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authorJesper Dangaard Brouer <brouer@redhat.com>2016-03-15 14:53:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-15 16:55:16 -0700
commit376bf125ac781d32e202760ed7deb1ae4ed35d31 (patch)
treebd794bfbf9a4a0d3a143db8382fd0356360449ae /mm/slub.c
parentdec63a4dec2d6d01346fd5d96062e67c0636852b (diff)
downloadlinux-376bf125ac781d32e202760ed7deb1ae4ed35d31.tar.bz2
slub: clean up code for kmem cgroup support to kmem_cache_free_bulk
This change is primarily an attempt to make it easier to realize the optimizations the compiler performs in-case CONFIG_MEMCG_KMEM is not enabled. Performance wise, even when CONFIG_MEMCG_KMEM is compiled in, the overhead is zero. This is because, as long as no process have enabled kmem cgroups accounting, the assignment is replaced by asm-NOP operations. This is possible because memcg_kmem_enabled() uses a static_key_false() construct. It also helps readability as it avoid accessing the p[] array like: p[size - 1] which "expose" that the array is processed backwards inside helper function build_detached_freelist(). Lastly this also makes the code more robust, in error case like passing NULL pointers in the array. Which were previously handled before commit 033745189b1b ("slub: add missing kmem cgroup support to kmem_cache_free_bulk"). Fixes: 033745189b1b ("slub: add missing kmem cgroup support to kmem_cache_free_bulk") Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slub.c')
-rw-r--r--mm/slub.c22
1 files changed, 11 insertions, 11 deletions
diff --git a/mm/slub.c b/mm/slub.c
index d8fbd4a6ed59..2a722e141958 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2815,6 +2815,7 @@ struct detached_freelist {
void *tail;
void *freelist;
int cnt;
+ struct kmem_cache *s;
};
/*
@@ -2829,8 +2830,9 @@ struct detached_freelist {
* synchronization primitive. Look ahead in the array is limited due
* to performance reasons.
*/
-static int build_detached_freelist(struct kmem_cache *s, size_t size,
- void **p, struct detached_freelist *df)
+static inline
+int build_detached_freelist(struct kmem_cache *s, size_t size,
+ void **p, struct detached_freelist *df)
{
size_t first_skipped_index = 0;
int lookahead = 3;
@@ -2846,8 +2848,11 @@ static int build_detached_freelist(struct kmem_cache *s, size_t size,
if (!object)
return 0;
+ /* Support for memcg, compiler can optimize this out */
+ df->s = cache_from_obj(s, object);
+
/* Start new detached freelist */
- set_freepointer(s, object, NULL);
+ set_freepointer(df->s, object, NULL);
df->page = virt_to_head_page(object);
df->tail = object;
df->freelist = object;
@@ -2862,7 +2867,7 @@ static int build_detached_freelist(struct kmem_cache *s, size_t size,
/* df->page is always set at this point */
if (df->page == virt_to_head_page(object)) {
/* Opportunity build freelist */
- set_freepointer(s, object, df->freelist);
+ set_freepointer(df->s, object, df->freelist);
df->freelist = object;
df->cnt++;
p[size] = NULL; /* mark object processed */
@@ -2881,25 +2886,20 @@ static int build_detached_freelist(struct kmem_cache *s, size_t size,
return first_skipped_index;
}
-
/* Note that interrupts must be enabled when calling this function. */
-void kmem_cache_free_bulk(struct kmem_cache *orig_s, size_t size, void **p)
+void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
{
if (WARN_ON(!size))
return;
do {
struct detached_freelist df;
- struct kmem_cache *s;
-
- /* Support for memcg */
- s = cache_from_obj(orig_s, p[size - 1]);
size = build_detached_freelist(s, size, p, &df);
if (unlikely(!df.page))
continue;
- slab_free(s, df.page, df.freelist, df.tail, df.cnt, _RET_IP_);
+ slab_free(df.s, df.page, df.freelist, df.tail, df.cnt,_RET_IP_);
} while (likely(size));
}
EXPORT_SYMBOL(kmem_cache_free_bulk);