RDMA/cma: Use ACK timeout for RoCE packetLifeTime (e1ee1e62) · Commits · 戴 / test

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. Link: https://lore.kernel.org/r/1572439440-17416-1-git-send-email-dag.moxnes@oracle.com Signed-off-by:

Dag Moxnes <dag.moxnes@oracle.com> Reviewed-by:

Jason Gunthorpe <jgg@mellanox.com> Signed-off-by:

Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/cma.c

+13 −2

Original line number	Diff line number	Diff line
		@@ -2504,7 +2504,9 @@ EXPORT_SYMBOL(rdma_set_service_type);
		* This function should be called before rdma_connect() on active side,
		* and on passive side before rdma_accept(). It is applicable to primary
		* path only. The timeout will affect the local side of the QP, it is not
		* negotiated with remote side and zero disables the timer.
		* negotiated with remote side and zero disables the timer. In case it is
		* set before rdma_resolve_route, the value will also be used to determine
		* PacketLifeTime for RoCE.
		*
		* Return: 0 for success
		*/
		@@ -2913,7 +2915,16 @@ static int cma_resolve_iboe_route(struct rdma_id_private *id_priv)
		route->path_rec->rate = iboe_get_rate(ndev);
		dev_put(ndev);
		route->path_rec->packet_life_time_selector = IB_SA_EQ;
		route->path_rec->packet_life_time = CMA_IBOE_PACKET_LIFETIME;
		/* In case ACK timeout is set, use this value to calculate
		* PacketLifeTime. 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.
		*/
		route->path_rec->packet_life_time = id_priv->timeout_set ?
		id_priv->timeout - 1 : CMA_IBOE_PACKET_LIFETIME;

		if (!route->path_rec->mtu) {
		ret = -EINVAL;
		goto err2;

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