrotime
(), and
getnanotime
() functions is to enforce the user's
preference for timer accuracy versus execution time. They should be used
where a precision of 1/HZ (e.g., 10 msec on a
100HZ machine, see
hz(9)) is acceptable or where
performance is priority.
The system realtime clock is guaranteed to be monotonically increasing at all times. As such, all calls to these functions are guaranteed to return a system time greater than or equal to the system time returned in any previous calls. Comparable functions exist to retrieve the time elapsed since boot; see microuptime(9).
microtime
() family of
functions is in sys/kern/kern_tc.c as a part of the
timecounter(9) framework.
The implementation of the time counter sources used by the timecounter(9) is machine dependent, hence its location in the source code tree varies from architecture to architecture.
May 13, 2013 | NetBSD 9.0 |