[dm-devel] [PATCH v2 4/4] dm: use bioset_create_nobvec()
Mike Snitzer
snitzer at redhat.com
Fri Oct 3 21:27:13 UTC 2014
From: Junichi Nomura <j-nomura at ce.jp.nec.com>
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 at ce.jp.nec.com>
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
drivers/md/dm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index aaeed99..f78ac7f 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -3021,7 +3021,7 @@ 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_nobvec_create(pool_size, front_pad);
if (!pools->bs)
goto out;
--
1.9.3
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