Hi Guys, The 3 paches changes the blk-mq part of blk_insert_cloned_request(), in which we switch to blk_mq_try_issue_directly(), so that both dm-rq and blk-mq can get the dispatch result of underlying queue, and with this information, blk-mq can handle IO merge much better, then sequential I/O performance is improved much. In my dm-mpath over virtio-scsi test, this whole patchset improves sequential IO by 3X ~ 5X. V4: - remove dm patches which are in DM tree already - cleanup __blk_mq_issue_req as suggested by Jens V3: - rebase on the latest for-4.16/block of block tree - add missed pg_init_all_paths() in patch 1, according to Bart's review V2: - drop 'dm-mpath: cache ti->clone during requeue', which is a bit too complicated, and not see obvious performance improvement. - make change on blk-mq part cleaner Ming Lei (3): blk-mq: move actual issue into one helper blk-mq: return dispatch result to caller in blk_mq_try_issue_directly blk-mq: issue request directly for blk_insert_cloned_request block/blk-mq.c | 85 +++++++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 64 insertions(+), 21 deletions(-) -- 2.9.5
