On 2020-05-25T11:15:06+02:00 SeongJae Park <sjpark@xxxxxxxxxx> wrote: > From: SeongJae Park <sjpark@xxxxxxxxx> > > This commit adds a debugfs interface for DAMON. > > DAMON exports four files, ``attrs``, ``pids``, ``record``, and > ``monitor_on`` under its debugfs directory, ``<debugfs>/damon/``. > > Attributes > ---------- > > Users can read and write the ``sampling interval``, ``aggregation > interval``, ``regions update interval``, and min/max number of > monitoring target regions by reading from and writing to the ``attrs`` > file. For example, below commands set those values to 5 ms, 100 ms, > 1,000 ms, 10, 1000 and check it again:: > > # cd <debugfs>/damon > # echo 5000 100000 1000000 10 1000 > attrs > # cat attrs > 5000 100000 1000000 10 1000 > > Target PIDs > ----------- > > Users can read and write the pids of current monitoring target processes > by reading from and writing to the ``pids`` file. For example, below > commands set processes having pids 42 and 4242 as the processes to be > monitored and check it again:: > > # cd <debugfs>/damon > # echo 42 4242 > pids > # cat pids > 42 4242 > > Note that setting the pids doesn't start the monitoring. > > Record > ------ > > DAMON supports direct monitoring result record feature. The recorded > results are first written to a buffer and flushed to a file in batch. > Users can set the size of the buffer and the path to the result file by > reading from and writing to the ``record`` file. For example, below > commands set the buffer to be 4 KiB and the result to be saved in > '/damon.data'. > > # cd <debugfs>/damon > # echo 4096 /damon.data > pids > # cat record > 4096 /damon.data > > Turning On/Off > -------------- > > You can check current status, start and stop the monitoring by reading > from and writing to the ``monitor_on`` file. Writing ``on`` to the file > starts DAMON to monitor the target processes with the attributes. > Writing ``off`` to the file stops DAMON. DAMON also stops if every > target processes is terminated. Below example commands turn on, off, > and check status of DAMON:: > > # cd <debugfs>/damon > # echo on > monitor_on > # echo off > monitor_on > # cat monitor_on > off > > Please note that you cannot write to the ``attrs`` and ``pids`` files > while the monitoring is turned on. If you write to the files while > DAMON is running, ``-EINVAL`` will be returned. > > Signed-off-by: SeongJae Park <sjpark@xxxxxxxxx> > --- Reviewed-by: Leonard Foerster <foersleo@xxxxxxxxx>
