Re: nanosleep() uses CLOCK_MONOTONIC, should be CLOCK_REALTIME?

[Roman Zippel <zippel@linux-m68k.org>]

Hi,

On Mon, 23 Jun 2008, Michael Kerrisk wrote:

> >> Is there a reason to use CLOCK_MONOTONIC, instead of CLOCK_REALTIME?  Is it
> >> intentional?  If yes, then I should document this in the man-pages.  If not,
> >> then it should be fixed.
> >
> > CLOCK_MONOTONIC works fine even if ntpd steps the clock forward or
> > backward, CLOCK_REALTIME not. So the man page should be fixed.
> 
> Thanks for your reply, but I'm not quite convinced yet.  The things
> is: the Solaris man page also says "CLOCK_REALTIME".  (Of course that
> man page may just be parroting the standard.)  Could there not be some
> reasonable semantics for a nanosleep() that was based on
> CLOCK_REALTIME?

CLOCK_MONOTONIC is optional, that's probably the reason it's not mentioned 
there. If you check the man page for clock_settime, it specifically 
mentions that pending relative timer (including nanosleep) aren't affected 
by the changed time, thus if CLOCK_MONOTONIC and CLOCK_REALTIME advance 
equally, it doesn't matter which you use for relative timer.

bye, Roman