From 5972511b77809cb7c9ccdb79b825c54921c5c546 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 2 Apr 2007 10:06:42 +0200 Subject: [BLOCK] Don't pin lots of memory in mempools 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 --- fs/bio.c | 41 ++++++----------------------------------- 1 file changed, 6 insertions(+), 35 deletions(-) (limited to 'fs') diff --git a/fs/bio.c b/fs/bio.c index 7618bcb18368..693940da4090 100644 --- a/fs/bio.c +++ b/fs/bio.c @@ -28,7 +28,7 @@ #include #include /* for struct sg_iovec */ -#define BIO_POOL_SIZE 256 +#define BIO_POOL_SIZE 2 static struct kmem_cache *bio_slab __read_mostly; @@ -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 { @@ -1120,7 +1120,7 @@ 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; @@ -1128,9 +1128,6 @@ static int biovec_create_pools(struct bio_set *bs, int pool_entries, int scale) 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; @@ -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); @@ -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: @@ -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"); -- cgit v1.2.3-59-g8ed1b