Skip to content

Commit

Permalink
[BLOCK] Don't pin lots of memory in mempools
Browse files Browse the repository at this point in the history 
Currently we scale the mempool sizes depending on memory installed
in the machine, except for the bio pool itself which sits at a fixed
256 entry pre-allocation.

There's really no point in "optimizing" this OOM path, we just need
enough preallocated to make progress. A single unit is enough, lets
scale it down to 2 just to be on the safe side.

This patch saves ~150kb of pinned kernel memory on a 32-bit box.

Signed-off-by: Jens Axboe <[email protected]>
  • Loading branch information
Jens Axboe authored and Jens Axboe committed Apr 30, 2007
1 parent b9099ff commit 5972511
Show file tree
Hide file tree
Showing 6 changed files with 11 additions and 40 deletions.
2 changes: 1 addition & 1 deletion drivers/md/dm-crypt.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -867,7 +867,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
goto bad4;
}

cc->bs = bioset_create(MIN_IOS, MIN_IOS, 4);
cc->bs = bioset_create(MIN_IOS, MIN_IOS);
if (!cc->bs) {
ti->error = "Cannot allocate crypt bioset";
goto bad_bs;
Expand Down
2 changes: 1 addition & 1 deletion drivers/md/dm-io.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -60,7 +60,7 @@ static int resize_pool(unsigned int new_ios)
if (!_io_pool)
return -ENOMEM;

_bios = bioset_create(16, 16, 4);
_bios = bioset_create(16, 16);
if (!_bios) {
mempool_destroy(_io_pool);
_io_pool = NULL;
Expand Down
2 changes: 1 addition & 1 deletion drivers/md/dm.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1012,7 +1012,7 @@ static struct mapped_device *alloc_dev(int minor)
if (!md->tio_pool)
goto bad3;

md->bs = bioset_create(16, 16, 4);
md->bs = bioset_create(16, 16);
if (!md->bs)
goto bad_no_bioset;

Expand Down
2 changes: 1 addition & 1 deletion drivers/scsi/scsi_lib.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@


#define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
#define SG_MEMPOOL_SIZE 32
#define SG_MEMPOOL_SIZE 2

struct scsi_host_sg_pool {
size_t size;
Expand Down
41 changes: 6 additions & 35 deletions fs/bio.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@
#include <linux/blktrace_api.h>
#include <scsi/sg.h> /* for struct sg_iovec */

#define BIO_POOL_SIZE 256
#define BIO_POOL_SIZE 2

static struct kmem_cache *bio_slab __read_mostly;

Expand All @@ -38,7 +38,7 @@ static struct kmem_cache *bio_slab __read_mostly;
* a small number of entries is fine, not going to be performance critical.
* basically we just need to survive
*/
#define BIO_SPLIT_ENTRIES 8
#define BIO_SPLIT_ENTRIES 2
mempool_t *bio_split_pool __read_mostly;

struct biovec_slab {
Expand Down Expand Up @@ -1120,17 +1120,14 @@ struct bio_pair *bio_split(struct bio *bi, mempool_t *pool, int first_sectors)
* create memory pools for biovec's in a bio_set.
* use the global biovec slabs created for general use.
*/
static int biovec_create_pools(struct bio_set *bs, int pool_entries, int scale)
static int biovec_create_pools(struct bio_set *bs, int pool_entries)
{
int i;

for (i = 0; i < BIOVEC_NR_POOLS; i++) {
struct biovec_slab *bp = bvec_slabs + i;
mempool_t **bvp = bs->bvec_pools + i;

if (pool_entries > 1 && i >= scale)
pool_entries >>= 1;

*bvp = mempool_create_slab_pool(pool_entries, bp->slab);
if (!*bvp)
return -ENOMEM;
Expand Down Expand Up @@ -1161,7 +1158,7 @@ void bioset_free(struct bio_set *bs)
kfree(bs);
}

struct bio_set *bioset_create(int bio_pool_size, int bvec_pool_size, int scale)
struct bio_set *bioset_create(int bio_pool_size, int bvec_pool_size)
{
struct bio_set *bs = kzalloc(sizeof(*bs), GFP_KERNEL);

Expand All @@ -1172,7 +1169,7 @@ struct bio_set *bioset_create(int bio_pool_size, int bvec_pool_size, int scale)
if (!bs->bio_pool)
goto bad;

if (!biovec_create_pools(bs, bvec_pool_size, scale))
if (!biovec_create_pools(bs, bvec_pool_size))
return bs;

bad:
Expand All @@ -1196,38 +1193,12 @@ static void __init biovec_init_slabs(void)

static int __init init_bio(void)
{
int megabytes, bvec_pool_entries;
int scale = BIOVEC_NR_POOLS;

bio_slab = kmem_cache_create("bio", sizeof(struct bio), 0,
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);

biovec_init_slabs();

megabytes = nr_free_pages() >> (20 - PAGE_SHIFT);

/*
* find out where to start scaling
*/
if (megabytes <= 16)
scale = 0;
else if (megabytes <= 32)
scale = 1;
else if (megabytes <= 64)
scale = 2;
else if (megabytes <= 96)
scale = 3;
else if (megabytes <= 128)
scale = 4;

/*
* Limit number of entries reserved -- mempools are only used when
* the system is completely unable to allocate memory, so we only
* need enough to make progress.
*/
bvec_pool_entries = 1 + scale;

fs_bio_set = bioset_create(BIO_POOL_SIZE, bvec_pool_entries, scale);
fs_bio_set = bioset_create(BIO_POOL_SIZE, 2);
if (!fs_bio_set)
panic("bio: can't allocate bios\n");

Expand Down
2 changes: 1 addition & 1 deletion include/linux/bio.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -276,7 +276,7 @@ extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool,
extern mempool_t *bio_split_pool;
extern void bio_pair_release(struct bio_pair *dbio);

extern struct bio_set *bioset_create(int, int, int);
extern struct bio_set *bioset_create(int, int);
extern void bioset_free(struct bio_set *);

extern struct bio *bio_alloc(gfp_t, int);
Expand Down

0 comments on commit 5972511

Please sign in to comment.