[PATCH v2 0/2] mm/damon: preserve temporal quota state for unmeasured PSI goals

[Karl Mehltretter <kmehltretter@gmail.com>]

A PSI quota goal without a previous sample is scored as achieved. This
leaves the consist tuner's input unchanged but sets the temporal quota
to zero. Preserve the temporal tuner's previous goal-achievement state
using its effective quota, as SJ suggested [1], and test the helper with
explicit PSI totals.

All 42 DAMON KUnit tests pass on x86-64 and i386. With the original
scoring retained in the extracted helper, the new test fails on both.
In a live damo test, a goals-only update changes a running 64 KiB quota
to zero for an unmeasured round without the fix. With the fix, the
effective quota stays at 64 KiB. A full damo tune also needs the separate
quota-reset fix [3], so the context update preserves the running quota
used for this decision.

DAMON selftests show no new failures (QEMU TCG guest; the wss_estimation
test misses its accuracy bounds with and without the fix).

Changes since v1 [2]:
 - Use the previous effective quota for the temporal decision, including
   when it is zero. Keep resetting last_psi_total for new and updated
   goals.
 - Move the current-value calculation and last_psi_total update into a
   helper. Test both tuners with explicit samples and check
   last_psi_total after each call.

The series is based on mm-new as of September 20.

[1] https://lore.kernel.org/damon/20260916001311.101024-1-sj@kernel.org/
[2] https://lore.kernel.org/20260915060937.3423-1-kmehltretter@gmail.com/
[3] https://lore.kernel.org/20260921003047.12041-1-kmehltretter@gmail.com/

Karl Mehltretter (2):
  mm/damon/core: keep the temporal tuner quota over an unmeasured PSI
    round
  mm/damon/tests/core-kunit: test PSI goal values with explicit samples

 mm/damon/core.c             | 30 ++++++++++++++++++++------
 mm/damon/tests/core-kunit.h | 43 +++++++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+), 7 deletions(-)


base-commit: 185111f116aabf202d12ce440c0f6e9bae073514
-- 
2.53.0