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From: John Garry <john.garry@huawei.com>
To: Christoph Hellwig <hch@lst.de>
Cc: <linux-block@vger.kernel.org>,
	Bart Van Assche <bvanassche@acm.org>,
	Hannes Reinecke <hare@suse.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: blk-mq: improvement CPU hotplug (simplified version) v2
Date: Mon, 18 May 2020 12:49:14 +0100
Message-ID: <6241656e-0bf7-b32d-493e-e3f870a4d031@huawei.com> (raw)
In-Reply-To: <20200518063937.757218-1-hch@lst.de>

On 18/05/2020 07:39, Christoph Hellwig wrote:
> Hi all,
> 
> this series ensures I/O is quiesced before a cpu and thus the managed
> interrupt handler is shut down.
> 
> This patchset tries to address the issue by the following approach:
> 
>   - before the last cpu in hctx->cpumask is going to offline, mark this
>     hctx as inactive
> 
>   - disable preempt during allocating tag for request, and after tag is
>     allocated, check if this hctx is inactive. If yes, give up the
>     allocation and try remote allocation from online CPUs
> 
>   - before hctx becomes inactive, drain all allocated requests on this
>     hctx
> 
> The guts of the changes are from Ming Lei, I just did a bunch of prep
> cleanups so that they can fit in more nicely.  The series also depends
> on my "avoid a few q_usage_counter roundtrips v3" series.
> 
> Thanks John Garry for running lots of tests on arm64 with this previous
> version patches and co-working on investigating all kinds of issues.
> 
> A git tree is available here:
> 
>      git://git.infradead.org/users/hch/block.git blk-mq-hotplug
> 
> Gitweb:
> 
>      http://git.infradead.org/users/hch/block.git/shortlog/refs/heads/blk-mq-hotplug
> .
> 

FWIW, I tested this series for cpu hotplug and it looked ok.

john

  parent reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-18  6:39 Christoph Hellwig
2020-05-18  6:39 ` [PATCH 1/9] blk-mq: split out a __blk_mq_get_driver_tag helper Christoph Hellwig
2020-05-18  6:39 ` [PATCH 2/9] blk-mq: remove the bio argument to ->prepare_request Christoph Hellwig
2020-05-18  6:39 ` [PATCH 3/9] blk-mq: simplify the blk_mq_get_request calling convention Christoph Hellwig
2020-05-18  6:39 ` [PATCH 4/9] blk-mq: merge blk_mq_rq_ctx_init into __blk_mq_alloc_request Christoph Hellwig
2020-05-18  6:39 ` [PATCH 5/9] blk-mq: don't set data->ctx and data->hctx in blk_mq_alloc_request_hctx Christoph Hellwig
2020-05-18  8:32   ` Thomas Gleixner
2020-05-18  9:31     ` Ming Lei
2020-05-18 10:42       ` Thomas Gleixner
2020-05-18 11:54         ` Ming Lei
2020-05-18 13:16           ` Christoph Hellwig
2020-05-18 14:11             ` Ming Lei
2020-05-18 16:56               ` Christoph Hellwig
2020-05-18 18:38                 ` Thomas Gleixner
2020-05-18 18:45                   ` Christoph Hellwig
2020-05-18 18:59                     ` Thomas Gleixner
2020-05-19  1:54                 ` Ming Lei
2020-05-19 15:30                   ` Christoph Hellwig
2020-05-20  1:18                     ` Ming Lei
2020-05-20  3:04                       ` Ming Lei
2020-05-20  8:03                         ` io_uring vs CPU hotplug, was " Christoph Hellwig
2020-05-20 14:45                           ` Jens Axboe
2020-05-20 15:20                             ` Jens Axboe
2020-05-20 15:31                               ` Christoph Hellwig
2020-05-20 19:41                               ` Thomas Gleixner
2020-05-20 20:18                                 ` Jens Axboe
2020-05-20 22:14                                   ` Thomas Gleixner
2020-05-20 22:40                                     ` Jens Axboe
2020-05-21  2:27                                     ` Ming Lei
2020-05-21  8:13                                       ` Thomas Gleixner
2020-05-21  9:23                                         ` Ming Lei
2020-05-21 18:39                                           ` Thomas Gleixner
2020-05-21 18:45                                             ` Jens Axboe
2020-05-21 20:00                                               ` Thomas Gleixner
2020-05-22  1:57                                             ` Ming Lei
2020-05-18 18:47             ` Thomas Gleixner
2020-05-18 13:18           ` Thomas Gleixner
2020-05-18  6:39 ` [PATCH 6/9] blk-mq: don't set data->ctx and data->hctx in __blk_mq_alloc_request Christoph Hellwig
2020-05-18  6:39 ` [PATCH 7/9] blk-mq: disable preemption during allocating request tag Christoph Hellwig
2020-05-18  6:39 ` [PATCH 8/9] blk-mq: add blk_mq_all_tag_iter Christoph Hellwig
2020-05-18  6:39 ` [PATCH 9/9] blk-mq: drain I/O when all CPUs in a hctx are offline Christoph Hellwig
2020-05-18  8:42   ` John Garry
2020-05-18  9:21     ` Ming Lei
2020-05-18 11:49 ` John Garry [this message]
2020-05-19 15:30   ` blk-mq: improvement CPU hotplug (simplified version) v2 Christoph Hellwig
2020-05-19 17:17     ` John Garry
2020-05-20 14:35     ` John Garry

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