Re: [PATCH 0/3] improve nvme quiesce time for large amount of namespaces

From: Christoph Hellwig <hch@lst.de>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: Chao Leng <lengchao@huawei.com>, Christoph Hellwig <hch@lst.de>,
	linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
	kbusch@kernel.org, axboe@kernel.dk
Subject: Re: [PATCH 0/3] improve nvme quiesce time for large amount of namespaces
Date: Tue, 2 Aug 2022 15:38:15 +0200	[thread overview]
Message-ID: <20220802133815.GA380@lst.de> (raw)
In-Reply-To: <fc7a303f-0921-f784-a559-f03511f2e4be@grimberg.me>

On Sun, Jul 31, 2022 at 01:23:36PM +0300, Sagi Grimberg wrote:
> But maybe we can avoid that, and because we allocate
> the connect_q ourselves, and fully know that it should
> not be apart of the tagset quiesce, perhaps we can introduce
> a new interface like:
> --
> static inline int nvme_ctrl_init_connect_q(struct nvme_ctrl *ctrl)
> {
> 	ctrl->connect_q = blk_mq_init_queue_self_quiesce(ctrl->tagset);
> 	if (IS_ERR(ctrl->connect_q))
> 		return PTR_ERR(ctrl->connect_q);
> 	return 0;
> }
> --
>
> And then blk_mq_quiesce_tagset can simply look into a per request-queue
> self_quiesce flag and skip as needed.

I'd just make that a queue flag set after allocation to keep the
interface simple, but otherwise this seems like the right thing
to do.