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authorMikulas Patocka <mpatocka@redhat.com>2009-04-02 14:55:24 -0400
committerAlasdair G Kergon <agk@redhat.com>2009-04-02 14:55:24 -0400
commit95f8fac8dc6139fedfb87746e0c8fda9b803cb46 (patch)
tree36c980967ee188865d0a58be2e1281b5bf77cbae /drivers/md/dm-raid1.c
parenta920f6b3accc77d9dddbc98a7426be23ee479625 (diff)
dm raid1: switch read_record from kmalloc to slab to save memory
With my previous patch to save bi_io_vec, the size of dm_raid1_read_record is significantly increased (the vector list takes 3072 bytes on 32-bit machines and 4096 bytes on 64-bit machines). The structure dm_raid1_read_record used to be allocated with kmalloc, but kmalloc aligns the size on the next power-of-two so an object slightly greater than 4096 will allocate 8192 bytes of memory and half of that memory will be wasted. This patch turns kmalloc into a slab cache which doesn't have this padding so it will reduce the memory consumed. Cc: stable@kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-raid1.c')
-rw-r--r--drivers/md/dm-raid1.c25
1 files changed, 21 insertions, 4 deletions
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 4d6bc101962e..62d594889ac3 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -145,6 +145,8 @@ struct dm_raid1_read_record {
145 struct dm_bio_details details; 145 struct dm_bio_details details;
146}; 146};
147 147
148static struct kmem_cache *_dm_raid1_read_record_cache;
149
148/* 150/*
149 * Every mirror should look like this one. 151 * Every mirror should look like this one.
150 */ 152 */
@@ -764,9 +766,9 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
764 atomic_set(&ms->suspend, 0); 766 atomic_set(&ms->suspend, 0);
765 atomic_set(&ms->default_mirror, DEFAULT_MIRROR); 767 atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
766 768
767 len = sizeof(struct dm_raid1_read_record); 769 ms->read_record_pool = mempool_create_slab_pool(MIN_READ_RECORDS,
768 ms->read_record_pool = mempool_create_kmalloc_pool(MIN_READ_RECORDS, 770 _dm_raid1_read_record_cache);
769 len); 771
770 if (!ms->read_record_pool) { 772 if (!ms->read_record_pool) {
771 ti->error = "Error creating mirror read_record_pool"; 773 ti->error = "Error creating mirror read_record_pool";
772 kfree(ms); 774 kfree(ms);
@@ -1279,16 +1281,31 @@ static int __init dm_mirror_init(void)
1279{ 1281{
1280 int r; 1282 int r;
1281 1283
1284 _dm_raid1_read_record_cache = KMEM_CACHE(dm_raid1_read_record, 0);
1285 if (!_dm_raid1_read_record_cache) {
1286 DMERR("Can't allocate dm_raid1_read_record cache");
1287 r = -ENOMEM;
1288 goto bad_cache;
1289 }
1290
1282 r = dm_register_target(&mirror_target); 1291 r = dm_register_target(&mirror_target);
1283 if (r < 0) 1292 if (r < 0) {
1284 DMERR("Failed to register mirror target"); 1293 DMERR("Failed to register mirror target");
1294 goto bad_target;
1295 }
1296
1297 return 0;
1285 1298
1299bad_target:
1300 kmem_cache_destroy(_dm_raid1_read_record_cache);
1301bad_cache:
1286 return r; 1302 return r;
1287} 1303}
1288 1304
1289static void __exit dm_mirror_exit(void) 1305static void __exit dm_mirror_exit(void)
1290{ 1306{
1291 dm_unregister_target(&mirror_target); 1307 dm_unregister_target(&mirror_target);
1308 kmem_cache_destroy(_dm_raid1_read_record_cache);
1292} 1309}
1293 1310
1294/* Module hooks */ 1311/* Module hooks */