linux-kernel - [PATCH 3/4] mm/slub: simplify get_partial

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Date: Sun, 31 Mar 2024 10:19:25 +0800
From: <xiongwei.song@...driver.com>
To: <vbabka@...e.cz>, <rientjes@...gle.com>, <cl@...ux.com>,
        <penberg@...nel.org>, <iamjoonsoo.kim@....com>,
        <akpm@...ux-foundation.org>, <roman.gushchin@...ux.dev>,
        <42.hyeyoo@...il.com>
CC: <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <chengming.zhou@...ux.dev>
Subject: [PATCH 3/4] mm/slub: simplify get_partial_node()

From: Xiongwei Song <xiongwei.song@...driver.com>

The break conditions can be more readable and simple.

We can check if we need to fill cpu partial after getting the first
partial slab. If kmem_cache_has_cpu_partial() returns true, we fill
cpu partial from next iteration, or break up the loop.

Then we can remove the preprocessor condition of
CONFIG_SLUB_CPU_PARTIAL. Use dummy slub_get_cpu_partial() to make
compiler silent.

Signed-off-by: Xiongwei Song <xiongwei.song@...driver.com>
---
 mm/slub.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 590cc953895d..ec91c7435d4e 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2614,18 +2614,20 @@ static struct slab *get_partial_node(struct kmem_cache *s,
 		if (!partial) {
 			partial = slab;
 			stat(s, ALLOC_FROM_PARTIAL);
-		} else {
-			put_cpu_partial(s, slab, 0);
-			stat(s, CPU_PARTIAL_NODE);
-			partial_slabs++;
+
+			/* Fill cpu partial if needed from next iteration, or break */
+			if (kmem_cache_has_cpu_partial(s))
+				continue;
+			else
+				break;
 		}
-#ifdef CONFIG_SLUB_CPU_PARTIAL
-		if (partial_slabs > s->cpu_partial_slabs / 2)
-			break;
-#else
-		break;
-#endif
 
+		put_cpu_partial(s, slab, 0);
+		stat(s, CPU_PARTIAL_NODE);
+		partial_slabs++;
+
+		if (partial_slabs > slub_get_cpu_partial(s) / 2)
+			break;
 	}
 	spin_unlock_irqrestore(&n->list_lock, flags);
 	return partial;
-- 
2.27.0