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From: Sagi Grimberg <sagi@grimberg.me>
To: Max Gurtovoy <mgurtovoy@nvidia.com>, Christoph Hellwig <hch@lst.de>
Cc: linux-nvme@lists.infradead.org, kbusch@kernel.org,
	chaitanyak@nvidia.com,  israelr@nvidia.com,
	mruijter@primelogic.nl, oren@nvidia.com, nitzanc@nvidia.com,
	Jason Gunthorpe <jgg@nvidia.com>
Subject: Re: [PATCH 2/2] nvmet-rdma: implement get_queue_size controller op
Date: Wed, 22 Sep 2021 12:18:15 +0300	[thread overview]
Message-ID: <6df58d37-0519-9e97-bae5-a529084c8341@grimberg.me> (raw)
In-Reply-To: <01762668-1572-9f37-73e8-714d4ff23323@nvidia.com>


>>> So for now, as mentioned, till we have some ib_ API, lets set it to 128.
>> Please just add the proper ib_ API, it should not be a whole lot of
>> work as we already do that calculation anyway for the R/W API setup.
> 
> We don't do this exact calculation since only the low level driver knows 
> that number of WQEs we need for some sophisticated WR.
> 
> The API we need is like ib_get_qp_limits when one provides some input on 
> the operations it will issue and will receive an output for it.
> 
> Then we need to divide it by some factor that will reflect the amount of 
> max WRs per NVMe request (e.g mem_reg + mem_invalidation + rdma_op + 
> pi_yes_no).
> 
> I spoke with Jason on that and we decided that it's not a trivial patch.

Can't you do this in rdmw_rw? all of the users of it will need the
exact same value right?

> is it necessary for this submission or can we live with 128 depth for 
> now ? with and without new ib_ API the queue depth will be in these sizes.

I am not sure I see the entire complexity. Even if this calc is not
accurate, you are already proposing to hard-code it to 128, so you
can do this to account for the boundaries there.

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  reply	other threads:[~2021-09-22  9:18 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-21 19:04 [PATCH v1 0/2] update RDMA controllers queue depth Max Gurtovoy
2021-09-21 19:04 ` [PATCH 1/2] nvmet: add get_queue_size op for controllers Max Gurtovoy
2021-09-21 19:20   ` Chaitanya Kulkarni
2021-09-21 22:47   ` Sagi Grimberg
2021-09-22  7:35     ` Max Gurtovoy
2021-09-21 19:04 ` [PATCH 2/2] nvmet-rdma: implement get_queue_size controller op Max Gurtovoy
2021-09-21 19:21   ` Chaitanya Kulkarni
2021-09-21 22:52   ` Sagi Grimberg
2021-09-22  7:44     ` Max Gurtovoy
2021-09-22  7:45       ` Christoph Hellwig
2021-09-22  8:10         ` Max Gurtovoy
2021-09-22  9:18           ` Sagi Grimberg [this message]
2021-09-22  9:35             ` Max Gurtovoy
2021-09-22 12:10             ` Jason Gunthorpe
2021-09-22 12:57               ` Max Gurtovoy
2021-09-22 13:31                 ` Jason Gunthorpe
2021-09-22 14:00                   ` Max Gurtovoy
2021-09-21 19:22 ` [PATCH v1 0/2] update RDMA controllers queue depth Chaitanya Kulkarni
2021-09-21 19:42   ` Mark Ruijter

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