From: Sagi Grimberg <sagi@grimberg.me>
To: Keith Busch <kbusch@kernel.org>, Chao Leng <lengchao@huawei.com>
Cc: axboe@fb.com, hch@lst.de, linux-nvme@lists.infradead.org
Subject: Re: [PATCH] nvme-core: reduce io pause time when fail over
Date: Wed, 22 Jul 2020 09:13:29 -0700 [thread overview]
Message-ID: <973d6470-05e8-8be4-2c8b-3162f37a971e@grimberg.me> (raw)
In-Reply-To: <20200722160054.GA1363519@dhcp-10-100-145-180.wdl.wdc.com>
>> To reduce io pause time, nvme_stop_queues use
>> blk_mq_quiesce_queue_nowait to quiesce the queue, nvme_stop_queues wait
>> all ongoing dispatches completed after all queues has been quiesced.
>
> The comment above blk_mq_quiesce_queue_nowait() wants to remove this
> function. I'm not sure we should be introducing more users if that's the
> case.
>
> Using synchronize_rcu() at the end may be looking to much into blk-mq's
> internal quiesce implementation. It happens to be the right thing to do
> for non-blocking hctx, so this patch assumes that will be true for any
> nvme request_queue.
nvme-tcp became a block hctx since we optimize to do network sends from
inside queue_rq. So this should either split into two functions or
nvme-core needs to look into BLK_MQ_F_BLOCKING and do the right thing.
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next prev parent reply other threads:[~2020-07-22 16:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-22 9:36 [PATCH] nvme-core: reduce io pause time when fail over Chao Leng
2020-07-22 16:00 ` Keith Busch
2020-07-22 16:13 ` Sagi Grimberg [this message]
2020-07-23 8:06 ` Chao Leng
2020-07-23 16:30 ` Sagi Grimberg
2020-07-23 16:42 ` Keith Busch
2020-07-23 19:12 ` Sagi Grimberg
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