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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2020-04-11 13:32:29 +0200 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2020-04-11 21:34:51 +0200 |
| commit | 0953c1b4b3b4b3b44388de57e4d6a2be5150b60c (patch) | |
| tree | 7f360c7b39163229ca5678a1c6e7efc78752bf6a /man7 | |
| parent | 3685736f10e82b57f8a19cfe13f8fc3f82ee23a7 (diff) | |
| download | man-pages-0953c1b4b3b4b3b44388de57e4d6a2be5150b60c.tar.gz | |
time_namespaces.7: Tweaks for symbolic clock-IDs in /proc/PID/timens_offsets
Andrei Vagin implemented a change I suggested:
clock-IDs are now be expressed in symbolic form (e.g.,
"monotonic") instead of numeric form (e.g., 1) when reading
/proc/PID/timerns_offsets, and can be expressed either
symbolically or numerically when writing to that file.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Diffstat (limited to 'man7')
| -rw-r--r-- | man7/time_namespaces.7 | 35 |
1 files changed, 25 insertions, 10 deletions
diff --git a/man7/time_namespaces.7 b/man7/time_namespaces.7 index 656f365c90..3f82fcb927 100644 --- a/man7/time_namespaces.7 +++ b/man7/time_namespaces.7 @@ -95,10 +95,14 @@ three space-delimited fields: .PP The .I clock-id -identifies the clock whose offsets are being shown. -This field is either 1, for +is a string that identifies the clock whose offsets are being shown. +This field is either +.IR monotonic , +for .BR CLOCK_MONOTONIC , -or 7, for +or +.IR boottime , +for .BR CLOCK_BOOTTIME . The remaining fields express the offset (seconds plus nanoseconds) for the clock in this time namespace. @@ -117,8 +121,8 @@ file are as follows: .in +4n .EX $ \fBcat /proc/self/timens_offsets\fP -1 0 0 -7 0 0 +monotonic 0 0 +boottime 0 0 .EE .in .PP @@ -193,6 +197,17 @@ clock. Virtualization of this clock was avoided for reasons of complexity and overhead within the kernel. .PP +For compatibility with the initial implementation, when writing a +.I clock-id +to the +.IR /proc/[pid]/timens_offsets +file, the numerical values of the IDs can be written +instead of the symbolic names show above; i.e., 1 instead of +.IR monotonic , +and 7 instead of +.IR boottime . +However, writing +.PP The motivation for adding time namespaces was to allow the monotonic and boot-time clocks to maintain consistent values during container migration and checkpoint/restore. @@ -248,8 +263,8 @@ clock forward 7 days: .in +4n .EX $ \fBPS1="ns2# " sudo unshare \-T \-\- bash \-\-norc\fP -ns2# \fBecho "1 $((2*24*60*60)) 0" > /proc/$$/timens_offsets\fP -ns2# \fBecho "7 $((7*24*60*60)) 0" > /proc/$$/timens_offsets\fP +ns2# \fBecho "monotonic $((2*24*60*60)) 0" > /proc/$$/timens_offsets\fP +ns2# \fBecho "boottime $((7*24*60*60)) 0" > /proc/$$/timens_offsets\fP .EE .in .PP @@ -278,9 +293,9 @@ file produce an error. .in +4n .EX ns2# \fBcat /proc/$$/timens_offsets\fP -1 172800 0 -7 604800 0 -ns2# \fBecho "7 $((9*24*60*60)) 0" > /proc/$$/timens_offsets\fP +monotonic 172800 0 +boottime 604800 0 +ns2# \fBecho "boottime $((9*24*60*60)) 0" > /proc/$$/timens_offsets\fP bash: echo: write error: Permission denied .EE .in |