From: Keith Busch <kbusch@kernel.org>
To: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: axboe@kernel.dk, hch@lst.de, jthumshirn@suse.de, hare@suse.de,
josef@toxicpanda.com, bvanassche@acm.org, sagi@grimberg.me,
keith.busch@intel.com, jsmart2021@gmail.com,
linux-block@vger.kernel.org, linux-nvme@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH V2 7/8] nvme: use blk_mq_queue_tag_inflight_iter
Date: Mon, 25 Mar 2019 07:49:18 -0600 [thread overview]
Message-ID: <20190325134917.GA4328@localhost.localdomain> (raw)
In-Reply-To: <1553492318-1810-8-git-send-email-jianchao.w.wang@oracle.com>
On Mon, Mar 25, 2019 at 01:38:37PM +0800, Jianchao Wang wrote:
> blk_mq_tagset_inflight_iter is not safe that it could get stale request
> in tags->rqs[]. Use blk_mq_queue_tag_inflight_iter here. A new helper
> interface nvme_iterate_inflight_rqs is introduced to iterate
> all of the ns under a ctrl.
Nak, NVMe only iterates tags when new requests can't enter, allocated
requests can't dispatch, and dispatched commands can't complete. So
it is perfectly safe to iterate if the driver takes reasonable steps
beforehand. Further, for M tags and N namespaces, we complete teardown
in O(M) time, but this makes in O(M*N) without gaining anything.
next prev parent reply other threads:[~2019-03-25 13:48 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-25 5:38 [PATCH V2 0/8]: blk-mq: use static_rqs to iterate busy tags Jianchao Wang
2019-03-25 5:38 ` [PATCH V2 1/8] blk-mq: get rid of the synchronize_rcu in __blk_mq_update_nr_hw_queues Jianchao Wang
2019-03-25 5:38 ` [PATCH V2 2/8] blk-mq: use static_rqs instead of rqs to iterate tags Jianchao Wang
2019-03-25 7:12 ` Dongli Zhang
2019-03-25 7:14 ` jianchao.wang
2019-03-25 5:38 ` [PATCH V2 3/8] blk-mq: use blk_mq_queue_tag_inflight_iter in debugfs Jianchao Wang
2019-03-25 5:38 ` [PATCH V2 4/8] mtip32xx: use blk_mq_queue_tag_inflight_iter Jianchao Wang
2019-03-25 5:38 ` [PATCH V2 5/8] nbd: " Jianchao Wang
2019-03-25 5:38 ` [PATCH V2 6/8] skd: " Jianchao Wang
2019-03-25 5:38 ` [PATCH V2 7/8] nvme: " Jianchao Wang
2019-03-25 13:49 ` Keith Busch [this message]
2019-03-26 1:17 ` jianchao.wang
2019-03-26 2:41 ` Ming Lei
2019-03-26 3:05 ` jianchao.wang
2019-03-26 23:57 ` Keith Busch
2019-03-27 2:03 ` jianchao.wang
2019-03-27 2:15 ` Keith Busch
2019-03-27 2:27 ` jianchao.wang
2019-03-27 2:33 ` Keith Busch
2019-03-27 2:45 ` jianchao.wang
2019-03-27 6:51 ` Keith Busch
2019-03-27 7:18 ` jianchao.wang
2019-03-25 5:38 ` [PATCH V2 8/8] blk-mq: remove blk_mq_tagset_busy_iter Jianchao Wang
2019-03-25 7:18 ` Hannes Reinecke
2019-03-25 7:37 ` jianchao.wang
2019-03-25 8:25 ` Hannes Reinecke
2019-03-25 9:12 ` jianchao.wang
2019-03-26 14:17 ` Jens Axboe
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