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| author | Mike Snitzer <snitzer@redhat.com> | 2016-09-09 19:26:19 -0400 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2016-09-15 11:16:17 -0400 |
| commit | b88efd43f900d608560211a18a38d450f8192948 (patch) | |
| tree | 417d31d35bdcda72b55882c8b0137b4799fdb6e8 /drivers/md/persistent-data | |
| parent | 7e48c768f44056a06bca596577c37f7721b53f0c (diff) | |
| download | op-kernel-dev-b88efd43f900d608560211a18a38d450f8192948.zip op-kernel-dev-b88efd43f900d608560211a18a38d450f8192948.tar.gz | |
dm mpath: delay the requeue of blk-mq requests while all paths down
Return DM_MAPIO_DELAY_REQUEUE from .clone_and_map_rq. Also, return
false from .busy, if all paths are down, so that blk-mq requests get
mapped via .clone_and_map_rq -- which results in DM_MAPIO_DELAY_REQUEUE
being returned to dm-rq.
This change allows for a noticeable reduction in cpu utilization
(reduced kworker load) while all paths are down, e.g.:
system CPU idleness (as measured by fio's --idle-prof=system):
before: system: 86.58%
after: system: 98.60%
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Diffstat (limited to 'drivers/md/persistent-data')
0 files changed, 0 insertions, 0 deletions
