From: James Smart <james.smart@broadcom.com>
To: Sagi Grimberg <sagi@grimberg.me>, Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Keith Busch <kbusch@kernel.org>,
linux-nvme@lists.infradead.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH RFC 0/3] blk-mq/nvme: use blk_mq_alloc_request() for NVMe's connect request
Date: Tue, 19 Nov 2019 09:56:45 -0800 [thread overview]
Message-ID: <fda43a50-a484-dde7-84a1-94ccf9346bdd@broadcom.com> (raw)
In-Reply-To: <016afdbc-9c63-4193-e64b-aad91ba5fcc1@grimberg.me>
On 11/18/2019 4:05 PM, Sagi Grimberg wrote:
>
> This is a much simpler fix that does not create this churn local to
> every driver. Also, I don't like the assumptions about tag reservations
> that the drivers is taking locally (that the connect will have tag 0
> for example). All this makes this look like a hack.
Agree with Sagi on this last statement. When I reviewed the patch, it
was very non-intuitive. Why dependency on tag 0, why a queue number
squirrelled away on this one request only. Why change the initialization
(queue pointer) on this one specific request from its hctx and so on.
For someone without the history, ugly.
>
> I'm starting to think we maybe need to get the connect out of the block
> layer execution if its such a big problem... Its a real shame if that is
> the case...
Yep. This is starting to be another case of perhaps I should be changing
nvme-fc's blk-mq hctx to nvme queue relationship in a different manner.
I'm having a very hard time with all the queue resources today's policy
is wasting on targets.
-- james
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next prev parent reply other threads:[~2019-11-19 17:56 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-15 10:42 [PATCH RFC 0/3] blk-mq/nvme: use blk_mq_alloc_request() for NVMe's connect request Ming Lei
2019-11-15 10:42 ` [PATCH RFC 1/3] block: reuse one scheduler/flush field for private request's data Ming Lei
2019-11-15 10:42 ` [PATCH RFC 2/3] nvme: don't use blk_mq_alloc_request_hctx() for allocating connect request Ming Lei
2019-11-15 10:42 ` [PATCH RFC 3/3] blk-mq: kill blk_mq_alloc_request_hctx() Ming Lei
2019-11-15 22:38 ` [PATCH RFC 0/3] blk-mq/nvme: use blk_mq_alloc_request() for NVMe's connect request Sagi Grimberg
2019-11-16 7:17 ` Ming Lei
2019-11-17 1:24 ` Bart Van Assche
2019-11-17 4:12 ` Ming Lei
2019-11-18 23:27 ` Bart Van Assche
2019-11-19 0:05 ` Sagi Grimberg
2019-11-19 0:34 ` Keith Busch
2019-11-19 1:43 ` Sagi Grimberg
2019-11-19 2:38 ` Ming Lei
2019-11-19 2:33 ` Ming Lei
2019-11-19 17:56 ` James Smart [this message]
2019-11-20 6:35 ` Ming Lei
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