From: "jianchao.wang" <jianchao.w.wang@oracle.com>
To: Bart Van Assche <bvanassche@acm.org>,
axboe@kernel.dk, ming.lei@redhat.com, bart.vanassche@wdc.com,
sagi@grimberg.me, keith.busch@intel.com, jthumshirn@suse.de,
jsmart2021@gmail.com
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-nvme@lists.infradead.org
Subject: Re: [PATCH 2/3] blk-core: introduce queue close feature
Date: Thu, 6 Sep 2018 09:31:06 +0800 [thread overview]
Message-ID: <ccf20c21-880a-98ca-b111-8e6b82b47a11@oracle.com> (raw)
In-Reply-To: <1536163037.11534.6.camel@acm.org>
Hi Bart
On 09/05/2018 11:57 PM, Bart Van Assche wrote:
> On Wed, 2018-09-05 at 12:09 +0800, Jianchao Wang wrote:
>> blk queue freeze is often used to prevent new IO from entering
>> request queue. However, becuase we kill the percpu-ref
>> q_usage_counter when freeze queue, we have to drain the request
>> queue when unfreeze. This is unnecessary for just preventing new
>> IO. In addition, If there is IO timeout or other issue when unfreeze
>> the queue, the scenario could be very tricky.
>>
>> So we introduce BLK_QUEUE_GATE_CLOSED to implement a light-weight
>> queue close feature base on the queue_gate to prevent new IO from
>> comming in queue which will not need to drain the queue any more.
>
> Does the "queue gate close" feature cause blk_get_request() /
> blk_mq_get_request() to block until blk_clear_queue_closed() is called?
Yes. It works in blk_queue_enter. So it could cover blk_mq_get_request
If
> so, I think we need a better name for this feature. How about calling these
> two operations suspend and resume?
I'm open for it. :)
>
> Thanks,
>
> Bart.
>
next prev parent reply other threads:[~2018-09-06 1:30 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-05 4:09 [PATCH 0/3] Introduce a light-weight queue close feature Jianchao Wang
2018-09-05 4:09 ` [PATCH 1/3] blk-core: migrate preempt-only mode to queue_gate Jianchao Wang
2018-09-05 4:09 ` [PATCH 2/3] blk-core: introduce queue close feature Jianchao Wang
2018-09-05 15:57 ` Bart Van Assche
2018-09-06 1:31 ` jianchao.wang [this message]
2018-09-05 4:09 ` [PATCH 3/3] nvme-pci: use queue close instead of queue freeze Jianchao Wang
2018-09-05 22:09 ` Ming Lei
2018-09-06 1:28 ` jianchao.wang
2018-09-06 13:07 ` Ming Lei
2018-09-06 14:19 ` jianchao.wang
2018-09-07 16:23 ` Ming Lei
2018-09-10 1:49 ` jianchao.wang
2018-09-05 15:48 ` [PATCH 0/3] Introduce a light-weight queue close feature Bart Van Assche
2018-09-06 1:35 ` jianchao.wang
2018-09-05 21:27 ` Ming Lei
2018-09-06 1:51 ` jianchao.wang
2018-09-06 12:57 ` Ming Lei
2018-09-06 13:55 ` jianchao.wang
2018-09-07 16:21 ` Ming Lei
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