On Mon, 2018-07-02 at 17:35 +0800, Ming Lei wrote:

Hi,

The 1st 2 patch improves ctx->lock uses, and it is observed that IOPS
may be improved by ~5% in rand IO test on MegaRaid SAS run by
Kashyap.

The 3rd patch fixes rand IO performance regression on MegaRaid SAS
test, still reported by Kashyap.

V3:
	- export dispatch busy from debugfs as suggested by Jens
	- add comment on blk_mq_update_hctx_busy() as suggested by
Christoph

V2:
	- fix list corruption in patch 1/3


Ming Lei (3):
  blk-mq: use list_splice_tail_init() to insert requests
  blk-mq: only attempt to merge bio if there is rq in sw queue
  blk-mq: dequeue request one by one from sw queue iff hctx is busy

 block/blk-mq-debugfs.c |  9 +++++++++
 block/blk-mq-sched.c   | 14 ++++----------
 block/blk-mq.c         | 44 ++++++++++++++++++++++++++++++++++++--
------
 include/linux/blk-mq.h |  3 ++-
 4 files changed, 51 insertions(+), 19 deletions(-)

Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Laurence Oberman <redacted>
Cc: Omar Sandoval <redacted>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <redacted>
Cc: Hannes Reinecke <hare@suse.de>

Thanks Ming, I repaired my MSA50 shelf so will functional test.
I have 6 SSD drives working in there now. 
I know its already been tested by Kashyap.

Regards
Laurence