2024-04-19 17:56:56

by Jianfeng Wang

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 <[email protected]>
---
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

2024-04-20 00:18:54

by David Rientjes

Subject: Re: [PATCH v3 2/2] slub: use count_partial_free_approx() in slab_out_of_memory()

On Fri, 19 Apr 2024, Jianfeng Wang wrote:

> 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 <[email protected]>

Acked-by: David Rientjes <[email protected]>