Re: [PATCH v1 0/2] update RDMA controllers queue depth

[Chaitanya Kulkarni <chaitanyak@nvidia.com>]

Mark,

On 9/21/2021 12:04 PM, Max Gurtovoy wrote:
> Hi all,
> This series is solving the issue that was introduced by Mark Ruijter
> while testing SPDK initiators on Vmware-7.x while connecting to Linux
> RDMA target running on NVIDIA's ConnectX-6 Mellanox Technologies
> adapter. During connection establishment, the NVMf target controller
> expose a 1024 queue depth capability but wasn't able to satisfy this
> depth in reality. The reason for that is that the NVMf driver didn't
> take the underlying HW capabilities into consideration. For now, limit
> the RDMA queue depth to a value of 128 (that is the default and works
> for all the RDMA controllers probably). For that, introduce a new
> controller operation to return the possible queue size for a given HW.
> Other transport will continue with thier old behaviour.
> 
> In the future, in order to increase this size, we'll need to create a
> special RDMA API to calculate a possible queue depth for ULPs. As we
> know, the RDMA IO operations sometimes are built from multiple WRs (such
> as memory registrations and invalidations) that the ULP driver should
> take this into consideration during device discovery and queue depth
> calculations.
> 
> Max Gurtovoy (2):
>    nvmet: add get_queue_size op for controllers
>    nvmet-rdma: implement get_queue_size controller op
> 
>   drivers/nvme/target/core.c  | 8 +++++---
>   drivers/nvme/target/nvmet.h | 1 +
>   drivers/nvme/target/rdma.c  | 8 ++++++++
>   3 files changed, 14 insertions(+), 3 deletions(-)
> 

It will be great if you can provide tested by tag.

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