Re: [PATCH for-next] IB/cma: Introduce rdma_set_min_rnr_timer()

Haakon Bugge
2021-03-31T17:39:33Z

> On 31 Mar 2021, at 19:35, Jason Gunthorpe <jgg@nvidia.com> wrote:
>
> On Wed, Mar 31, 2021 at 05:09:27PM +0000, Parav Pandit wrote:
>>
>>
>>> From: Haakon Bugge <haakon.bugge@oracle.com>
>>> Sent: Wednesday, March 31, 2021 8:20 PM
>>>
>>>> On 31 Mar 2021, at 15:35, Jason Gunthorpe <jgg@nvidia.com> wrote:
>>>>
>>>> On Wed, Mar 31, 2021 at 01:34:06PM +0000, Haakon Bugge wrote:
>>>>
>>>>>> Actually I bet you could do this same thing entirely in userspace by
>>>>>> adjusting rdma_init_qp_attr() to copy the data that would be stored
>>>>>> in the cm_id.. ??
>>>>>
>>>>> This will definitely not solve the issue for kernel ULP, e.g., RDS.
>>>>
>>>> Sure, that makes sense to have some rdmacm api in-kernel only
>>>
>>> Let me send a v2 doing only that.
>>>
>>>>> Further, why do we have rdma_set_option() with option
>>> RDMA_OPTION_ID_ACK_TIMEOUT ?
>>>>
>>>> It may have been a mistake to do it like that
>>>
>> Timeout value goes in the CM request message so setting it through
>> the cm_id object was likely correct. This reflects into cm msg as
>> well as in the QP of the cm_id.
>
> Ah, yes if it goes in the wire in a CM message it has to go to the
> kernel.

But does it go on the wire? No. The RNR Retry timer is not part of the negotiation with the peer.

Håkon

>
> Jason