From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Ming Lei <ming.lei@redhat.com>,
John Garry <john.garry@huawei.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 V5 0/6] blk-mq: improvement CPU hotplug
Date: Wed, 15 Jan 2020 19:44:03 +0800 [thread overview]
Message-ID: <20200115114409.28895-1-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 inactive(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!
V5:
- rename BLK_MQ_S_INTERNAL_STOPPED as BLK_MQ_S_INACTIVE
- re-factor code for re-submit requests in cpu dead hotplug handler
- address requeue corner case
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 (6):
blk-mq: add new state of BLK_MQ_S_INACTIVE
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 inactive
blk-mq: re-submit IO in case that hctx is inactive
blk-mq: handle requests dispatched from IO scheduler in case of
inactive hctx
block: deactivate hctx when all its CPUs are offline when running
queue
block/blk-mq-debugfs.c | 2 +
block/blk-mq-tag.c | 2 +-
block/blk-mq-tag.h | 2 +
block/blk-mq.c | 172 +++++++++++++++++++++++++++++++------
block/blk-mq.h | 3 +-
drivers/block/loop.c | 2 +-
drivers/md/dm-rq.c | 2 +-
include/linux/blk-mq.h | 6 ++
include/linux/cpuhotplug.h | 1 +
9 files changed, 163 insertions(+), 29 deletions(-)
Cc: John Garry <john.garry@huawei.com>
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:[~2020-01-15 11:45 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-15 11:44 Ming Lei [this message]
2020-01-15 11:44 ` [PATCH 1/6] blk-mq: add new state of BLK_MQ_S_INACTIVE Ming Lei
2020-01-15 11:44 ` [PATCH 2/6] blk-mq: prepare for draining IO when hctx's all CPUs are offline Ming Lei
2020-01-15 11:44 ` [PATCH 3/6] blk-mq: stop to handle IO and drain IO before hctx becomes inactive Ming Lei
2020-01-15 11:44 ` [PATCH 4/6] blk-mq: re-submit IO in case that hctx is inactive Ming Lei
2020-01-15 11:44 ` [PATCH 5/6] blk-mq: handle requests dispatched from IO scheduler in case of inactive hctx Ming Lei
2020-01-15 11:44 ` [PATCH 6/6] block: deactivate hctx when all its CPUs are offline when running queue Ming Lei
2020-01-15 17:00 ` [PATCH V5 0/6] blk-mq: improvement CPU hotplug John Garry
2020-01-20 13:23 ` John Garry
2020-01-31 10:04 ` Ming Lei
2020-01-31 10:24 ` John Garry
2020-01-31 10:58 ` Ming Lei
2020-01-31 17:51 ` John Garry
2020-01-31 18:02 ` John Garry
2020-02-01 1:31 ` Ming Lei
2020-02-01 11:05 ` Marc Zyngier
2020-02-01 11:31 ` Thomas Gleixner
2020-02-03 10:30 ` John Garry
2020-02-03 10:49 ` John Garry
2020-02-03 10:59 ` Ming Lei
2020-02-03 12:56 ` John Garry
2020-02-03 15:43 ` Marc Zyngier
2020-02-03 18:16 ` John Garry
2020-02-05 14:08 ` John Garry
2020-02-05 14:23 ` Marc Zyngier
2020-02-07 10:56 ` John Garry
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