slab: Common Kmalloc cache determination
Extract the optimized lookup functions from slub and put them into
slab_common.c. Then make slab use these functions as well.
Joonsoo notes that this fixes some issues with constant folding which
also reduces the code size for slub.
https://lkml.org/lkml/2012/10/20/82
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
diff --git a/mm/slub.c b/mm/slub.c
index e813c2d..6184b08 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2982,7 +2982,7 @@
s->allocflags |= __GFP_COMP;
if (s->flags & SLAB_CACHE_DMA)
- s->allocflags |= SLUB_DMA;
+ s->allocflags |= GFP_DMA;
if (s->flags & SLAB_RECLAIM_ACCOUNT)
s->allocflags |= __GFP_RECLAIMABLE;
@@ -3210,64 +3210,6 @@
__setup("slub_nomerge", setup_slub_nomerge);
-/*
- * Conversion table for small slabs sizes / 8 to the index in the
- * kmalloc array. This is necessary for slabs < 192 since we have non power
- * of two cache sizes there. The size of larger slabs can be determined using
- * fls.
- */
-static s8 size_index[24] = {
- 3, /* 8 */
- 4, /* 16 */
- 5, /* 24 */
- 5, /* 32 */
- 6, /* 40 */
- 6, /* 48 */
- 6, /* 56 */
- 6, /* 64 */
- 1, /* 72 */
- 1, /* 80 */
- 1, /* 88 */
- 1, /* 96 */
- 7, /* 104 */
- 7, /* 112 */
- 7, /* 120 */
- 7, /* 128 */
- 2, /* 136 */
- 2, /* 144 */
- 2, /* 152 */
- 2, /* 160 */
- 2, /* 168 */
- 2, /* 176 */
- 2, /* 184 */
- 2 /* 192 */
-};
-
-static inline int size_index_elem(size_t bytes)
-{
- return (bytes - 1) / 8;
-}
-
-static struct kmem_cache *get_slab(size_t size, gfp_t flags)
-{
- int index;
-
- if (size <= 192) {
- if (!size)
- return ZERO_SIZE_PTR;
-
- index = size_index[size_index_elem(size)];
- } else
- index = fls(size - 1);
-
-#ifdef CONFIG_ZONE_DMA
- if (unlikely((flags & SLUB_DMA)))
- return kmalloc_dma_caches[index];
-
-#endif
- return kmalloc_caches[index];
-}
-
void *__kmalloc(size_t size, gfp_t flags)
{
struct kmem_cache *s;
@@ -3276,7 +3218,7 @@
if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
return kmalloc_large(size, flags);
- s = get_slab(size, flags);
+ s = kmalloc_slab(size, flags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;
@@ -3319,7 +3261,7 @@
return ret;
}
- s = get_slab(size, flags);
+ s = kmalloc_slab(size, flags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;
@@ -3632,7 +3574,6 @@
{
static __initdata struct kmem_cache boot_kmem_cache,
boot_kmem_cache_node;
- int i;
if (debug_guardpage_minorder())
slub_max_order = 0;
@@ -3663,45 +3604,6 @@
kmem_cache_node = bootstrap(&boot_kmem_cache_node);
/* Now we can use the kmem_cache to allocate kmalloc slabs */
-
- /*
- * Patch up the size_index table if we have strange large alignment
- * requirements for the kmalloc array. This is only the case for
- * MIPS it seems. The standard arches will not generate any code here.
- *
- * Largest permitted alignment is 256 bytes due to the way we
- * handle the index determination for the smaller caches.
- *
- * Make sure that nothing crazy happens if someone starts tinkering
- * around with ARCH_KMALLOC_MINALIGN
- */
- BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
- (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
-
- for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
- int elem = size_index_elem(i);
- if (elem >= ARRAY_SIZE(size_index))
- break;
- size_index[elem] = KMALLOC_SHIFT_LOW;
- }
-
- if (KMALLOC_MIN_SIZE == 64) {
- /*
- * The 96 byte size cache is not used if the alignment
- * is 64 byte.
- */
- for (i = 64 + 8; i <= 96; i += 8)
- size_index[size_index_elem(i)] = 7;
- } else if (KMALLOC_MIN_SIZE == 128) {
- /*
- * The 192 byte sized cache is not used if the alignment
- * is 128 byte. Redirect kmalloc to use the 256 byte cache
- * instead.
- */
- for (i = 128 + 8; i <= 192; i += 8)
- size_index[size_index_elem(i)] = 8;
- }
-
create_kmalloc_caches(0);
#ifdef CONFIG_SMP
@@ -3877,7 +3779,7 @@
if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
return kmalloc_large(size, gfpflags);
- s = get_slab(size, gfpflags);
+ s = kmalloc_slab(size, gfpflags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;
@@ -3907,7 +3809,7 @@
return ret;
}
- s = get_slab(size, gfpflags);
+ s = kmalloc_slab(size, gfpflags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;