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mm/sl[aou]b: Common alignment code

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Extract the code to do object alignment from the allocators.
Do the alignment calculations in slab_common so that the
__kmem_cache_create functions of the allocators do not have
to deal with alignment.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This commit is contained in:
Christoph Lameter 2012-11-28 16:23:16 +00:00 • committed by Pekka Enberg
commit 4590685546
5 changed files with 34 additions and 69 deletions
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20
mm/slab.c
View file

@ -2337,22 +2337,6 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
size &= ~(BYTES_PER_WORD - 1);
}
/* calculate the final buffer alignment: */
/* 1) arch recommendation: can be overridden for debug */
if (flags & SLAB_HWCACHE_ALIGN) {
/*
* Default alignment: as specified by the arch code. Except if
* an object is really small, then squeeze multiple objects into
* one cacheline.
*/
ralign = cache_line_size();
while (size <= ralign / 2)
ralign /= 2;
} else {
ralign = BYTES_PER_WORD;
}
/*
* Redzoning and user store require word alignment or possibly larger.
* Note this will be overridden by architecture or caller mandated
@ -2369,10 +2353,6 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
size &= ~(REDZONE_ALIGN - 1);
}
/* 2) arch mandated alignment */
if (ralign < ARCH_SLAB_MINALIGN) {
ralign = ARCH_SLAB_MINALIGN;
}
/* 3) caller mandated alignment */
if (ralign < cachep->align) {
ralign = cachep->align;

3
mm/slab.h
View file

@ -32,6 +32,9 @@ extern struct list_head slab_caches;
/* The slab cache that manages slab cache information */
extern struct kmem_cache *kmem_cache;
unsigned long calculate_alignment(unsigned long flags,
unsigned long align, unsigned long size);
/* Functions provided by the slab allocators */
extern int __kmem_cache_create(struct kmem_cache *, unsigned long flags);

32
mm/slab_common.c
View file

@ -72,6 +72,34 @@ static inline int kmem_cache_sanity_check(const char *name, size_t size)
}
#endif
/*
* 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.
*/
unsigned long calculate_alignment(unsigned long flags,
unsigned long align, unsigned long size)
{
/*
* If the user wants hardware cache aligned objects then follow that
* suggestion if the object is sufficiently large.
*
* The hardware cache alignment cannot override the specified
* alignment though. If that is greater then use it.
*/
if (flags & SLAB_HWCACHE_ALIGN) {
unsigned long ralign = cache_line_size();
while (size <= ralign / 2)
ralign /= 2;
align = max(align, ralign);
}
if (align < ARCH_SLAB_MINALIGN)
align = ARCH_SLAB_MINALIGN;
return ALIGN(align, sizeof(void *));
}
/*
* kmem_cache_create - Create a cache.
* @name: A string which is used in /proc/slabinfo to identify this cache.
@ -124,7 +152,7 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
if (s) {
s->object_size = s->size = size;
s->align = align;
s->align = calculate_alignment(flags, align, size);
s->ctor = ctor;
s->name = kstrdup(name, GFP_KERNEL);
if (!s->name) {
@ -211,7 +239,7 @@ void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t siz
s->name = name;
s->size = s->object_size = size;
s->align = ARCH_KMALLOC_MINALIGN;
s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
err = __kmem_cache_create(s, flags);
if (err)

10
mm/slob.c
View file

@ -123,7 +123,6 @@ static inline void clear_slob_page_free(struct page *sp)
#define SLOB_UNIT sizeof(slob_t)
#define SLOB_UNITS(size) (((size) + SLOB_UNIT - 1)/SLOB_UNIT)
#define SLOB_ALIGN L1_CACHE_BYTES
/*
* struct slob_rcu is inserted at the tail of allocated slob blocks, which
@ -527,20 +526,11 @@ EXPORT_SYMBOL(ksize);
int __kmem_cache_create(struct kmem_cache *c, unsigned long flags)
{
size_t align = c->size;
if (flags & SLAB_DESTROY_BY_RCU) {
/* leave room for rcu footer at the end of object */
c->size += sizeof(struct slob_rcu);
}
c->flags = flags;
/* ignore alignment unless it's forced */
c->align = (flags & SLAB_HWCACHE_ALIGN) ? SLOB_ALIGN : 0;
if (c->align < ARCH_SLAB_MINALIGN)
c->align = ARCH_SLAB_MINALIGN;
if (c->align < align)
c->align = align;
return 0;
}

38
mm/slub.c
View file

@ -2760,32 +2760,6 @@ static inline int calculate_order(int size, int reserved)
return -ENOSYS;
}
/*
* Figure out what the alignment of the objects will be.
*/
static unsigned long calculate_alignment(unsigned long flags,
unsigned long align, unsigned long size)
{
/*
* If the user wants hardware cache aligned objects then follow that
* suggestion if the object is sufficiently large.
*
* The hardware cache alignment cannot override the specified
* alignment though. If that is greater then use it.
*/
if (flags & SLAB_HWCACHE_ALIGN) {
unsigned long ralign = cache_line_size();
while (size <= ralign / 2)
ralign /= 2;
align = max(align, ralign);
}
if (align < ARCH_SLAB_MINALIGN)
align = ARCH_SLAB_MINALIGN;
return ALIGN(align, sizeof(void *));
}
static void
init_kmem_cache_node(struct kmem_cache_node *n)
{
@ -2919,7 +2893,6 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
{
unsigned long flags = s->flags;
unsigned long size = s->object_size;
unsigned long align = s->align;
int order;
/*
@ -2990,20 +2963,12 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
size += sizeof(void *);
#endif
/*
* Determine the alignment based on various parameters that the
* user specified and the dynamic determination of cache line size
* on bootup.
*/
align = calculate_alignment(flags, align, s->object_size);
s->align = align;
/*
* SLUB stores one object immediately after another beginning from
* offset 0. In order to align the objects we have to simply size
* each object to conform to the alignment.
*/
size = ALIGN(size, align);
size = ALIGN(size, s->align);
s->size = size;
if (forced_order >= 0)
order = forced_order;
@ -3032,7 +2997,6 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
s->max = s->oo;
return !!oo_objects(s->oo);
}
static int kmem_cache_open(struct kmem_cache *s, unsigned long flags)