Re: [PATCH rdma-next] RDMA/cma: Use ACK timeout for RoCE packetLifeTime

From: Dag Moxnes
Date: Tue Oct 29 2019 - 16:58:25 EST

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 CAâs 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@xxxxxxxxxx>
Change-Id: I200eda9d54829184e556c3c55d6a8869558d76b2
Please don't send Change-Id to the public lists. Run checkpatch before

Otherwise this seems reasonable to me..
Thanks for the review. Sorry about the Change-Id. I will send a v2 patch without it.