From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Tue, 10 Dec 2024 20:10:04 +0000 (-0500)
Subject: slub: More optimistic sheaf return
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d39c28aafe4457dd892598afc737622409526aca;p=users%2Fjedix%2Flinux-maple.git

slub: More optimistic sheaf return

vbabka notes: this may not be universal win, needs evaluation

Namely it can return half-filled sheaf to the barn's full list.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---

diff --git a/mm/slub.c b/mm/slub.c
index a03cf92718d1..acff36201439 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5021,11 +5021,18 @@ void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp,
 			     struct slab_sheaf *sheaf)
 {
 	struct slub_percpu_sheaves *pcs;
-	bool refill = false;
+	bool keep = false;
 	struct node_barn *barn;
 
 	//TODO: handle oversize sheaf
 
+	/* Assume it will be kept */
+	if (!sheaf->size && refill_sheaf(s, sheaf, gfp)) {
+		sheaf_flush(s, sheaf);
+		free_empty_sheaf(s, sheaf);
+		return;
+	}
+
 	pcs = cpu_sheaves_lock(s->cpu_sheaves);
 
 	if (!pcs->spare) {
@@ -5034,7 +5041,7 @@ void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp,
 	} else if (pcs->barn->nr_full >= MAX_FULL_SHEAVES) {
 		/* racy check */
 		barn = pcs->barn;
-		refill = true;
+		keep = true;
 	}
 
 	cpu_sheaves_unlock(s->cpu_sheaves);
@@ -5042,11 +5049,8 @@ void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp,
 	if (!sheaf)
 		return;
 
-	/*
-	 * if the barn is full of full sheaves or we fail to refill the sheaf,
-	 * simply flush and free it
-	 */
-	if (!refill || refill_sheaf(s, sheaf, gfp)) {
+	/* if the barn is full, simply flush and free it */
+	if (!keep) {
 		sheaf_flush(s, sheaf);
 		free_empty_sheaf(s, sheaf);
 		return;