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[Bug nptl/14717] Allow choice of clock source for calls to sem_timedwait() and pthread_mutex_timedwait().
- From: "grotlek at hotmail dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: Tue, 16 Oct 2012 13:30:59 +0000
- Subject: [Bug nptl/14717] Allow choice of clock source for calls to sem_timedwait() and pthread_mutex_timedwait().
- Auto-submitted: auto-generated
- References: <bug-14717-131@http.sourceware.org/bugzilla/>
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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