diff options
| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2012-04-25 13:02:36 +1200 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2012-04-26 09:12:59 +1200 |
| commit | 63f0f3d9b8644eb923926a7f1fd013ea2d432abd (patch) | |
| tree | 55fff4976947804c4cb8601414a2912de624026a | |
| parent | 5f04b9486b2a156a571cc4c31b2b91e995399242 (diff) | |
| download | man-pages-63f0f3d9b8644eb923926a7f1fd013ea2d432abd.tar.gz | |
clock_getres.2: Clarify difference between CLOCK_MONOTONIC and CLOCK_MONOTONIC_RAW
Note interactions of these two clocks with discontinuous
adjustments to the system time and NTP/adjtime(2).
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
| -rw-r--r-- | man2/clock_getres.2 | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/man2/clock_getres.2 b/man2/clock_getres.2 index 67713c7cd5..ed6fed92c0 100644 --- a/man2/clock_getres.2 +++ b/man2/clock_getres.2 @@ -29,7 +29,7 @@ .\" .\" FIXME: Linux 2.6.39 adds CLOCK_BOOTTIME .\" -.TH CLOCK_GETRES 2 2010-02-03 "" "Linux Programmer's Manual" +.TH CLOCK_GETRES 2 2012-04-25 "" "Linux Programmer's Manual" .SH NAME clock_getres, clock_gettime, clock_settime \- clock and time functions .SH SYNOPSIS @@ -128,13 +128,20 @@ Setting this clock requires appropriate privileges. .B 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 +.BR adjtime (2) +and NTP. .TP .BR CLOCK_MONOTONIC_RAW " (since Linux 2.6.28; Linux-specific)" .\" Added in commit 2d42244ae71d6c7b0884b5664cf2eda30fb2ae68, John Stultz Similar to .BR CLOCK_MONOTONIC , but provides access to a raw hardware-based time -that is not subject to NTP adjustments. +that is not subject to NTP adjustments or +the incremental adjustments performed by +.BR adjtime (2). .TP .B CLOCK_PROCESS_CPUTIME_ID High-resolution per-process timer from the CPU. @@ -227,7 +234,7 @@ On Linux, these clocks are not settable .\" See http://bugzilla.kernel.org/show_bug.cgi?id=11972 .SH "SEE ALSO" .BR date (1), -.BR adjtimex (2), +.BR adjtime (2), .BR gettimeofday (2), .BR settimeofday (2), .BR time (2), @@ -236,4 +243,4 @@ On Linux, these clocks are not settable .BR ftime (3), .BR pthread_getcpuclockid (3), .BR sysconf (3), -.BR time (7) + time (7) |