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Merge branch 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux 

Pull slab changes from Pekka Enberg:
 "The biggest change is byte-sized freelist indices which reduces slab
  freelist memory usage:

    https://lkml.org/lkml/2013/12/2/64"

* 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux:
  mm: slab/slub: use page->list consistently instead of page->lru
  mm/slab.c: cleanup outdated comments and unify variables naming
  slab: fix wrongly used macro
  slub: fix high order page allocation problem with __GFP_NOFAIL
  slab: Make allocations with GFP_ZERO slightly more efficient
  slab: make more slab management structure off the slab
  slab: introduce byte sized index for the freelist of a slab
  slab: restrict the number of objects in a slab
  slab: introduce helper functions to get/set free object
  slab: factor out calculate nr objects in cache_estimate
This commit is contained in:
Linus Torvalds 2014-04-13 13:28:13 -07:00
parent 321d03c867 34bf6ef94a
commit bf3a340738
5 changed files with 128 additions and 84 deletions
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3
include/linux/mm_types.h
View File

@ -124,6 +124,8 @@ struct page {
union {
struct list_head lru; /* Pageout list, eg. active_list
* protected by zone->lru_lock !
* Can be used as a generic list
* by the page owner.
*/
struct { /* slub per cpu partial pages */
struct page *next; /* Next partial slab */
@ -136,7 +138,6 @@ struct page {
#endif
};
struct list_head list; /* slobs list of pages */
struct slab *slab_page; /* slab fields */
struct rcu_head rcu_head; /* Used by SLAB
* when destroying via RCU

11
include/linux/slab.h
View File

@ -242,6 +242,17 @@ struct kmem_cache {
#define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW)
#endif
/*
* This restriction comes from byte sized index implementation.
* Page size is normally 2^12 bytes and, in this case, if we want to use
* byte sized index which can represent 2^8 entries, the size of the object
* should be equal or greater to 2^12 / 2^8 = 2^4 = 16.
* If minimum size of kmalloc is less than 16, we use it as minimum object
* size and give up to use byte sized index.
*/
#define SLAB_OBJ_MIN_SIZE (KMALLOC_MIN_SIZE < 16 ? \
(KMALLOC_MIN_SIZE) : 16)
#ifndef CONFIG_SLOB
extern struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
#ifdef CONFIG_ZONE_DMA

183
mm/slab.c
View File

@ -157,6 +157,17 @@
#define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN
#endif
#define FREELIST_BYTE_INDEX (((PAGE_SIZE >> BITS_PER_BYTE) \
<= SLAB_OBJ_MIN_SIZE) ? 1 : 0)
#if FREELIST_BYTE_INDEX
typedef unsigned char freelist_idx_t;
#else
typedef unsigned short freelist_idx_t;
#endif
#define SLAB_OBJ_MAX_NUM (1 << sizeof(freelist_idx_t) * BITS_PER_BYTE)
/*
* true if a page was allocated from pfmemalloc reserves for network-based
* swap
@ -277,8 +288,8 @@ static void kmem_cache_node_init(struct kmem_cache_node *parent)
* OTOH the cpuarrays can contain lots of objects,
* which could lock up otherwise freeable slabs.
*/
#define REAPTIMEOUT_CPUC (2*HZ)
#define REAPTIMEOUT_LIST3 (4*HZ)
#define REAPTIMEOUT_AC (2*HZ)
#define REAPTIMEOUT_NODE (4*HZ)
#if STATS
#define STATS_INC_ACTIVE(x) ((x)->num_active++)
@ -565,9 +576,31 @@ static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
return cachep->array[smp_processor_id()];
}
static size_t slab_mgmt_size(size_t nr_objs, size_t align)
static int calculate_nr_objs(size_t slab_size, size_t buffer_size,
size_t idx_size, size_t align)
{
return ALIGN(nr_objs * sizeof(unsigned int), align);
int nr_objs;
size_t freelist_size;
/*
* Ignore padding for the initial guess. The padding
* is at most @align-1 bytes, and @buffer_size is at
* least @align. In the worst case, this result will
* be one greater than the number of objects that fit
* into the memory allocation when taking the padding
* into account.
*/
nr_objs = slab_size / (buffer_size + idx_size);
/*
* This calculated number will be either the right
* amount, or one greater than what we want.
*/
freelist_size = slab_size - nr_objs * buffer_size;
if (freelist_size < ALIGN(nr_objs * idx_size, align))
nr_objs--;
return nr_objs;
}
/*
@ -600,25 +633,9 @@ static void cache_estimate(unsigned long gfporder, size_t buffer_size,
nr_objs = slab_size / buffer_size;
} else {
/*
* Ignore padding for the initial guess. The padding
* is at most @align-1 bytes, and @buffer_size is at
* least @align. In the worst case, this result will
* be one greater than the number of objects that fit
* into the memory allocation when taking the padding
* into account.
*/
nr_objs = (slab_size) / (buffer_size + sizeof(unsigned int));
/*
* This calculated number will be either the right
* amount, or one greater than what we want.
*/
if (slab_mgmt_size(nr_objs, align) + nr_objs*buffer_size
> slab_size)
nr_objs--;
mgmt_size = slab_mgmt_size(nr_objs, align);
nr_objs = calculate_nr_objs(slab_size, buffer_size,
sizeof(freelist_idx_t), align);
mgmt_size = ALIGN(nr_objs * sizeof(freelist_idx_t), align);
}
*num = nr_objs;
*left_over = slab_size - nr_objs*buffer_size - mgmt_size;
@ -1067,7 +1084,7 @@ static int init_cache_node_node(int node)
list_for_each_entry(cachep, &slab_caches, list) {
/*
* Set up the size64 kmemlist for cpu before we can
* Set up the kmem_cache_node for cpu before we can
* begin anything. Make sure some other cpu on this
* node has not already allocated this
*/
@ -1076,12 +1093,12 @@ static int init_cache_node_node(int node)
if (!n)
return -ENOMEM;
kmem_cache_node_init(n);
n->next_reap = jiffies + REAPTIMEOUT_LIST3 +
((unsigned long)cachep) % REAPTIMEOUT_LIST3;
n->next_reap = jiffies + REAPTIMEOUT_NODE +
((unsigned long)cachep) % REAPTIMEOUT_NODE;
/*
* The l3s don't come and go as CPUs come and
* go. slab_mutex is sufficient
* The kmem_cache_nodes don't come and go as CPUs
* come and go. slab_mutex is sufficient
* protection here.
*/
cachep->node[node] = n;
@ -1406,8 +1423,8 @@ static void __init set_up_node(struct kmem_cache *cachep, int index)
for_each_online_node(node) {
cachep->node[node] = &init_kmem_cache_node[index + node];
cachep->node[node]->next_reap = jiffies +
REAPTIMEOUT_LIST3 +
((unsigned long)cachep) % REAPTIMEOUT_LIST3;
REAPTIMEOUT_NODE +
((unsigned long)cachep) % REAPTIMEOUT_NODE;
}
}
@ -2010,6 +2027,10 @@ static size_t calculate_slab_order(struct kmem_cache *cachep,
if (!num)
continue;
/* Can't handle number of objects more than SLAB_OBJ_MAX_NUM */
if (num > SLAB_OBJ_MAX_NUM)
break;
if (flags & CFLGS_OFF_SLAB) {
/*
* Max number of objs-per-slab for caches which
@ -2017,7 +2038,7 @@ static size_t calculate_slab_order(struct kmem_cache *cachep,
* looping condition in cache_grow().
*/
offslab_limit = size;
offslab_limit /= sizeof(unsigned int);
offslab_limit /= sizeof(freelist_idx_t);
if (num > offslab_limit)
break;
@ -2103,8 +2124,8 @@ static int __init_refok setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
}
}
cachep->node[numa_mem_id()]->next_reap =
jiffies + REAPTIMEOUT_LIST3 +
((unsigned long)cachep) % REAPTIMEOUT_LIST3;
jiffies + REAPTIMEOUT_NODE +
((unsigned long)cachep) % REAPTIMEOUT_NODE;
cpu_cache_get(cachep)->avail = 0;
cpu_cache_get(cachep)->limit = BOOT_CPUCACHE_ENTRIES;
@ -2243,7 +2264,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
* it too early on. Always use on-slab management when
* SLAB_NOLEAKTRACE to avoid recursive calls into kmemleak)
*/
if ((size >= (PAGE_SIZE >> 3)) && !slab_early_init &&
if ((size >= (PAGE_SIZE >> 5)) && !slab_early_init &&
!(flags & SLAB_NOLEAKTRACE))
/*
* Size is large, assume best to place the slab management obj
@ -2252,6 +2273,12 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
flags |= CFLGS_OFF_SLAB;
size = ALIGN(size, cachep->align);
/*
* We should restrict the number of objects in a slab to implement
* byte sized index. Refer comment on SLAB_OBJ_MIN_SIZE definition.
*/
if (FREELIST_BYTE_INDEX && size < SLAB_OBJ_MIN_SIZE)
size = ALIGN(SLAB_OBJ_MIN_SIZE, cachep->align);
left_over = calculate_slab_order(cachep, size, cachep->align, flags);
@ -2259,7 +2286,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
return -E2BIG;
freelist_size =
ALIGN(cachep->num * sizeof(unsigned int), cachep->align);
ALIGN(cachep->num * sizeof(freelist_idx_t), cachep->align);
/*
* If the slab has been placed off-slab, and we have enough space then
@ -2272,7 +2299,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
if (flags & CFLGS_OFF_SLAB) {
/* really off slab. No need for manual alignment */
freelist_size = cachep->num * sizeof(unsigned int);
freelist_size = cachep->num * sizeof(freelist_idx_t);
#ifdef CONFIG_PAGE_POISONING
/* If we're going to use the generic kernel_map_pages()
@ -2300,10 +2327,10 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
if (flags & CFLGS_OFF_SLAB) {
cachep->freelist_cache = kmalloc_slab(freelist_size, 0u);
/*
* This is a possibility for one of the malloc_sizes caches.
* This is a possibility for one of the kmalloc_{dma,}_caches.
* But since we go off slab only for object size greater than
* PAGE_SIZE/8, and malloc_sizes gets created in ascending order,
* this should not happen at all.
* PAGE_SIZE/8, and kmalloc_{dma,}_caches get created
* in ascending order,this should not happen at all.
* But leave a BUG_ON for some lucky dude.
*/
BUG_ON(ZERO_OR_NULL_PTR(cachep->freelist_cache));
@ -2511,14 +2538,17 @@ int __kmem_cache_shutdown(struct kmem_cache *cachep)
/*
* Get the memory for a slab management obj.
* For a slab cache when the slab descriptor is off-slab, slab descriptors
* always come from malloc_sizes caches. The slab descriptor cannot
* come from the same cache which is getting created because,
* when we are searching for an appropriate cache for these
* descriptors in kmem_cache_create, we search through the malloc_sizes array.
* If we are creating a malloc_sizes cache here it would not be visible to
* kmem_find_general_cachep till the initialization is complete.
* Hence we cannot have freelist_cache same as the original cache.
*
* For a slab cache when the slab descriptor is off-slab, the
* slab descriptor can't come from the same cache which is being created,
* Because if it is the case, that means we defer the creation of
* the kmalloc_{dma,}_cache of size sizeof(slab descriptor) to this point.
* And we eventually call down to __kmem_cache_create(), which
* in turn looks up in the kmalloc_{dma,}_caches for the disired-size one.
* This is a "chicken-and-egg" problem.
*
* So the off-slab slab descriptor shall come from the kmalloc_{dma,}_caches,
* which are all initialized during kmem_cache_init().
*/
static void *alloc_slabmgmt(struct kmem_cache *cachep,
struct page *page, int colour_off,
@ -2542,9 +2572,15 @@ static void *alloc_slabmgmt(struct kmem_cache *cachep,
return freelist;
}
static inline unsigned int *slab_freelist(struct page *page)
static inline freelist_idx_t get_free_obj(struct page *page, unsigned char idx)
{
return (unsigned int *)(page->freelist);
return ((freelist_idx_t *)page->freelist)[idx];
}
static inline void set_free_obj(struct page *page,
unsigned char idx, freelist_idx_t val)
{
((freelist_idx_t *)(page->freelist))[idx] = val;
}
static void cache_init_objs(struct kmem_cache *cachep,
@ -2589,7 +2625,7 @@ static void cache_init_objs(struct kmem_cache *cachep,
if (cachep->ctor)
cachep->ctor(objp);
#endif
slab_freelist(page)[i] = i;
set_free_obj(page, i, i);
}
}
@ -2608,7 +2644,7 @@ static void *slab_get_obj(struct kmem_cache *cachep, struct page *page,
{
void *objp;
objp = index_to_obj(cachep, page, slab_freelist(page)[page->active]);
objp = index_to_obj(cachep, page, get_free_obj(page, page->active));
page->active++;
#if DEBUG
WARN_ON(page_to_nid(virt_to_page(objp)) != nodeid);
@ -2629,7 +2665,7 @@ static void slab_put_obj(struct kmem_cache *cachep, struct page *page,
/* Verify double free bug */
for (i = page->active; i < cachep->num; i++) {
if (slab_freelist(page)[i] == objnr) {
if (get_free_obj(page, i) == objnr) {
printk(KERN_ERR "slab: double free detected in cache "
"'%s', objp %p\n", cachep->name, objp);
BUG();
@ -2637,7 +2673,7 @@ static void slab_put_obj(struct kmem_cache *cachep, struct page *page,
}
#endif
page->active--;
slab_freelist(page)[page->active] = objnr;
set_free_obj(page, page->active, objnr);
}
/*
@ -2886,9 +2922,9 @@ retry:
/* move slabp to correct slabp list: */
list_del(&page->lru);
if (page->active == cachep->num)
list_add(&page->list, &n->slabs_full);
list_add(&page->lru, &n->slabs_full);
else
list_add(&page->list, &n->slabs_partial);
list_add(&page->lru, &n->slabs_partial);
}
must_grow:
@ -3245,11 +3281,11 @@ slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
kmemleak_alloc_recursive(ptr, cachep->object_size, 1, cachep->flags,
flags);
if (likely(ptr))
if (likely(ptr)) {
kmemcheck_slab_alloc(cachep, flags, ptr, cachep->object_size);
if (unlikely((flags & __GFP_ZERO) && ptr))
memset(ptr, 0, cachep->object_size);
if (unlikely(flags & __GFP_ZERO))
memset(ptr, 0, cachep->object_size);
}
return ptr;
}
@ -3310,17 +3346,17 @@ slab_alloc(struct kmem_cache *cachep, gfp_t flags, unsigned long caller)
flags);
prefetchw(objp);
if (likely(objp))
if (likely(objp)) {
kmemcheck_slab_alloc(cachep, flags, objp, cachep->object_size);
if (unlikely((flags & __GFP_ZERO) && objp))
memset(objp, 0, cachep->object_size);
if (unlikely(flags & __GFP_ZERO))
memset(objp, 0, cachep->object_size);
}
return objp;
}
/*
* Caller needs to acquire correct kmem_list's list_lock
* Caller needs to acquire correct kmem_cache_node's list_lock
*/
static void free_block(struct kmem_cache *cachep, void **objpp, int nr_objects,
int node)
@ -3574,11 +3610,6 @@ static __always_inline void *__do_kmalloc(size_t size, gfp_t flags,
struct kmem_cache *cachep;
void *ret;
/* If you want to save a few bytes .text space: replace
* __ with kmem_.
* Then kmalloc uses the uninlined functions instead of the inline
* functions.
*/
cachep = kmalloc_slab(size, flags);
if (unlikely(ZERO_OR_NULL_PTR(cachep)))
return cachep;
@ -3670,7 +3701,7 @@ EXPORT_SYMBOL(kfree);
/*
* This initializes kmem_cache_node or resizes various caches for all nodes.
*/
static int alloc_kmemlist(struct kmem_cache *cachep, gfp_t gfp)
static int alloc_kmem_cache_node(struct kmem_cache *cachep, gfp_t gfp)
{
int node;
struct kmem_cache_node *n;
@ -3726,8 +3757,8 @@ static int alloc_kmemlist(struct kmem_cache *cachep, gfp_t gfp)
}
kmem_cache_node_init(n);
n->next_reap = jiffies + REAPTIMEOUT_LIST3 +
((unsigned long)cachep) % REAPTIMEOUT_LIST3;
n->next_reap = jiffies + REAPTIMEOUT_NODE +
((unsigned long)cachep) % REAPTIMEOUT_NODE;
n->shared = new_shared;
n->alien = new_alien;
n->free_limit = (1 + nr_cpus_node(node)) *
@ -3813,7 +3844,7 @@ static int __do_tune_cpucache(struct kmem_cache *cachep, int limit,
kfree(ccold);
}
kfree(new);
return alloc_kmemlist(cachep, gfp);
return alloc_kmem_cache_node(cachep, gfp);
}
static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
@ -3982,7 +4013,7 @@ static void cache_reap(struct work_struct *w)
if (time_after(n->next_reap, jiffies))
goto next;
n->next_reap = jiffies + REAPTIMEOUT_LIST3;
n->next_reap = jiffies + REAPTIMEOUT_NODE;
drain_array(searchp, n, n->shared, 0, node);
@ -4003,7 +4034,7 @@ next:
next_reap_node();
out:
/* Set up the next iteration */
schedule_delayed_work(work, round_jiffies_relative(REAPTIMEOUT_CPUC));
schedule_delayed_work(work, round_jiffies_relative(REAPTIMEOUT_AC));
}
#ifdef CONFIG_SLABINFO
@ -4210,7 +4241,7 @@ static void handle_slab(unsigned long *n, struct kmem_cache *c,
for (j = page->active; j < c->num; j++) {
/* Skip freed item */
if (slab_freelist(page)[j] == i) {
if (get_free_obj(page, j) == i) {
active = false;
break;
}

10
mm/slob.c
View File

@ -111,13 +111,13 @@ static inline int slob_page_free(struct page *sp)
static void set_slob_page_free(struct page *sp, struct list_head *list)
{
list_add(&sp->list, list);
list_add(&sp->lru, list);
__SetPageSlobFree(sp);
}
static inline void clear_slob_page_free(struct page *sp)
{
list_del(&sp->list);
list_del(&sp->lru);
__ClearPageSlobFree(sp);
}
@ -282,7 +282,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
spin_lock_irqsave(&slob_lock, flags);
/* Iterate through each partially free page, try to find room */
list_for_each_entry(sp, slob_list, list) {
list_for_each_entry(sp, slob_list, lru) {
#ifdef CONFIG_NUMA
/*
* If there's a node specification, search for a partial
@ -296,7 +296,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
continue;
/* Attempt to alloc */
prev = sp->list.prev;
prev = sp->lru.prev;
b = slob_page_alloc(sp, size, align);
if (!b)
continue;
@ -322,7 +322,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
spin_lock_irqsave(&slob_lock, flags);
sp->units = SLOB_UNITS(PAGE_SIZE);
sp->freelist = b;
INIT_LIST_HEAD(&sp->list);
INIT_LIST_HEAD(&sp->lru);
set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE));
set_slob_page_free(sp, slob_list);
b = slob_page_alloc(sp, size, align);

5
mm/slub.c
View File

@ -1352,11 +1352,12 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
page = alloc_slab_page(alloc_gfp, node, oo);
if (unlikely(!page)) {
oo = s->min;
alloc_gfp = flags;
/*
* Allocation may have failed due to fragmentation.
* Try a lower order alloc if possible
*/
page = alloc_slab_page(flags, node, oo);
page = alloc_slab_page(alloc_gfp, node, oo);
if (page)
stat(s, ORDER_FALLBACK);
@ -1366,7 +1367,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
&& !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
int pages = 1 << oo_order(oo);
kmemcheck_alloc_shadow(page, oo_order(oo), flags, node);
kmemcheck_alloc_shadow(page, oo_order(oo), alloc_gfp, node);
/*
* Objects from caches that have a constructor don't get