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NAME | DESCRIPTION | SEE ALSO | COLOPHON |
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proc_timer_stats(5) File Formats Manual proc_timer_stats(5)
/proc/timer_stats - timer statistics
/proc/timer_stats (from Linux 2.6.21 until Linux 4.10)
This is a debugging facility to make timer (ab)use in a
Linux system visible to kernel and user-space developers.
It can be used by kernel and user-space developers to
verify that their code does not make undue use of timers.
The goal is to avoid unnecessary wakeups, thereby
optimizing power consumption.
If enabled in the kernel (CONFIG_TIMER_STATS), but not
used, it has almost zero run-time overhead and a
relatively small data-structure overhead. Even if
collection is enabled at run time, overhead is low: all
the locking is per-CPU and lookup is hashed.
The /proc/timer_stats file is used both to control
sampling facility and to read out the sampled information.
The timer_stats functionality is inactive on bootup. A
sampling period can be started using the following
command:
# echo 1 > /proc/timer_stats
The following command stops a sampling period:
# echo 0 > /proc/timer_stats
The statistics can be retrieved by:
$ cat /proc/timer_stats
While sampling is enabled, each readout from
/proc/timer_stats will see newly updated statistics. Once
sampling is disabled, the sampled information is kept
until a new sample period is started. This allows
multiple readouts.
Sample output from /proc/timer_stats:
$ cat /proc/timer_stats
Timer Stats Version: v0.3
Sample period: 1.764 s
Collection: active
255, 0 swapper/3 hrtimer_start_range_ns (tick_sched_timer)
71, 0 swapper/1 hrtimer_start_range_ns (tick_sched_timer)
58, 0 swapper/0 hrtimer_start_range_ns (tick_sched_timer)
4, 1694 gnome-shell mod_delayed_work_on (delayed_work_timer_fn)
17, 7 rcu_sched rcu_gp_kthread (process_timeout)
...
1, 4911 kworker/u16:0 mod_delayed_work_on (delayed_work_timer_fn)
1D, 2522 kworker/0:0 queue_delayed_work_on (delayed_work_timer_fn)
1029 total events, 583.333 events/sec
The output columns are:
[1] a count of the number of events, optionally (since
Linux 2.6.23) followed by the letter 'D' if this is a
deferrable timer;
[2] the PID of the process that initialized the timer;
[3] the name of the process that initialized the timer;
[4] the function where the timer was initialized; and (in
parentheses) the callback function that is associated
with the timer.
During the Linux 4.11 development cycle, this file was
removed because of security concerns, as it exposes
information across namespaces. Furthermore, it is
possible to obtain the same information via in-kernel
tracing facilities such as ftrace.
proc(5)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.9.1 2024-05-02 proc_timer_stats(5)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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