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RDMA/cma: Use ACK timeout for RoCE packetLifeTime

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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>
This commit is contained in:
Dag Moxnes 2019-10-30 13:44:00 +01:00 committed by Jason Gunthorpe
parent 72b894b09a
commit e1ee1e62be
1 changed files with 13 additions and 2 deletions
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15
drivers/infiniband/core/cma.c
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@ -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;