From: Ming Lei <firstname.lastname@example.org> To: Jens Axboe <email@example.com> Cc: firstname.lastname@example.org, Ming Lei <email@example.com>, John Garry <firstname.lastname@example.org>, Bart Van Assche <email@example.com>, Hannes Reinecke <firstname.lastname@example.org>, Christoph Hellwig <email@example.com>, Thomas Gleixner <firstname.lastname@example.org>, Keith Busch <email@example.com> Subject: [PATCH V4 0/5] blk-mq: improvement on handling IO during CPU hotplug Date: Mon, 14 Oct 2019 09:50:38 +0800 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) Hi, Thomas mentioned: " That was the constraint of managed interrupts from the very beginning: The driver/subsystem has to quiesce the interrupt line and the associated queue _before_ it gets shutdown in CPU unplug and not fiddle with it until it's restarted by the core when the CPU is plugged in again. " But no drivers or blk-mq do that before one hctx becomes dead(all CPUs for one hctx are offline), and even it is worse, blk-mq stills tries to run hw queue after hctx is dead, see blk_mq_hctx_notify_dead(). This patchset tries to address the issue by two stages: 1) add one new cpuhp state of CPUHP_AP_BLK_MQ_ONLINE - mark the hctx as internal stopped, and drain all in-flight requests if the hctx is going to be dead. 2) re-submit IO in the state of CPUHP_BLK_MQ_DEAD after the hctx becomes dead - steal bios from the request, and resubmit them via generic_make_request(), then these IO will be mapped to other live hctx for dispatch Please comment & review, thanks! John, I don't add your tested-by tag since V3 have some changes, and I appreciate if you may run your test on V3. V4: - resubmit IOs in dispatch list in case that this hctx is dead V3: - re-organize patch 2 & 3 a bit for addressing Hannes's comment - fix patch 4 for avoiding potential deadlock, as found by Hannes V2: - patch4 & patch 5 in V1 have been merged to block tree, so remove them - address comments from John Garry and Minwoo Ming Lei (5): blk-mq: add new state of BLK_MQ_S_INTERNAL_STOPPED blk-mq: prepare for draining IO when hctx's all CPUs are offline blk-mq: stop to handle IO and drain IO before hctx becomes dead blk-mq: re-submit IO in case that hctx is dead blk-mq: handle requests dispatched from IO scheduler in case that hctx is dead block/blk-mq-debugfs.c | 2 + block/blk-mq-tag.c | 2 +- block/blk-mq-tag.h | 2 + block/blk-mq.c | 137 ++++++++++++++++++++++++++++++++++--- block/blk-mq.h | 3 +- drivers/block/loop.c | 2 +- drivers/md/dm-rq.c | 2 +- include/linux/blk-mq.h | 5 ++ include/linux/cpuhotplug.h | 1 + 9 files changed, 141 insertions(+), 15 deletions(-) Cc: John Garry <email@example.com> Cc: Bart Van Assche <firstname.lastname@example.org> Cc: Hannes Reinecke <email@example.com> Cc: Christoph Hellwig <firstname.lastname@example.org> Cc: Thomas Gleixner <email@example.com> Cc: Keith Busch <firstname.lastname@example.org> -- 2.20.1
next reply other threads:[~2019-10-14 1:50 UTC|newest] Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-10-14 1:50 Ming Lei [this message] 2019-10-14 1:50 ` [PATCH V4 1/5] blk-mq: add new state of BLK_MQ_S_INTERNAL_STOPPED Ming Lei 2019-10-14 1:50 ` [PATCH V4 2/5] blk-mq: prepare for draining IO when hctx's all CPUs are offline Ming Lei 2019-10-14 1:50 ` [PATCH V4 3/5] blk-mq: stop to handle IO and drain IO before hctx becomes dead Ming Lei 2019-11-28 9:29 ` John Garry 2019-10-14 1:50 ` [PATCH V4 4/5] blk-mq: re-submit IO in case that hctx is dead Ming Lei 2019-10-14 1:50 ` [PATCH V4 5/5] blk-mq: handle requests dispatched from IO scheduler " Ming Lei 2019-10-16 8:58 ` [PATCH V4 0/5] blk-mq: improvement on handling IO during CPU hotplug John Garry 2019-10-16 12:07 ` Ming Lei 2019-10-16 16:19 ` John Garry [not found] ` <email@example.com> 2019-10-20 10:14 ` Ming Lei 2019-10-21 9:19 ` John Garry 2019-10-21 9:34 ` Ming Lei 2019-10-21 9:47 ` John Garry 2019-10-21 10:24 ` Ming Lei 2019-10-21 11:49 ` John Garry 2019-10-21 12:53 ` Ming Lei 2019-10-21 14:02 ` John Garry 2019-10-22 0:16 ` Ming Lei 2019-10-22 11:19 ` John Garry 2019-10-22 13:45 ` Ming Lei 2019-10-25 16:33 ` John Garry 2019-10-28 10:42 ` Ming Lei 2019-10-28 11:55 ` John Garry 2019-10-29 1:50 ` Ming Lei 2019-10-29 9:22 ` John Garry 2019-10-29 10:05 ` Ming Lei 2019-10-29 17:54 ` John Garry 2019-10-31 16:28 ` John Garry 2019-11-28 1:09 ` chenxiang (M) 2019-11-28 2:02 ` Ming Lei 2019-11-28 10:45 ` John Garry
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --subject='Re: [PATCH V4 0/5] blk-mq: improvement on handling IO during CPU hotplug' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).