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>
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@ -145,6 +145,8 @@ struct dm_raid1_read_record {
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struct dm_bio_details details;
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struct dm_bio_details details;
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};
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};
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static struct kmem_cache *_dm_raid1_read_record_cache;
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/*
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/*
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* Every mirror should look like this one.
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* Every mirror should look like this one.
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*/
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*/
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@ -764,9 +766,9 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
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atomic_set(&ms->suspend, 0);
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atomic_set(&ms->suspend, 0);
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atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
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atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
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len = sizeof(struct dm_raid1_read_record);
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ms->read_record_pool = mempool_create_slab_pool(MIN_READ_RECORDS,
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ms->read_record_pool = mempool_create_kmalloc_pool(MIN_READ_RECORDS,
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_dm_raid1_read_record_cache);
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len);
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if (!ms->read_record_pool) {
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if (!ms->read_record_pool) {
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ti->error = "Error creating mirror read_record_pool";
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ti->error = "Error creating mirror read_record_pool";
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kfree(ms);
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kfree(ms);
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@ -1279,16 +1281,31 @@ static int __init dm_mirror_init(void)
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{
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{
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int r;
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int r;
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r = dm_register_target(&mirror_target);
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_dm_raid1_read_record_cache = KMEM_CACHE(dm_raid1_read_record, 0);
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if (r < 0)
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if (!_dm_raid1_read_record_cache) {
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DMERR("Failed to register mirror target");
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DMERR("Can't allocate dm_raid1_read_record cache");
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r = -ENOMEM;
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goto bad_cache;
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}
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r = dm_register_target(&mirror_target);
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if (r < 0) {
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DMERR("Failed to register mirror target");
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goto bad_target;
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}
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return 0;
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bad_target:
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kmem_cache_destroy(_dm_raid1_read_record_cache);
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bad_cache:
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return r;
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return r;
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}
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}
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static void __exit dm_mirror_exit(void)
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static void __exit dm_mirror_exit(void)
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{
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{
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dm_unregister_target(&mirror_target);
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dm_unregister_target(&mirror_target);
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kmem_cache_destroy(_dm_raid1_read_record_cache);
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}
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}
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/* Module hooks */
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/* Module hooks */
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