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| author | Paul Eggert <eggert@cs.ucla.edu> | 2021-12-28 12:03:37 -0800 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2021-12-28 12:04:49 -0800 |
| commit | d45d16182d90c871b59582b4628b6e0e5f5a9ead (patch) | |
| tree | c1240e28bc495c24cebad1be14c1d96c3b001795 /doc | |
| parent | af4148ce0197502ce017418871da592bd7be5d91 (diff) | |
| download | gnulib-d45d16182d90c871b59582b4628b6e0e5f5a9ead.tar.gz | |
clock_getres: document portability issues better
* doc/posix-functions/clock_getres.texi:
* doc/posix-functions/timespec_getres.texi:
Document problems with timestamp resolution.
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/posix-functions/clock_getres.texi | 11 | ||||
| -rw-r--r-- | doc/posix-functions/timespec_getres.texi | 8 |
2 files changed, 18 insertions, 1 deletions
diff --git a/doc/posix-functions/clock_getres.texi b/doc/posix-functions/clock_getres.texi index 1381c4649c..e93e8b30f5 100644 --- a/doc/posix-functions/clock_getres.texi +++ b/doc/posix-functions/clock_getres.texi @@ -15,7 +15,16 @@ Portability problems not fixed by Gnulib: @item This function is missing on some platforms: Mac OS X 10.11, Minix 3.1.8, mingw, MSVC 14. + +@item +On many platforms, this function returns a value other than the clock +resolution of @code{clock_gettime}, i.e., the minimum distance between +differing timestamps. For example, on AIX 7.2 it returns 10 +milliseconds even though the clock resolution is 1 microsecond. +Conversely, on GNU/Linux it typically returns 1 nanosecond even +though the clock resolution may be greater. @end itemize The Gnulib module @code{gettime-res} is a partial substitute; it implements -the @code{CLOCK_REALTIME} functionality of @code{clock_getres}. +the @code{CLOCK_REALTIME} functionality of @code{clock_getres}, +and fixes the too-high resolution bug of platforms like AIX 7.2. diff --git a/doc/posix-functions/timespec_getres.texi b/doc/posix-functions/timespec_getres.texi index 89d3e6f16f..c18a3635ff 100644 --- a/doc/posix-functions/timespec_getres.texi +++ b/doc/posix-functions/timespec_getres.texi @@ -15,4 +15,12 @@ glibc 2.33, macOS 12, FreeBSD 13.0, NetBSD 9.2, OpenBSD 7.0, Minix 3.3.0, AIX 7. Portability problems not fixed by Gnulib: @itemize +@item +On some platforms, this function returns a value other than the clock +resolution of @code{timespec_get}, i.e., the minimum distance between +differing timestamps. For example, on GNU/Linux it typically returns +1 nanosecond regardless of the actual clock resolution. @end itemize + +The Gnulib module @code{gettime-res} is a partial substitute; it implements +the @code{TIME_UTC} functionality of @code{timespec_getres}. |