cvs commit: src/sys/kern vfs_subr.c
phk at phk.freebsd.dk
Mon Sep 12 09:45:58 PDT 2005
In message <200509121240.51775.jkim at FreeBSD.org>, Jung-uk Kim writes:
>Please make sure to use `time_uptime' if you need monotonic timestamp.
>Especially many network stacks seem to make sequence IDs and
>timestamps to expire from `time_second' instead of time_uptime.
>time_second is not guaranteed to be monotonic! time_uptime is.
I would like to add that this is *also* true for userland
where uptime is called clock_gettime(CLOCK_MONOTONIC,...).
Please consider carefully, if you need a timestamp for a certain
time of day or just a certain inverval of time measured from now.
In the latter case, it is _always_ uptime/CLOCK_MONOTONIC you want.
Failure to do this means that your program/kernel code will do the
wrong thing when the clock is stepped (manually or by NTP).
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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