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authorJunichi Nomura <j-nomura@ce.jp.nec.com>2014-10-03 11:55:26 +0000
committerMike Snitzer <snitzer@redhat.com>2014-10-05 20:03:34 -0400
commit3d8aab2d2cca2dc878e396196d07889129440798 (patch)
tree3b3e54566597979e4da22fadf80794dd72b8af51 /drivers/md/dm.c
parent997782735c0f1e2e069337129fe0d5738d83d19b (diff)
downloadlinux-3d8aab2d2cca2dc878e396196d07889129440798.tar.gz
dm: use bioset_create_nobvec()
Since DM core uses bio_clone_fast() for both bio-based and request-based
DM devices there is no need for DM's bioset to have a bvec mempool.

With this patch, on arch with 4KB page for example, memory usage will be
reduced by 64KB for each bio-based DM device and 1MB for each
request-based DM device.

For example, when you create 10,000 bio-based DM devices and 1,000
request-based DM devices, memory usage of biovec under no load is:
  # grep biovec /proc/slabinfo

  biovec-256        418068 418068   4096  ...
  biovec-128             0      0   2048  ...
  biovec-64              0      0   1024  ...
  biovec-16              0      0    256  ...

With this patch series applied, the usage becomes:
  # grep biovec /proc/slabinfo

  biovec-256           116    116   4096  ...
  biovec-128             0      0   2048  ...
  biovec-64              0      0   1024  ...
  biovec-16              0      0    256  ...

So 4096 * (418068 - 116) = 1.6GB of memory is saved in this example.

Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm.c')
-rw-r--r--drivers/md/dm.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 0b9de07d585b..56a2c74c9a3f 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2895,7 +2895,7 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u
 	if (!pools->io_pool)
 		goto out;
 
-	pools->bs = bioset_create(pool_size, front_pad);
+	pools->bs = bioset_create_nobvec(pool_size, front_pad);
 	if (!pools->bs)
 		goto out;