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: unassig...@gcc.gnu.org
ReportedBy: j...@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.
