From: John Garry <john.garry@huawei.com>
To: Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>
Cc: <linux-block@vger.kernel.org>,
"James E . J . Bottomley" <jejb@linux.ibm.com>,
"Martin K . Petersen" <martin.petersen@oracle.com>,
<linux-scsi@vger.kernel.org>,
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: Re: [RFC PATCH 0/7] blk-mq: improvement on handling IO during CPU hotplug
Date: Tue, 16 Jul 2019 14:54:24 +0800 [thread overview]
Message-ID: <c2c83d98-2012-13af-ab46-5a28303c0f87@huawei.com> (raw)
In-Reply-To: <20190712024726.1227-1-ming.lei@redhat.com>
在 12/07/2019 10:47, Ming Lei 写道:
> 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!
>
Hi Ming,
FWIW, to me this series looks reasonable.
So you have plans to post an updated "[PATCH 0/9] blk-mq/scsi: convert
private reply queue into blk_mq hw queue" then?
All the best,
John
>
> Ming Lei (7):
> 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: add callback of .free_request
> SCSI: implement .free_request callback
> 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 | 147 ++++++++++++++++++++++++++++++++++---
> block/blk-mq.h | 3 +-
> drivers/block/loop.c | 2 +-
> drivers/md/dm-rq.c | 2 +-
> drivers/scsi/scsi_lib.c | 13 ++++
> include/linux/blk-mq.h | 12 +++
> include/linux/cpuhotplug.h | 1 +
> 10 files changed, 170 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>
>
>
next prev parent reply other threads:[~2019-07-16 6:54 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-12 2:47 [RFC PATCH 0/7] blk-mq: improvement on handling IO during CPU hotplug Ming Lei
2019-07-12 2:47 ` [RFC PATCH 1/7] blk-mq: add new state of BLK_MQ_S_INTERNAL_STOPPED Ming Lei
2019-07-12 2:47 ` [RFC PATCH 2/7] blk-mq: add blk-mq flag of BLK_MQ_F_NO_MANAGED_IRQ Ming Lei
2019-07-16 2:53 ` John Garry
2019-07-16 6:08 ` Ming Lei
2019-07-12 2:47 ` [RFC PATCH 3/7] blk-mq: stop to handle IO before hctx's all CPUs become offline Ming Lei
2019-07-12 9:03 ` Minwoo Im
2019-07-16 3:03 ` John Garry
2019-07-16 6:12 ` Ming Lei
2019-07-12 2:47 ` [RFC PATCH 4/7] blk-mq: add callback of .free_request Ming Lei
2019-07-12 2:47 ` [RFC PATCH 5/7] SCSI: implement .free_request callback Ming Lei
2019-07-12 2:47 ` [RFC PATCH 6/7] blk-mq: re-submit IO in case that hctx is dead Ming Lei
2019-07-12 2:47 ` [RFC PATCH 7/7] blk-mq: handle requests dispatched from IO scheduler " Ming Lei
2019-07-16 6:54 ` John Garry [this message]
2019-07-16 7:18 ` [RFC PATCH 0/7] blk-mq: improvement on handling IO during CPU hotplug Ming Lei
2019-07-16 8:13 ` John Garry
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