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From: Christoph Hellwig <hch@lst.de>
To: Sagi Grimberg <sagi@grimberg.me>, Jens Axboe <axboe@kernel.dk>
Cc: linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
	linux-rdma@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Keith Busch <keith.busch@intel.com>
Subject: Re: [PATCH RFC 4/4] nvme-multipath: disable polling for underlying namespace request queue
Date: Wed, 12 Dec 2018 08:11:40 +0100	[thread overview]
Message-ID: <20181212071140.GD28461@lst.de> (raw)
In-Reply-To: <20181211233652.9705-5-sagi@grimberg.me>

[adding Jens]

> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -1547,6 +1547,8 @@ static void __nvme_revalidate_disk(struct gendisk *disk, struct nvme_id_ns *id)
>  	if (ns->head->disk) {
>  		nvme_update_disk_info(ns->head->disk, ns, id);
>  		blk_queue_stack_limits(ns->head->disk->queue, ns->queue);
> +		/* XXX: multipath device does not support polling for now... */
> +		blk_queue_flag_clear(QUEUE_FLAG_POLL, ns->queue);

I'd drop the XXX.  But I think we actually have a block layer problem
here.  Currently stacking devices will just pass through REQ_HIPRI,
despite none of them supporting any polling for it.

So we need to make sure in the block layer or I/O submitter that
REQ_HIPRI is only set if QUEUE_FLAG_POLL is supported.  I think it would
also help if we rename it to REQ_POLL to make this more obvious.


WARNING: multiple messages have this Message-ID (diff)
From: hch@lst.de (Christoph Hellwig)
Subject: [PATCH RFC 4/4] nvme-multipath: disable polling for underlying namespace request queue
Date: Wed, 12 Dec 2018 08:11:40 +0100	[thread overview]
Message-ID: <20181212071140.GD28461@lst.de> (raw)
In-Reply-To: <20181211233652.9705-5-sagi@grimberg.me>

[adding Jens]

> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -1547,6 +1547,8 @@ static void __nvme_revalidate_disk(struct gendisk *disk, struct nvme_id_ns *id)
>  	if (ns->head->disk) {
>  		nvme_update_disk_info(ns->head->disk, ns, id);
>  		blk_queue_stack_limits(ns->head->disk->queue, ns->queue);
> +		/* XXX: multipath device does not support polling for now... */
> +		blk_queue_flag_clear(QUEUE_FLAG_POLL, ns->queue);

I'd drop the XXX.  But I think we actually have a block layer problem
here.  Currently stacking devices will just pass through REQ_HIPRI,
despite none of them supporting any polling for it.

So we need to make sure in the block layer or I/O submitter that
REQ_HIPRI is only set if QUEUE_FLAG_POLL is supported.  I think it would
also help if we rename it to REQ_POLL to make this more obvious.

  reply	other threads:[~2018-12-12  7:11 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-11 23:36 [PATCH RFC 0/4] restore polling to nvme-rdma Sagi Grimberg
2018-12-11 23:36 ` Sagi Grimberg
2018-12-11 23:36 ` [PATCH RFC 1/4] nvme-fabrics: allow user to pass in nr_poll_queues Sagi Grimberg
2018-12-11 23:36   ` Sagi Grimberg
2018-12-11 23:36 ` [PATCH RFC 2/4] rdma: introduce ib_change_cq_ctx Sagi Grimberg
2018-12-11 23:36   ` Sagi Grimberg
2018-12-11 23:36 ` [PATCH RFC 3/4] nvme-rdma: implement polling queue map Sagi Grimberg
2018-12-11 23:36   ` Sagi Grimberg
2018-12-11 23:36 ` [PATCH RFC 4/4] nvme-multipath: disable polling for underlying namespace request queue Sagi Grimberg
2018-12-11 23:36   ` Sagi Grimberg
2018-12-12  7:11   ` Christoph Hellwig [this message]
2018-12-12  7:11     ` Christoph Hellwig
2018-12-12  7:19     ` Sagi Grimberg
2018-12-12  7:19       ` Sagi Grimberg
2018-12-12  7:21       ` Christoph Hellwig
2018-12-12  7:21         ` Christoph Hellwig
2018-12-12  7:29         ` Sagi Grimberg
2018-12-12  7:29           ` Sagi Grimberg
2018-12-12  7:37           ` Christoph Hellwig
2018-12-12  7:37             ` Christoph Hellwig
2018-12-11 23:36 ` [PATCH RFC nvme-cli 5/4] fabrics: pass in number of polling queues Sagi Grimberg
2018-12-11 23:36   ` Sagi Grimberg
2018-12-12  0:27   ` Sagi Grimberg
2018-12-12  0:27     ` Sagi Grimberg
2018-12-12  7:07 ` [PATCH RFC 0/4] restore polling to nvme-rdma Christoph Hellwig
2018-12-12  7:07   ` Christoph Hellwig
2018-12-12  7:16   ` Sagi Grimberg
2018-12-12  7:16     ` Sagi Grimberg
2018-12-12  8:09     ` Christoph Hellwig
2018-12-12  8:09       ` Christoph Hellwig
2018-12-12  8:53       ` Sagi Grimberg
2018-12-12  8:53         ` Sagi Grimberg
2018-12-12 14:05         ` Christoph Hellwig
2018-12-12 14:05           ` Christoph Hellwig
2018-12-12 18:23           ` Sagi Grimberg
2018-12-12 18:23             ` Sagi Grimberg
2018-12-12 16:37 ` Steve Wise
2018-12-12 16:37   ` Steve Wise
2018-12-12 18:05   ` Sagi Grimberg
2018-12-12 18:05     ` Sagi Grimberg
2018-12-12 18:10     ` Steve Wise
2018-12-12 18:10       ` Steve Wise

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