Received-SPF: pass (google.com: domain of linux-kernel+bounces-163110-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
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 1/4] mm/damon/paddr: avoid unnecessary page level access check for pageout DAMOS action
Date: Mon, 29 Apr 2024 15:44:48 -0700
Message-Id: <20240429224451.67081-2-sj@kernel.org>
In-Reply-To: <20240429224451.67081-1-sj@kernel.org>
References: <20240429224451.67081-1-sj@kernel.org>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

'pageout' DAMOS action implementation of 'paddr' asks reclaim_pages() to
do the page level access check.  User could ask DAMOS to do the page
level access check on its own using 'young page' type DAMOS filter.  In
the case, pageout DAMOS action unnecessarily asks reclaim_pages() to do
the check again.  Ask the page level access check only if the scheme is
not having the filter.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/paddr.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 5685ba485097..d5f2f7ddf863 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -244,6 +244,16 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s)
 {
 	unsigned long addr, applied;
 	LIST_HEAD(folio_list);
+	bool ignore_references = false;
+	struct damos_filter *filter;
+
+	/* respect user's page level reference check handling request */
+	damos_for_each_filter(filter, s) {
+		if (filter->type == DAMOS_FILTER_TYPE_YOUNG) {
+			ignore_references = true;
+			break;
+		}
+	}
 
 	for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) {
 		struct folio *folio = damon_get_folio(PHYS_PFN(addr));
@@ -265,7 +275,7 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s)
 put_folio:
 		folio_put(folio);
 	}
-	applied = reclaim_pages(&folio_list, false);
+	applied = reclaim_pages(&folio_list, ignore_references);
 	cond_resched();
 	return applied * PAGE_SIZE;
 }
-- 
2.39.2