linux-kernel - [RFC PATCH 1/2] mm/damon/stat: expose the current tuned aggregation interval

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Message-Id: <20250910040022.168223-2-sj@kernel.org>
Date: Tue,  9 Sep 2025 21:00:21 -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 1/2] mm/damon/stat: expose the current tuned aggregation interval

DAMON_STAT calculates the idle time for a region as the region's age
multiplied by the aggregation interval.  That is, the aggregation
interval is the granularity of the idle time.  Since the aggregation
interval is auto-tuned and not exposed to users, however, users cannot
easily know in what granularity the stat is made.  Expose the tuned
aggregation interval in microseconds via a new parameter,
aggr_interval_us.

Signed-off-by: SeongJae Park <sj@...nel.org>
---
 mm/damon/stat.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/damon/stat.c b/mm/damon/stat.c
index 87bcd8866d4b..ff1c076185e6 100644
--- a/mm/damon/stat.c
+++ b/mm/damon/stat.c
@@ -39,6 +39,11 @@ module_param_array(memory_idle_ms_percentiles, ulong, NULL, 0400);
 MODULE_PARM_DESC(memory_idle_ms_percentiles,
 		"Memory idle time percentiles in milliseconds");
 
+static unsigned long aggr_interval_us;
+module_param(aggr_interval_us, ulong, 0400);
+MODULE_PARM_DESC(aggr_interval_us,
+		"Current tuned aggregation interval in microseconds");
+
 static struct damon_ctx *damon_stat_context;
 
 static void damon_stat_set_estimated_memory_bandwidth(struct damon_ctx *c)
@@ -133,6 +138,7 @@ static int damon_stat_damon_call_fn(void *data)
 		return 0;
 	last_refresh_jiffies = jiffies;
 
+	aggr_interval_us = c->attrs.aggr_interval;
 	damon_stat_set_estimated_memory_bandwidth(c);
 	damon_stat_set_idletime_percentiles(c);
 	return 0;
-- 
2.39.5