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From:   xiakaixu1987@gmail.com
To:     sj@kernel.org, akpm@linux-foundation.org
Cc:     damon@lists.linux.dev, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Kaixu Xia <kaixuxia@tencent.com>
Subject: [PATCH] mm/damon: get the hotness from damon_hot_score() in damon_pageout_score()
Date:   Mon, 29 Aug 2022 17:46:06 +0800
Message-Id: <1661766366-20998-1-git-send-email-kaixuxia@tencent.com>
Precedence: bulk

From: Kaixu Xia <kaixuxia@tencent.com>

We can get the hotness value from damon_hot_score() directly in
damon_pageout_score() function and improve the code readability.

Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
---
 mm/damon/ops-common.c | 46 ++++++-------------------------------------
 1 file changed, 6 insertions(+), 40 deletions(-)

diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c
index b1335de200e7..f599838b5f64 100644
--- a/mm/damon/ops-common.c
+++ b/mm/damon/ops-common.c
@@ -88,7 +88,7 @@ void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr)
 #define DAMON_MAX_SUBSCORE	(100)
 #define DAMON_MAX_AGE_IN_LOG	(32)
 
-int damon_pageout_score(struct damon_ctx *c, struct damon_region *r,
+int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
 			struct damos *s)
 {
 	unsigned int max_nr_accesses;
@@ -127,48 +127,14 @@ int damon_pageout_score(struct damon_ctx *c, struct damon_region *r,
 	 */
 	hotness = hotness * DAMOS_MAX_SCORE / DAMON_MAX_SUBSCORE;
 
-	/* Return coldness of the region */
-	return DAMOS_MAX_SCORE - hotness;
+	return hotness;
 }
 
-int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
+int damon_pageout_score(struct damon_ctx *c, struct damon_region *r,
 			struct damos *s)
 {
-	unsigned int max_nr_accesses;
-	int freq_subscore;
-	unsigned int age_in_sec;
-	int age_in_log, age_subscore;
-	unsigned int freq_weight = s->quota.weight_nr_accesses;
-	unsigned int age_weight = s->quota.weight_age;
-	int hotness;
-
-	max_nr_accesses = c->aggr_interval / c->sample_interval;
-	freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE / max_nr_accesses;
+	int hotness = damon_hot_score(c, r, s);
 
-	age_in_sec = (unsigned long)r->age * c->aggr_interval / 1000000;
-	for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec;
-			age_in_log++, age_in_sec >>= 1)
-		;
-
-	/* If frequency is 0, higher age means it's colder */
-	if (freq_subscore == 0)
-		age_in_log *= -1;
-
-	/*
-	 * Now age_in_log is in [-DAMON_MAX_AGE_IN_LOG, DAMON_MAX_AGE_IN_LOG].
-	 * Scale it to be in [0, 100] and set it as age subscore.
-	 */
-	age_in_log += DAMON_MAX_AGE_IN_LOG;
-	age_subscore = age_in_log * DAMON_MAX_SUBSCORE /
-		DAMON_MAX_AGE_IN_LOG / 2;
-
-	hotness = (freq_weight * freq_subscore + age_weight * age_subscore);
-	if (freq_weight + age_weight)
-		hotness /= freq_weight + age_weight;
-	/*
-	 * Transform it to fit in [0, DAMOS_MAX_SCORE]
-	 */
-	hotness = hotness * DAMOS_MAX_SCORE / DAMON_MAX_SUBSCORE;
-
-	return hotness;
+	/* Return coldness of the region */
+	return DAMOS_MAX_SCORE - hotness;
 }
-- 
2.27.0