The patch titled
Subject: mm/slub: use percpu partial free counter
has been added to the -mm tree. Its filename is
mm-slub-use-percpu-partial-free-counter.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-slub-use-percpu-partial-free-counter.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-slub-use-percpu-partial-free-counter.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Xunlei Pang <xlpang@xxxxxxxxxxxxxxxxx>
Subject: mm/slub: use percpu partial free counter
The only concern of introducing partial counter is that, partial_free_objs
may cause cache and atomic operation contention in case of same SLUB
concurrent __slab_free().
This patch changes it to be a percpu counter, also replace the counter
variables to avoid cacheline issues.
Link: https://lkml.kernel.org/r/1615303512-35058-5-git-send-email-xlpang@xxxxxxxxxxxxxxxxx
Signed-off-by: Xunlei Pang <xlpang@xxxxxxxxxxxxxxxxx>
Tested-by: James Wang <jnwang@xxxxxxxxxxxxxxxxx>
Reviewed-by: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Shu Ming <sming56@xxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slab.h | 6 ++++--
mm/slub.c | 30 +++++++++++++++++++++++-------
2 files changed, 27 insertions(+), 9 deletions(-)
--- a/mm/slab.h~mm-slub-use-percpu-partial-free-counter
+++ a/mm/slab.h
@@ -546,16 +546,18 @@ struct kmem_cache_node {
#ifdef CONFIG_SLUB
unsigned long nr_partial;
- struct list_head partial;
#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
- atomic_long_t partial_free_objs;
unsigned long partial_total_objs;
#endif
+ struct list_head partial;
#ifdef CONFIG_SLUB_DEBUG
atomic_long_t nr_slabs;
atomic_long_t total_objects;
struct list_head full;
#endif
+#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
+ unsigned long __percpu *partial_free_objs;
+#endif
#endif
};
--- a/mm/slub.c~mm-slub-use-percpu-partial-free-counter
+++ a/mm/slub.c
@@ -1894,7 +1894,7 @@ static void discard_slab(struct kmem_cac
static inline void
__update_partial_free(struct kmem_cache_node *n, long delta)
{
- atomic_long_add(delta, &n->partial_free_objs);
+ this_cpu_add(*n->partial_free_objs, delta);
}
static inline void
@@ -2548,11 +2548,16 @@ static unsigned long partial_counter(str
unsigned long ret = 0;
if (item == PARTIAL_FREE) {
- ret = atomic_long_read(&n->partial_free_objs);
+ ret = per_cpu_sum(*n->partial_free_objs);
+ if ((long)ret < 0)
+ ret = 0;
} else if (item == PARTIAL_TOTAL) {
ret = n->partial_total_objs;
} else if (item == PARTIAL_INUSE) {
- ret = n->partial_total_objs - atomic_long_read(&n->partial_free_objs);
+ ret = per_cpu_sum(*n->partial_free_objs);
+ if ((long)ret < 0)
+ ret = 0;
+ ret = n->partial_total_objs - ret;
if ((long)ret < 0)
ret = 0;
}
@@ -3552,14 +3557,16 @@ static inline int calculate_order(unsign
return -ENOSYS;
}
-static void
+static int
init_kmem_cache_node(struct kmem_cache_node *n)
{
n->nr_partial = 0;
spin_lock_init(&n->list_lock);
INIT_LIST_HEAD(&n->partial);
#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
- atomic_long_set(&n->partial_free_objs, 0);
+ n->partial_free_objs = alloc_percpu(unsigned long);
+ if (!n->partial_free_objs)
+ return -ENOMEM;
n->partial_total_objs = 0;
#endif
#ifdef CONFIG_SLUB_DEBUG
@@ -3567,6 +3574,8 @@ init_kmem_cache_node(struct kmem_cache_n
atomic_long_set(&n->total_objects, 0);
INIT_LIST_HEAD(&n->full);
#endif
+
+ return 0;
}
static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
@@ -3626,7 +3635,7 @@ static void early_kmem_cache_node_alloc(
page->inuse = 1;
page->frozen = 0;
kmem_cache_node->node[node] = n;
- init_kmem_cache_node(n);
+ BUG_ON(init_kmem_cache_node(n) < 0);
inc_slabs_node(kmem_cache_node, node, page->objects);
/*
@@ -3644,6 +3653,9 @@ static void free_kmem_cache_nodes(struct
for_each_kmem_cache_node(s, node, n) {
s->node[node] = NULL;
+#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
+ free_percpu(n->partial_free_objs);
+#endif
kmem_cache_free(kmem_cache_node, n);
}
}
@@ -3674,7 +3686,11 @@ static int init_kmem_cache_nodes(struct
return 0;
}
- init_kmem_cache_node(n);
+ if (init_kmem_cache_node(n) < 0) {
+ free_kmem_cache_nodes(s);
+ return 0;
+ }
+
s->node[node] = n;
}
return 1;
_
Patches currently in -mm which might be from xlpang@xxxxxxxxxxxxxxxxx are
mm-slub-introduce-two-counters-for-partial-objects.patch
mm-slub-get-rid-of-count_partial.patch
percpu-export-per_cpu_sum.patch
mm-slub-use-percpu-partial-free-counter.patch
