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/include/linux/slub_def.h b/include/linux/slub_def.h
index 3701896..16341e5 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -115,29 +115,6 @@
struct kmem_cache_node *node[MAX_NUMNODES];
};
-#ifdef CONFIG_ZONE_DMA
-#define SLUB_DMA __GFP_DMA
-#else
-/* Disable DMA functionality */
-#define SLUB_DMA (__force gfp_t)0
-#endif
-
-/*
- * Find the slab cache for a given combination of allocation flags and size.
- *
- * This ought to end up with a global pointer to the right cache
- * in kmalloc_caches.
- */
-static __always_inline struct kmem_cache *kmalloc_slab(size_t size)
-{
- int index = kmalloc_index(size);
-
- if (index == 0)
- return NULL;
-
- return kmalloc_caches[index];
-}
-
void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
void *__kmalloc(size_t size, gfp_t flags);
@@ -195,13 +172,14 @@
if (size > KMALLOC_MAX_CACHE_SIZE)
return kmalloc_large(size, flags);
- if (!(flags & SLUB_DMA)) {
- struct kmem_cache *s = kmalloc_slab(size);
+ if (!(flags & GFP_DMA)) {
+ int index = kmalloc_index(size);
- if (!s)
+ if (!index)
return ZERO_SIZE_PTR;
- return kmem_cache_alloc_trace(s, flags, size);
+ return kmem_cache_alloc_trace(kmalloc_caches[index],
+ flags, size);
}
}
return __kmalloc(size, flags);
@@ -228,13 +206,14 @@
static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
{
if (__builtin_constant_p(size) &&
- size <= KMALLOC_MAX_CACHE_SIZE && !(flags & SLUB_DMA)) {
- struct kmem_cache *s = kmalloc_slab(size);
+ size <= KMALLOC_MAX_CACHE_SIZE && !(flags & GFP_DMA)) {
+ int index = kmalloc_index(size);
- if (!s)
+ if (!index)
return ZERO_SIZE_PTR;
- return kmem_cache_alloc_node_trace(s, flags, node, size);
+ return kmem_cache_alloc_node_trace(kmalloc_caches[index],
+ flags, node, size);
}
return __kmalloc_node(size, flags, node);
}
diff --git a/mm/slab.c b/mm/slab.c
index 08ba44f..62629b1 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -656,40 +656,6 @@
return cachep->array[smp_processor_id()];
}
-static inline struct kmem_cache *__find_general_cachep(size_t size,
- gfp_t gfpflags)
-{
- int i;
-
-#if DEBUG
- /* This happens if someone tries to call
- * kmem_cache_create(), or __kmalloc(), before
- * the generic caches are initialized.
- */
- BUG_ON(kmalloc_caches[INDEX_AC] == NULL);
-#endif
- if (!size)
- return ZERO_SIZE_PTR;
-
- i = kmalloc_index(size);
-
- /*
- * Really subtle: The last entry with cs->cs_size==ULONG_MAX
- * has cs_{dma,}cachep==NULL. Thus no special case
- * for large kmalloc calls required.
- */
-#ifdef CONFIG_ZONE_DMA
- if (unlikely(gfpflags & GFP_DMA))
- return kmalloc_dma_caches[i];
-#endif
- return kmalloc_caches[i];
-}
-
-static struct kmem_cache *kmem_find_general_cachep(size_t size, gfp_t gfpflags)
-{
- return __find_general_cachep(size, gfpflags);
-}
-
static size_t slab_mgmt_size(size_t nr_objs, size_t align)
{
return ALIGN(sizeof(struct slab)+nr_objs*sizeof(kmem_bufctl_t), align);
@@ -2426,7 +2392,7 @@
cachep->reciprocal_buffer_size = reciprocal_value(size);
if (flags & CFLGS_OFF_SLAB) {
- cachep->slabp_cache = kmem_find_general_cachep(slab_size, 0u);
+ cachep->slabp_cache = kmalloc_slab(slab_size, 0u);
/*
* This is a possibility for one of the malloc_sizes caches.
* But since we go off slab only for object size greater than
@@ -3729,7 +3695,7 @@
{
struct kmem_cache *cachep;
- cachep = kmem_find_general_cachep(size, flags);
+ cachep = kmalloc_slab(size, flags);
if (unlikely(ZERO_OR_NULL_PTR(cachep)))
return cachep;
return kmem_cache_alloc_node_trace(cachep, flags, node, size);
@@ -3774,7 +3740,7 @@
* Then kmalloc uses the uninlined functions instead of the inline
* functions.
*/
- cachep = __find_general_cachep(size, flags);
+ cachep = kmalloc_slab(size, flags);
if (unlikely(ZERO_OR_NULL_PTR(cachep)))
return cachep;
ret = slab_alloc(cachep, flags, caller);
diff --git a/mm/slab.h b/mm/slab.h
index 44c0bd6..c01bc89 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -38,6 +38,9 @@
#ifndef CONFIG_SLOB
/* Kmalloc array related functions */
void create_kmalloc_caches(unsigned long);
+
+/* Find the kmalloc slab corresponding for a certain size */
+struct kmem_cache *kmalloc_slab(size_t, gfp_t);
#endif
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 2b0ebb6..6d73f0b 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -328,6 +328,68 @@
#endif
/*
+ * 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;
+}
+
+/*
+ * Find the kmem_cache structure that serves a given size of
+ * allocation
+ */
+struct kmem_cache *kmalloc_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 & SLAB_CACHE_DMA)))
+ return kmalloc_dma_caches[index];
+
+#endif
+ return kmalloc_caches[index];
+}
+
+/*
* Create the kmalloc array. Some of the regular kmalloc arrays
* may already have been created because they were needed to
* enable allocations for slab creation.
@@ -336,6 +398,47 @@
{
int i;
+ /*
+ * 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;
+
+ }
+
+ 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;
+ }
/* Caches that are not of the two-to-the-power-of size */
if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1])
kmalloc_caches[1] = create_kmalloc_cache(NULL, 96, flags);
@@ -379,8 +482,6 @@
}
#endif
}
-
-
#endif /* !CONFIG_SLOB */
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;