patches/old/mm-damon-sysfs-implement-a-command-to-update-auto-tuned-monitoring-intervals.patch

From: SeongJae Park <sj@kernel.org>
Subject: mm/damon/sysfs: implement a command to update auto-tuned monitoring intervals
Date: Mon, 3 Mar 2025 14:17:23 -0800

DAMON kernel API callers can show auto-tuned sampling and aggregation
intervals from the monmitoring attributes data structure.  That can be
useful for debugging or tuning of the feature.  DAMON user-space ABI users
has no way to see that, though.  Implement a new DAMON sysfs interface
command, namely 'update_tuned_intervals', for the purpose.  If the command
is written to the kdamond state file, the tuned sampling and aggregation
intervals will be updated to the corresponding sysfs interface files.

Link: https://lkml.kernel.org/r/20250303221726.484227-6-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>
---

 mm/damon/sysfs.c |   20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

--- a/mm/damon/sysfs.c~mm-damon-sysfs-implement-a-command-to-update-auto-tuned-monitoring-intervals
+++ a/mm/damon/sysfs.c
@@ -1214,6 +1214,11 @@ enum damon_sysfs_cmd {
 	 */
 	DAMON_SYSFS_CMD_UPDATE_SCHEMES_EFFECTIVE_QUOTAS,
 	/*
+	 * @DAMON_SYSFS_CMD_UPDATE_TUNED_INTERVALS: Update the tuned monitoring
+	 * intevals.
+	 */
+	DAMON_SYSFS_CMD_UPDATE_TUNED_INTERVALS,
+	/*
 	 * @NR_DAMON_SYSFS_CMDS: Total number of DAMON sysfs commands.
 	 */
 	NR_DAMON_SYSFS_CMDS,
@@ -1230,6 +1235,7 @@ static const char * const damon_sysfs_cm
 	"update_schemes_tried_regions",
 	"clear_schemes_tried_regions",
 	"update_schemes_effective_quotas",
+	"update_tuned_intervals",
 };
 
 /*
@@ -1502,6 +1508,17 @@ static int damon_sysfs_upd_schemes_effec
 	return 0;
 }
 
+static int damon_sysfs_upd_tuned_intervals(void *data)
+{
+	struct damon_sysfs_kdamond *kdamond = data;
+	struct damon_ctx *ctx = kdamond->damon_ctx;
+
+	kdamond->contexts->contexts_arr[0]->attrs->intervals->sample_us =
+		ctx->attrs.sample_interval;
+	kdamond->contexts->contexts_arr[0]->attrs->intervals->aggr_us =
+		ctx->attrs.aggr_interval;
+	return 0;
+}
 
 /*
  * damon_sysfs_cmd_request_callback() - DAMON callback for handling requests.
@@ -1723,6 +1740,9 @@ static int damon_sysfs_handle_cmd(enum d
 		return damon_sysfs_damon_call(
 				damon_sysfs_upd_schemes_effective_quotas,
 				kdamond);
+	case DAMON_SYSFS_CMD_UPDATE_TUNED_INTERVALS:
+		return damon_sysfs_damon_call(
+				damon_sysfs_upd_tuned_intervals, kdamond);
 	default:
 		break;
 	}
_