From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Minwoo Im <minwoo.im.dev@gmail.com>,
Ming Lei <ming.lei@redhat.com>,
Bart Van Assche <bvanassche@acm.org>,
Hannes Reinecke <hare@suse.com>, Christoph Hellwig <hch@lst.de>,
Thomas Gleixner <tglx@linutronix.de>,
Keith Busch <keith.busch@intel.com>
Subject: [PATCH V2 0/5] blk-mq: improvement on handling IO during CPU hotplug
Date: Mon, 12 Aug 2019 21:43:07 +0800 [thread overview]
Message-ID: <20190812134312.16732-1-ming.lei@redhat.com> (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!
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: add blk-mq flag of BLK_MQ_F_NO_MANAGED_IRQ
blk-mq: stop to handle IO before hctx's all CPUs become offline
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 | 143 +++++++++++++++++++++++++++++++++----
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, 146 insertions(+), 16 deletions(-)
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Keith Busch <keith.busch@intel.com>
--
2.20.1
next reply other threads:[~2019-08-12 13:43 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-12 13:43 Ming Lei [this message]
2019-08-12 13:43 ` [PATCH V2 1/5] blk-mq: add new state of BLK_MQ_S_INTERNAL_STOPPED Ming Lei
2019-08-12 13:43 ` [PATCH V2 2/5] blk-mq: add blk-mq flag of BLK_MQ_F_NO_MANAGED_IRQ Ming Lei
2019-08-12 13:43 ` [PATCH V2 3/5] blk-mq: stop to handle IO before hctx's all CPUs become offline Ming Lei
2019-08-12 14:24 ` Hannes Reinecke
2019-08-12 22:24 ` Ming Lei
2019-08-12 13:43 ` [PATCH V2 4/5] blk-mq: re-submit IO in case that hctx is dead Ming Lei
2019-08-12 14:26 ` Hannes Reinecke
2019-08-12 22:30 ` Ming Lei
2019-08-12 13:43 ` [PATCH V2 5/5] blk-mq: handle requests dispatched from IO scheduler " Ming Lei
2019-08-12 13:46 ` [PATCH V2 0/5] blk-mq: improvement on handling IO during CPU hotplug Ming Lei
2019-08-12 16:21 ` John Garry
2019-08-12 22:45 ` Ming Lei
2019-08-22 17:39 ` John Garry
2019-10-02 9:56 ` John Garry
2019-10-02 14:36 ` Jens Axboe
2019-10-06 2:47 ` Ming Lei
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