Hi,

This v2 the product of more thorough review and testing (on my part)
of Mikulas' original patchset.

Not seeing a major performance win in general but no loss either.  DM
devices do see a huge boost in IOPS thanks to being able to eliminate
the inefficient md->pending IO accounting that it was doing, see:
https://www.redhat.com/archives/dm-devel/2018-November/msg00415.html

Happy to iterate on this patchset further as needed, all
review/suggestions are very much appreciated.

Thanks,
Mike

Mike Snitzer (1):
  dm rq: leverage blk_mq_queue_busy() to check for outstanding IO

Mikulas Patocka (5):
  dm: dont rewrite dm_disk(md)->part0.in_flight
  block: delete part_round_stats and switch to less precise counting
  block: switch to per-cpu in-flight counters
  block: return just one value from part_in_flight
  dm: remove the pending IO accounting

 block/bio.c               | 28 ++++++++++++++++----
 block/blk-core.c          | 67 +++++------------------------------------------
 block/blk-merge.c         |  3 +--
 block/blk-mq.c            | 12 ++++-----
 block/blk-mq.h            |  3 +--
 block/genhd.c             | 59 +++++++++++++++++++++++------------------
 block/partition-generic.c | 10 +++----
 drivers/md/dm-core.h      |  2 --
 drivers/md/dm-rq.c        |  9 +++----
 drivers/md/dm.c           | 36 +++++++++++--------------
 include/linux/genhd.h     | 13 +++++----
 11 files changed, 98 insertions(+), 144 deletions(-)

-- 
2.15.0