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Message-Id: <20231031140741.79387-4-chengming.zhou@linux.dev>
Date: Tue, 31 Oct 2023 14:07:35 +0000
From: chengming.zhou@...ux.dev
To: vbabka@...e.cz, cl@...ux.com, penberg@...nel.org,
willy@...radead.org
Cc: rientjes@...gle.com, iamjoonsoo.kim@....com,
akpm@...ux-foundation.org, roman.gushchin@...ux.dev,
42.hyeyoo@...il.com, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, chengming.zhou@...ux.dev,
Chengming Zhou <zhouchengming@...edance.com>
Subject: [RFC PATCH v4 3/9] slub: Keep track of whether slub is on the per-node partial list
From: Chengming Zhou <zhouchengming@...edance.com>
Now we rely on the "frozen" bit to see if we should manipulate the
slab->slab_list, which will be changed in the following patch.
Instead we introduce another way to keep track of whether slub is on
the per-node partial list, here we reuse the PG_workingset bit.
We use __set_bit and __clear_bit directly instead of the atomic version
for better performance and it's safe since it's protected by the slub
node list_lock.
Suggested-by: Matthew Wilcox <willy@...radead.org>
Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
---
mm/slub.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/mm/slub.c b/mm/slub.c
index 03384cd965c5..eed8ae0dbaf9 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2116,6 +2116,25 @@ static void discard_slab(struct kmem_cache *s, struct slab *slab)
free_slab(s, slab);
}
+/*
+ * SLUB reuses PG_workingset bit to keep track of whether it's on
+ * the per-node partial list.
+ */
+static inline bool slab_test_node_partial(const struct slab *slab)
+{
+ return folio_test_workingset((struct folio *)slab_folio(slab));
+}
+
+static inline void slab_set_node_partial(struct slab *slab)
+{
+ __set_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
+}
+
+static inline void slab_clear_node_partial(struct slab *slab)
+{
+ __clear_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
+}
+
/*
* Management of partially allocated slabs.
*/
@@ -2127,6 +2146,7 @@ __add_partial(struct kmem_cache_node *n, struct slab *slab, int tail)
list_add_tail(&slab->slab_list, &n->partial);
else
list_add(&slab->slab_list, &n->partial);
+ slab_set_node_partial(slab);
}
static inline void add_partial(struct kmem_cache_node *n,
@@ -2141,6 +2161,7 @@ static inline void remove_partial(struct kmem_cache_node *n,
{
lockdep_assert_held(&n->list_lock);
list_del(&slab->slab_list);
+ slab_clear_node_partial(slab);
n->nr_partial--;
}
@@ -4833,6 +4854,7 @@ static int __kmem_cache_do_shrink(struct kmem_cache *s)
if (free == slab->objects) {
list_move(&slab->slab_list, &discard);
+ slab_clear_node_partial(slab);
n->nr_partial--;
dec_slabs_node(s, node, slab->objects);
} else if (free <= SHRINK_PROMOTE_MAX)
--
2.20.1
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