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Subject: Re: [PATCH rdma-next] RDMA/cma: Use ACK timeout for RoCE
 packetLifeTime
To:     Jason Gunthorpe <jgg@ziepe.ca>
Cc:     dledford@redhat.com, leon@kernel.org, parav@mellanox.com,
        linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1572003721-26368-1-git-send-email-dag.moxnes@oracle.com>
 <20191029195101.GA1654@ziepe.ca>
From:   Dag Moxnes <dag.moxnes@oracle.com>
Message-ID: <3ce751b9-7f74-e197-f15c-cf76ffd1dd71@oracle.com>
Date:   Tue, 29 Oct 2019 21:58:04 +0100
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Hi Jason,

Den 29.10.2019 20:51, skrev Jason Gunthorpe:
> On Fri, Oct 25, 2019 at 01:42:01PM +0200, Dag Moxnes wrote:
>> The cma is currently using a hard-coded value, CMA_IBOE_PACKET_LIFETIME,
>> for the PacketLifeTime, as it can not be determined from the network.
>> This value might not be optimal for all networks.
>>
>> The cma module supports the function rdma_set_ack_timeout to set the
>> ACK timeout for a QP associated with a connection. As per IBTA 12.7.34
>> local ACK timeout = (2 * PacketLifeTime + Local CA’s ACK delay).
>> Assuming a negligible local ACK delay, we can use
>> PacketLifeTime = local ACK timeout/2
>> as a reasonable approximation for RoCE networks.
>>
>> Signed-off-by: Dag Moxnes <dag.moxnes@oracle.com>
>> Change-Id: I200eda9d54829184e556c3c55d6a8869558d76b2
> Please don't send Change-Id to the public lists. Run checkpatch before
> sending.
>
> Otherwise this seems reasonable to me..
Thanks for the review. Sorry about the Change-Id. I will send a v2 patch 
without it.

Regards,
-Dag
>
> Jason