[Bug libgomp/47854] New: omp_get_wtime documentation incorrect

[Bug libgomp/47854] New: omp_get_wtime documentation incorrect

[jb at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47854

           Summary: omp_get_wtime documentation incorrect
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libgomp
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: jb@gcc.gnu.org


The implementation of omp_get_wtime() uses clock_gettime(CLOCK_MONOTONIC, ...)
if available (which IMHO is the correct choice). However, the documentation
(e.g. http://gcc.gnu.org/onlinedocs/libgomp/omp_005fget_005fwtime.html ) states
that "On POSIX compliant systems the seconds since the Epoch (00:00:00 UTC,
January 1, 1970) are returned.". For CLOCK_MONOTONIC, this is incorrect, as
POSIX 2008 only states

http://pubs.opengroup.org/onlinepubs/9699919799/functions/clock_gettime.html

"If the Monotonic Clock option is supported, all implementations shall support
a clock_id of CLOCK_MONOTONIC defined in <time.h>. This clock represents the
monotonic clock for the system. For this clock, the value returned by
clock_gettime() represents the amount of time (in seconds and nanoseconds)
since an unspecified point in the past (for example, system start-up time, or
the Epoch). This point does not change after system start-up time. "

And indeed, at least on Linux 2.6.32, that starting point is not the epoch.

[Bug libgomp/47854] omp_get_wtime documentation incorrect

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47854

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-02-23 08:58:19 UTC ---
Author: jakub
Date: Wed Feb 23 08:58:16 2011
New Revision: 170434

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=170434
Log:
    PR libgomp/47854
    * libgomp.texi (omp_get_wtime): Don't say time in the past
    must be Unix Epoch.

Modified:
    trunk/libgomp/ChangeLog
    trunk/libgomp/libgomp.texi

[Bug libgomp/47854] omp_get_wtime documentation incorrect

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47854

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |jakub at gcc dot gnu.org
         Resolution|                            |FIXED

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-02-23 09:10:59 UTC ---
Fixed.