selftests/damon/_damon_sysfs: support kdamond refresh_ms

Patch series "selftests/damon: test kdamond refresh_ms", v2.

The kdamond 'refresh_ms' sysfs file makes DAMON periodically update its
read-only sysfs files (DAMOS stats, tuned monitoring intervals and the
kdamond pid) on its own, so users don't have to write update keywords such
as 'update_schemes_stats' to the 'state' file.  It has no selftest
coverage.

The first patch adds refresh_ms support to the _damon_sysfs.py test
control module.  The second adds a test that sets refresh_ms and confirms
a scheme's stats are updated under sysfs without an explicit update
request; the test skips on kernels that predate the refresh_ms file.

Tested on current mainline under a DAMON-enabled kernel: the new test
passes and the existing DAMON selftests show no new failures.


This patch (of 2):

The Kdamond class has no way to set the kdamond-level 'refresh_ms' sysfs
file, which makes DAMON periodically update the read-only sysfs files
(DAMOS stats, tuned monitoring intervals and the kdamond pid) on its own.

Add a 'refresh_ms' parameter to Kdamond.  When it is set (including to
zero, to disable the periodic update), write it before turning the kdamond
on, so tests can exercise the auto-update behavior.  Leaving it unset
keeps the previous behavior of not touching the file, so callers running
against kernels without the feature are unaffected.

Link: https://lore.kernel.org/20260602131217.2210912-2-linuxoid@gmail.com
Link: https://lore.kernel.org/20260629144927.134237-2-sj@kernel.org
Signed-off-by: Ruslan Valiyev <linuxoid@gmail.com>
Reviewed-by: SJ Park <sj@kernel.org>
Signed-off-by: SJ Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions