mm/damon/sysfs-schemes: do not update tried regions more than one DAMON snapshot

mm/damon/sysfs-schemes: do not update tried regions more than one DAMON snapshot

Patch series "mm/damon/sysfs-schemes: Do DAMOS tried regions update for
only one apply interval".

DAMOS tried regions update feature of DAMON sysfs interface is doing the
update for one aggregation interval after the request is made.  Since the
per-scheme apply interval is supported, that behavior makes no much sense.
That is, the tried regions directory will have regions from multiple
DAMON monitoring results snapshots, or no region for apply intervals that
much shorter than, or longer than the aggregation interval, respectively.
Update the behavior to update the regions for each scheme for only its
apply interval, and update the document.

Since DAMOS apply interval is the aggregation by default, this change
makes no visible behavioral difference to old users who don't explicitly
set the apply intervals.

Patches Sequence
----------------

The first two patches makes schemes of apply intervals that much shorter
or longer than the aggregation interval to keep the maximum and minimum
times for continuing the update.  After the two patches, the update aligns
with the each scheme's apply interval.

Finally, the third patch updates the document to reflect the behavior.

This patch (of 3):

DAMON_SYSFS exposes every DAMON-found region that eligible for applying
the scheme action for one aggregation interval.  However, each DAMON-based
operation scheme has its own apply interval.  Hence, for a scheme that
having its apply interval much smaller than the aggregation interval,
DAMON_SYSFS will expose the scheme regions that applied to more than one
DAMON monitoring results snapshots.  Since the purpose of DAMON tried
regions is exposing single snapshot, this makes no much sense.  Track
progress of each scheme's tried regions update and avoid the case.

Link: https://lkml.kernel.org/r/20231012192256.33556-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20231012192256.33556-2-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>