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

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Message-ID: <20260114055308.79884-1-sj@kernel.org>
Date: Tue, 13 Jan 2026 21:53:07 -0800
From: SeongJae Park <sj@...nel.org>
To: wang lian <lianux.mm@...il.com>
Cc: SeongJae Park <sj@...nel.org>,
	akpm@...ux-foundation.org,
	damon@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH 08/11] mm/damon/lru_sort: support active:inactive memory ratio based auto-tuning

On Wed, 14 Jan 2026 13:36:28 +0800 wang lian <lianux.mm@...il.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@...nel.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@...nel.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@...nel.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