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authorJoonsoo Kim <iamjoonsoo.kim@lge.com>2014-10-09 15:26:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-10-09 22:25:51 -0400
commit423c929cbbecc60e9c407f9048e58f5422f7995d (patch)
tree34f427883c02de08d9819db705c91ec418411643 /mm/slab_common.c
parent9163582c3f22cfba90a78749751ac70b127a9167 (diff)
mm/slab_common: commonize slab merge logic
Slab merge is good feature to reduce fragmentation. Now, it is only applied to SLUB, but, it would be good to apply it to SLAB. This patch is preparation step to apply slab merge to SLAB by commonizing slab merge logic. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab_common.c')
-rw-r--r--mm/slab_common.c91
1 files changed, 91 insertions, 0 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c
index d7d8ffd0c306..f206cb10a544 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -31,6 +31,34 @@ DEFINE_MUTEX(slab_mutex);
struct kmem_cache *kmem_cache;
/*
+ * Set of flags that will prevent slab merging
+ */
+#define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
+ SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
+ SLAB_FAILSLAB)
+
+#define SLAB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
+ SLAB_CACHE_DMA | SLAB_NOTRACK)
+
+/*
+ * Merge control. If this is set then no merging of slab caches will occur.
+ * (Could be removed. This was introduced to pacify the merge skeptics.)
+ */
+static int slab_nomerge;
+
+static int __init setup_slab_nomerge(char *str)
+{
+ slab_nomerge = 1;
+ return 1;
+}
+
+#ifdef CONFIG_SLUB
+__setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
+#endif
+
+__setup("slab_nomerge", setup_slab_nomerge);
+
+/*
* Determine the size of a slab object
*/
unsigned int kmem_cache_size(struct kmem_cache *s)
@@ -116,6 +144,69 @@ out:
#endif
/*
+ * Find a mergeable slab cache
+ */
+int slab_unmergeable(struct kmem_cache *s)
+{
+ if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
+ return 1;
+
+ if (!is_root_cache(s))
+ return 1;
+
+ if (s->ctor)
+ return 1;
+
+ /*
+ * We may have set a slab to be unmergeable during bootstrap.
+ */
+ if (s->refcount < 0)
+ return 1;
+
+ return 0;
+}
+
+struct kmem_cache *find_mergeable(size_t size, size_t align,
+ unsigned long flags, const char *name, void (*ctor)(void *))
+{
+ struct kmem_cache *s;
+
+ if (slab_nomerge || (flags & SLAB_NEVER_MERGE))
+ return NULL;
+
+ if (ctor)
+ return NULL;
+
+ size = ALIGN(size, sizeof(void *));
+ align = calculate_alignment(flags, align, size);
+ size = ALIGN(size, align);
+ flags = kmem_cache_flags(size, flags, name, NULL);
+
+ list_for_each_entry(s, &slab_caches, list) {
+ if (slab_unmergeable(s))
+ continue;
+
+ if (size > s->size)
+ continue;
+
+ if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
+ continue;
+ /*
+ * Check if alignment is compatible.
+ * Courtesy of Adrian Drzewiecki
+ */
+ if ((s->size & ~(align - 1)) != s->size)
+ continue;
+
+ if (s->size - size >= sizeof(void *))
+ continue;
+
+ return s;
+ }
+ return NULL;
+}
+
+/*
* Figure out what the alignment of the objects will be given a set of
* flags, a user specified alignment and the size of the objects.
*/