From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:35498 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750867AbeAKGCY (ORCPT ); Thu, 11 Jan 2018 01:02:24 -0500 From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig , Mike Snitzer , dm-devel@redhat.com Cc: Bart Van Assche , Ming Lei Subject: [PATCH V3 0/5] dm-rq: improve sequential I/O performance Date: Thu, 11 Jan 2018 14:01:54 +0800 Message-Id: <20180111060159.12991-1-ming.lei@redhat.com> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org Hi Guys, The 1st patch removes the workaround of blk_mq_delay_run_hw_queue() in case of requeue, this way isn't necessary, and more worse, it makes BLK_MQ_S_SCHED_RESTART not working, and degarde I/O performance. The 2nd patch return DM_MAPIO_REQUEUE to dm-rq if underlying request allocation fails, then we can return BLK_STS_RESOURCE from dm-rq to blk-mq, so that blk-mq can hold the requests to be dequeued. The other 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. 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 (5): dm-mpath: don't call blk_mq_delay_run_hw_queue() in case of BLK_STS_RESOURCE dm-mpath: return DM_MAPIO_REQUEUE in case of rq allocation failure 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-core.c | 3 +- block/blk-mq.c | 86 +++++++++++++++++++++++++++++++++++++++------------ block/blk-mq.h | 3 ++ drivers/md/dm-mpath.c | 19 +++++++++--- drivers/md/dm-rq.c | 20 +++++++++--- 5 files changed, 101 insertions(+), 30 deletions(-) -- 2.9.5