linux-kernel - [PATCH RESEND] mm/vmscan: simplify shrink

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Date:   Tue, 11 Apr 2023 06:17:57 +0000
From:   Haifeng Xu <haifeng.xu@...pee.com>
To:     akpm@...ux-foundation.org
Cc:     david@...hat.com, willy@...radead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Haifeng Xu <haifeng.xu@...pee.com>
Subject: [PATCH RESEND] mm/vmscan: simplify shrink_node()

The difference between sc->nr_reclaimed and nr_reclaimed is computed
three times. Introduce a new variable to record the value, so it only
needs to be computed once.

Signed-off-by: Haifeng Xu <haifeng.xu@...pee.com>
---
 mm/vmscan.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9c1c5e8b24b8..b86573104974 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -6451,7 +6451,7 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
 static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 {
 	struct reclaim_state *reclaim_state = current->reclaim_state;
-	unsigned long nr_reclaimed, nr_scanned;
+	unsigned long nr_reclaimed, nr_scanned, nr_node_reclaimed;
 	struct lruvec *target_lruvec;
 	bool reclaimable = false;
 
@@ -6477,13 +6477,14 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 		reclaim_state->reclaimed_slab = 0;
 	}
 
+	nr_node_reclaimed = sc->nr_reclaimed - nr_reclaimed;
+
 	/* Record the subtree's reclaim efficiency */
 	if (!sc->proactive)
 		vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true,
-			   sc->nr_scanned - nr_scanned,
-			   sc->nr_reclaimed - nr_reclaimed);
+			   sc->nr_scanned - nr_scanned, nr_node_reclaimed);
 
-	if (sc->nr_reclaimed - nr_reclaimed)
+	if (nr_node_reclaimed)
 		reclaimable = true;
 
 	if (current_is_kswapd()) {
@@ -6545,8 +6546,7 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 	    test_bit(LRUVEC_CONGESTED, &target_lruvec->flags))
 		reclaim_throttle(pgdat, VMSCAN_THROTTLE_CONGESTED);
 
-	if (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed,
-				    sc))
+	if (should_continue_reclaim(pgdat, nr_node_reclaimed, sc))
 		goto again;
 
 	/*
-- 
2.25.1