linux-kernel - [RFC PATCH 0/2] mm/damon/stat: expose auto-tuned intervals and non-idle ages

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Message-Id: <20250910040022.168223-1-sj@kernel.org>
Date: Tue,  9 Sep 2025 21:00:20 -0700
From: SeongJae Park <sj@...nel.org>
To: 
Cc: SeongJae Park <sj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	damon@...ts.linux.dev,
	kernel-team@...a.com,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [RFC PATCH 0/2] mm/damon/stat: expose auto-tuned intervals and non-idle ages

DAMON_STAT is intentionally providing limited information for easy
consumption.  From production fleet level usages, below limitations are
found, though.

The aggregation interval of DAMON_STAT represents the granularity of the
memory_idle_ms_percentiles.  But it is auto-tuned and not exposed to
users, so users cannot know the granularity.

All memory regions of non-zero (positive) nr_accesses are treated as
having zero idle time.  A significant portion of production systems have
such zero idle time.  Hence breakdown of warm and hot data is
impossible.

To overcome the limitations, expose the auto-tuned aggregation interval
with a new parameter named xxx and the age of non-zero nr_accesses
regions as negative idle time, via the existing idle time percentiles
parameter.

SeongJae Park (2):
  mm/damon/stat: expose the current tuned aggregation interval
  mm/damon/stat: expose negative idle time

 mm/damon/stat.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

base-commit: adc22cc8eb821b7d8274403ad7bdafb411fcc9d7
-- 
2.39.5