Configure windows RDMA Send operation IO timeout method

When use NDSPI on windows, send operation may return ND_IO_TIMEOUT; we want to know whether we can configure the timeout value; from find document,

  1. According to formula, enforced min timeout value is about 200ms, how could I know average timeout multiplier value from FW?
  2. I am not clear whether cm related(MaxCMRetries, RemoteCMResponseTimeout) or rdma related(RdmaDefaultAckTimeout, RdmaDefaultRetryCount) register key should I edit, does anyone know that?
  3. So I edit both of them

    Then I try to send 1000M data, cost about 2s, there is no timeout issue. Is it normal?


Thanks for your inquiry.
To answer your questions:

  1. Average timeout multiplier is 2, since it is the RTT.
  2. The relevant keys are the RDMA ones.
  3. Based on the information provided, we can’t know if this is normal behavior.
    For this, we will need more information.

If you’d like us to investigate, or if you have any further questions, please open a case at:, and it will be handled according to entitlement.

Best Regards,

Hello, thanks for your answer.
I am not clear about the last part of the QP timeout formula. If I set retry count as 1, QP timeout =268ms *1 *~2(2); ~2 is a minus value, is there anything wrong I understand? Send 1000M data is 325ms, how can I edit the registry to timeout this operation?