linux-kernel - [PATCH v3 2/2] slub: use count_partial_free_approx() in slab_out_of

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Message-ID: <20240419175611.47413-3-jianfeng.w.wang@oracle.com>
Date: Fri, 19 Apr 2024 10:56:11 -0700
From: Jianfeng Wang <jianfeng.w.wang@...cle.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: vbabka@...e.cz, cl@...ux.com, akpm@...ux-foundation.org,
        penberg@...nel.org, rientjes@...gle.com
Subject: [PATCH v3 2/2] slub: use count_partial_free_approx() in slab_out_of_memory()

slab_out_of_memory() uses count_partial() to get the exact count
of free objects for each node. As it may get called in the slab
allocation path, count_partial_free_approx() can be used to avoid
the risk and overhead of traversing a long partial slab list.

At the same time, show_slab_objects() still uses count_partial().
Thus, slub users can still have the option to access the exact
count of objects via sysfs if the overhead is acceptable to them.

Signed-off-by: Jianfeng Wang <jianfeng.w.wang@...cle.com>
---
 mm/slub.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c
index 993cbbdd2b6c..fa55699aa21a 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3292,7 +3292,7 @@ slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
 		unsigned long nr_objs;
 		unsigned long nr_free;

-		nr_free  = count_partial(n, count_free);
+		nr_free  = count_partial_free_approx(n);
 		nr_slabs = node_nr_slabs(n);
 		nr_objs  = node_nr_objs(n);

-- 
2.42.1