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From: SeongJae Park <sj@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: SeongJae Park <sj@kernel.org>,
	damon@lists.linux.dev,
	linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 01/20] mm/damon/core: Set damos_quota->esz as public field and document
Date: Mon, 19 Feb 2024 11:44:12 -0800
Message-Id: <20240219194431.159606-2-sj@kernel.org>
In-Reply-To: <20240219194431.159606-1-sj@kernel.org>
References: <20240219194431.159606-1-sj@kernel.org>
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DAMOS allow users to specify the quota as they want in multiple ways
including time quota, size quota, and feedback-based auto-tuning.  DAMOS
makes one effective quota out of the inputs and use it at the end.
Knowing the current effective quota helps understanding DAMOS' internal
mechanism and fine-tuning quotas.  DAMON kernel API users can get the
information from ->esz field of damos_quota struct, but the field is
marked as private purpose, and not kernel-doc documented.  Make it
public and document.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 include/linux/damon.h | 6 ++++--
 mm/damon/core.c       | 8 ++++----
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 5881e4ac30be..93ef45b87b9c 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -138,6 +138,7 @@ enum damos_action {
  *
  * @get_score:		Feedback function for self-tuning quota.
  * @get_score_arg:	Parameter for @get_score
+ * @esz:		Effective size quota in bytes.
  *
  * To avoid consuming too much CPU time or IO resources for applying the
  * &struct damos->action to large memory, DAMON allows users to set time and/or
@@ -167,6 +168,8 @@ enum damos_action {
  * tuning is getting the feedback screo value of 10,000.  If @ms and/or @sz are
  * set together, those work as a hard limit quota.  If neither @ms nor @sz are
  * set, the mechanism starts from the quota of one byte.
+ *
+ * The resulting effective size quota in bytes is set to @esz.
  */
 struct damos_quota {
 	unsigned long ms;
@@ -179,14 +182,13 @@ struct damos_quota {
 
 	unsigned long (*get_score)(void *arg);
 	void *get_score_arg;
+	unsigned long esz;
 
 /* private: */
 	/* For throughput estimation */
 	unsigned long total_charged_sz;
 	unsigned long total_charged_ns;
 
-	unsigned long esz;	/* Effective size quota in bytes */
-
 	/* For charging the quota */
 	unsigned long charged_sz;
 	unsigned long charged_from;
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 5b325749fc12..0656966a6fc4 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -299,12 +299,12 @@ void damos_destroy_filter(struct damos_filter *f)
 	damos_free_filter(f);
 }
 
-/* initialize private fields of damos_quota and return the pointer */
-static struct damos_quota *damos_quota_init_priv(struct damos_quota *quota)
+/* initialize fields of @quota that normally API users wouldn't set */
+static struct damos_quota *damos_quota_init(struct damos_quota *quota)
 {
+	quota->esz = 0;
 	quota->total_charged_sz = 0;
 	quota->total_charged_ns = 0;
-	quota->esz = 0;
 	quota->charged_sz = 0;
 	quota->charged_from = 0;
 	quota->charge_target_from = NULL;
@@ -336,7 +336,7 @@ struct damos *damon_new_scheme(struct damos_access_pattern *pattern,
 	scheme->stat = (struct damos_stat){};
 	INIT_LIST_HEAD(&scheme->list);
 
-	scheme->quota = *(damos_quota_init_priv(quota));
+	scheme->quota = *(damos_quota_init(quota));
 
 	scheme->wmarks = *wmarks;
 	scheme->wmarks.activated = true;
-- 
2.39.2