diff options
| author | SeongJae Park <sj@kernel.org> | 2022-01-14 14:10:11 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-01-15 16:30:32 +0200 |
| commit | 995d739cde879a35ef6e890ecf80226b605ad36c (patch) | |
| tree | 7a164f141896f627a3f49cd32b2b9a3e37ebfb88 /Documentation | |
| parent | 4492bf452af532493b6591d2e090a0f8f7c11674 (diff) | |
Docs/admin-guide/mm/damon/usage: update for kdamond_pid and (mk|rm)_contexts
The DAMON debugfs usage document is missing descriptions for
'kdamond_pid', 'mk_contexts', and 'rm_contexts' debugfs files. This
commit adds those.
Link: https://lkml.kernel.org/r/20211209131806.19317-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/mm/damon/usage.rst | 52 |
1 files changed, 49 insertions, 3 deletions
diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst index 846c85bf4b9d..cb614c84ba9e 100644 --- a/Documentation/admin-guide/mm/damon/usage.rst +++ b/Documentation/admin-guide/mm/damon/usage.rst @@ -38,9 +38,9 @@ DAMON provides below three interfaces for different users. debugfs Interface ================= -DAMON exports five files, ``attrs``, ``target_ids``, ``init_regions``, -``schemes`` and ``monitor_on`` under its debugfs directory, -``<debugfs>/damon/``. +DAMON exports eight files, ``attrs``, ``target_ids``, ``init_regions``, +``schemes``, ``monitor_on``, ``kdamond_pid``, ``mk_contexts`` and +``rm_contexts`` under its debugfs directory, ``<debugfs>/damon/``. Attributes @@ -273,6 +273,52 @@ the monitoring is turned on. If you write to the files while DAMON is running, an error code such as ``-EBUSY`` will be returned. +Monitoring Thread PID +--------------------- + +DAMON does requested monitoring with a kernel thread called ``kdamond``. You +can get the pid of the thread by reading the ``kdamond_pid`` file. When the +monitoring is turned off, reading the file returns ``none``. :: + + # cd <debugfs>/damon + # cat monitor_on + off + # cat kdamond_pid + none + # echo on > monitor_on + # cat kdamond_pid + 18594 + + +Using Multiple Monitoring Threads +--------------------------------- + +One ``kdamond`` thread is created for each monitoring context. You can create +and remove monitoring contexts for multiple ``kdamond`` required use case using +the ``mk_contexts`` and ``rm_contexts`` files. + +Writing the name of the new context to the ``mk_contexts`` file creates a +directory of the name on the DAMON debugfs directory. The directory will have +DAMON debugfs files for the context. :: + + # cd <debugfs>/damon + # ls foo + # ls: cannot access 'foo': No such file or directory + # echo foo > mk_contexts + # ls foo + # attrs init_regions kdamond_pid schemes target_ids + +If the context is not needed anymore, you can remove it and the corresponding +directory by putting the name of the context to the ``rm_contexts`` file. :: + + # echo foo > rm_contexts + # ls foo + # ls: cannot access 'foo': No such file or directory + +Note that ``mk_contexts``, ``rm_contexts``, and ``monitor_on`` files are in the +root directory only. + + .. _tracepoint: Tracepoint for Monitoring Results |