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[Bug nptl/14717] Allow choice of clock source for calls to sem_timedwait() and pthread_mutex_timedwait().


http://sourceware.org/bugzilla/show_bug.cgi?id=14717

--- Comment #2 from Grotlek <grotlek at hotmail dot com> 2012-10-16 13:30:59 UTC ---
Accepted - I was inferring from the Debian man page for clock_gettime() - as
the "wall clock" time does change for DST. However, the issue does still apply
because the clocks used for programmatic threads are subject to change with the
race condition I described, even if DST isn't one of the factors that influence
it (the other three do, and those are directly stated by the man pages).

I'll paste the descriptions of the clocks from the man page here, as it does
add to the conversation.

---

Sufficiently recent versions of glibc and the Linux kernel support  the
 following clocks:

 CLOCK_REALTIME
        System-wide  clock  that  measures real (i.e., wall-clock) time.
        Setting this clock requires appropriate privileges.  This  clock
        is  affected by discontinuous jumps in the system time (e.g., if
        the system administrator manually changes the clock), and by the
        incremental adjustments performed by adjtime(3) and NTP.

 CLOCK_MONOTONIC
        Clock  that  cannot  be  set and represents monotonic time since
        some unspecified starting point.  This clock is not affected  by
        discontinuous  jumps  in  the  system  time (e.g., if the system
        administrator manually changes the clock), but  is  affected  by
        the incremental adjustments performed by adjtime(3) and NTP.

 CLOCK_MONOTONIC_RAW (since Linux 2.6.28; Linux-specific)
        Similar  to  CLOCK_MONOTONIC, but provides access to a raw hardÃâÂ
        ware-based time that is not subject to NTP  adjustments  or  the
        incremental adjustments performed by adjtime(3).

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