From: Sagi Grimberg <sagi@grimberg.me>
To: Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Keith Busch <kbusch@kernel.org>,
Christoph Hellwig <hch@lst.de>,
linux-nvme@lists.infradead.org,
James Smart <james.smart@broadcom.com>
Subject: Re: [PATCH RFC 0/3] blk-mq/nvme: use blk_mq_alloc_request() for NVMe's connect request
Date: Fri, 15 Nov 2019 14:38:44 -0800 [thread overview]
Message-ID: <8f4402a0-967d-f12d-2f1a-949e1dda017c@grimberg.me> (raw)
In-Reply-To: <20191115104238.15107-1-ming.lei@redhat.com>
> Hi,
Hey Ming,
> Use blk_mq_alloc_request() for allocating NVMe loop, fc, rdma and tcp's
> connect request, and selecting transport queue runtime for connect
> request.
>
> Then kill blk_mq_alloc_request_hctx().
Is it really so wrong to have an API to allocate a tag that belongs to
a specific queue? Why must the tags allocation always correlate to the
running cpu? Its true that NVMe is the only consumer of this at the
moment, but does this mean that the interface should be removed because
it has one (or rather four) consumer(s)?
I would instead suggest to simply remove the constraint that
blk_mq_alloc_request_hctx() will fail if the first cpu in the mask
is not on the cpu_online_mask.. The caller of this would know and
be able to handle it.
To me it feels like this approach is fundamentally wrong. IMO, having
the driver select a different queue than the tag naturally belongs to
feels like a backwards design.
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next prev parent reply other threads:[~2019-11-15 22:40 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 ` Sagi Grimberg [this message]
2019-11-16 7:17 ` [PATCH RFC 0/3] blk-mq/nvme: use blk_mq_alloc_request() for NVMe's connect request 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
2019-11-20 6:35 ` Ming Lei
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