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>
1 file changed