1. Patchew
  2. linux
  3. [PATCH 00/11] mm/damon: advance DAMOS-based LRU sorting
  4. View patch

[PATCH 08/11] mm/damon/lru_sort: support active:inactive memory ratio based auto-tuning

SeongJae Park posted 11 patches 3 weeks, 3 days ago
[PATCH 08/11] mm/damon/lru_sort: support active:inactive memory ratio based auto-tuning
Posted by SeongJae Park 3 weeks, 3 days ago 
Doing DAMOS_LRU_[DE]PRIO with DAMOS_QUOTA_[IN]ACTIVE_MEM_BP based quota
auto-tuning can be easy and intuitive, compared to the manual
[de]prioritization target access pattern thresholds tuning.  For
example, users can ask DAMON to "find hot/cold pages and
activate/deactivate those aiming 50:50 active:inactive memory size." But
DAMON_LRU_SORT has no interface to do that.  Add a module parameter for
setting the target ratio.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/lru_sort.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index f1fdb37b9b47..f3a9dfc246b6 100644
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -41,6 +41,20 @@ static bool enabled __read_mostly;
 static bool commit_inputs __read_mostly;
 module_param(commit_inputs, bool, 0600);
 
+/*
+ * Desired active to [in]active memory ratio in bp (1/10,000).
+ *
+ * While keeping the caps that set by other quotas, DAMON_LRU_SORT
+ * automatically increases and decreases the effective level of the quota
+ * aiming the LRU [de]prioritizations of the hot and cold memory resulting in
+ * this active to [in]active memory ratio.  Value zero means disabling this
+ * auto-tuning feature.
+ *
+ * Disabled by default.
+ */
+static unsigned long active_mem_bp __read_mostly;
+module_param(active_mem_bp, ulong, 0600);
+
 /*
  * Filter [non-]young pages accordingly for LRU [de]prioritizations.
  *
@@ -208,6 +222,26 @@ static struct damos *damon_lru_sort_new_cold_scheme(unsigned int cold_thres)
 	return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_DEPRIO);
 }
 
+static int damon_lru_sort_add_quota_goals(struct damos *hot_scheme,
+		struct damos *cold_scheme)
+{
+	struct damos_quota_goal *goal;
+
+	if (!active_mem_bp)
+		return 0;
+	goal = damos_new_quota_goal(DAMOS_QUOTA_ACTIVE_MEM_BP, active_mem_bp);
+	if (!goal)
+		return -ENOMEM;
+	damos_add_quota_goal(&hot_scheme->quota, goal);
+	/* aim 0.2 % goal conflict, to keep little ping pong */
+	goal = damos_new_quota_goal(DAMOS_QUOTA_INACTIVE_MEM_BP,
+			10000 - active_mem_bp + 2);
+	if (!goal)
+		return -ENOMEM;
+	damos_add_quota_goal(&hot_scheme->quota, goal);
+	return 0;
+}
+
 static int damon_lru_sort_add_filters(struct damos *hot_scheme,
 		struct damos *cold_scheme)
 {
@@ -277,6 +311,9 @@ static int damon_lru_sort_apply_parameters(void)
 	damon_set_schemes(param_ctx, &hot_scheme, 1);
 	damon_add_scheme(param_ctx, cold_scheme);
 
+	err = damon_lru_sort_add_quota_goals(hot_scheme, cold_scheme);
+	if (err)
+		goto out;
 	err = damon_lru_sort_add_filters(hot_scheme, cold_scheme);
 	if (err)
 		goto out;
-- 
2.47.3
Re: [PATCH 08/11] mm/damon/lru_sort: support active:inactive memory ratio based auto-tuning
Posted by wang lian 3 weeks, 3 days ago 
> Doing DAMOS_LRU_[DE]PRIO with DAMOS_QUOTA_[IN]ACTIVE_MEM_BP based quota
> auto-tuning can be easy and intuitive, compared to the manual
> [de]prioritization target access pattern thresholds tuning.  For
> example, users can ask DAMON to "find hot/cold pages and
> activate/deactivate those aiming 50:50 active:inactive memory size." But
> DAMON_LRU_SORT has no interface to do that.  Add a module parameter for
> setting the target ratio.

> Signed-off-by: SeongJae Park <sj@kernel.org>

```
> +static int damon_lru_sort_add_quota_goals(struct damos *hot_scheme,
> +		struct damos *cold_scheme)
> +{
> 	struct damos_quota_goal *goal;
> +
> +	if (!active_mem_bp)
> +		return 0;
> +	goal = damos_new_quota_goal(DAMOS_QUOTA_ACTIVE_MEM_BP, active_mem_bp);
> +	if (!goal)
> +		return -ENOMEM;
> +	damos_add_quota_goal(&hot_scheme->quota, goal);
> +	/* aim 0.2 % goal conflict, to keep little ping pong */
> +	goal = damos_new_quota_goal(DAMOS_QUOTA_INACTIVE_MEM_BP,
> +			10000 - active_mem_bp + 2);
> +	if (!goal)
> +		return -ENOMEM;
> +	damos_add_quota_goal(&hot_scheme->quota, goal);
> +	return 0;
> +}

The second goal (Inactive ratio target) is added to hot_scheme again. 
Should this be cold_scheme? Currently the cold_scheme parameter appears to be unused.

--
Best Regards,
wang lian
Re: [PATCH 08/11] mm/damon/lru_sort: support active:inactive memory ratio based auto-tuning
Posted by SeongJae Park 3 weeks, 3 days ago 
On Wed, 14 Jan 2026 13:36:28 +0800 wang lian <lianux.mm@gmail.com> wrote:

> 
> > Doing DAMOS_LRU_[DE]PRIO with DAMOS_QUOTA_[IN]ACTIVE_MEM_BP based quota
> > auto-tuning can be easy and intuitive, compared to the manual
> > [de]prioritization target access pattern thresholds tuning.  For
> > example, users can ask DAMON to "find hot/cold pages and
> > activate/deactivate those aiming 50:50 active:inactive memory size." But
> > DAMON_LRU_SORT has no interface to do that.  Add a module parameter for
> > setting the target ratio.
> 
> > Signed-off-by: SeongJae Park <sj@kernel.org>
> 
> ```
> > +static int damon_lru_sort_add_quota_goals(struct damos *hot_scheme,
> > +		struct damos *cold_scheme)
> > +{
> > 	struct damos_quota_goal *goal;
> > +
> > +	if (!active_mem_bp)
> > +		return 0;
> > +	goal = damos_new_quota_goal(DAMOS_QUOTA_ACTIVE_MEM_BP, active_mem_bp);
> > +	if (!goal)
> > +		return -ENOMEM;
> > +	damos_add_quota_goal(&hot_scheme->quota, goal);
> > +	/* aim 0.2 % goal conflict, to keep little ping pong */
> > +	goal = damos_new_quota_goal(DAMOS_QUOTA_INACTIVE_MEM_BP,
> > +			10000 - active_mem_bp + 2);
> > +	if (!goal)
> > +		return -ENOMEM;
> > +	damos_add_quota_goal(&hot_scheme->quota, goal);
> > +	return 0;
> > +}
> 
> The second goal (Inactive ratio target) is added to hot_scheme again. 
> Should this be cold_scheme? Currently the cold_scheme parameter appears to be unused.

You are right, thank you for catching this, Wang!

Andrew, could you please add below attaching fixup?


Thanks,
SJ

[...]
=== >8 ===
From c8dbbf0cfb01de606d47f455bccc2d7b2d6d07ef Mon Sep 17 00:00:00 2001
From: SeongJae Park <sj@kernel.org>
Date: Tue, 13 Jan 2026 21:48:53 -0800
Subject: [PATCH] mm/damon/lru_sort: add inactive mem ratio quota goal to
 cold_scheme

damon_lru_sort_add_quota_goals() is adding inactive memory ratio quota
goal, which is for cold pages scheme, to hot pages scheme.  Fix it.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/lru_sort.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index f3a9dfc246b6..8af97642912a 100644
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -238,7 +238,7 @@ static int damon_lru_sort_add_quota_goals(struct damos *hot_scheme,
 			10000 - active_mem_bp + 2);
 	if (!goal)
 		return -ENOMEM;
-	damos_add_quota_goal(&hot_scheme->quota, goal);
+	damos_add_quota_goal(&cold_scheme->quota, goal);
 	return 0;
 }
 
-- 
2.47.3

Patchew 2.1-devel-b67e4c2

© 2016 - 2026 Red Hat, Inc.