QP State before Any Messages Are Transferred
Connection Established and QPs Fully Configured
This discussion assumes that the following series of actions have already been accomplished:
The local HCA RC QP was created (see “QP Creation” on page 236) and connected to a local HCA port that it will use to send and receive messages between itself and a RC QP in a remote CA (see “RC/UC Connection Establishment” on page 186).
The CMs associated with the HCA and the remote CA have exchanged REQ, REP, and RTU messages.
Both QPs are fully configured and in the fully operational RTS state (see “Ready to Send State” on page 247).
Current QP State
The two QPs have been configured with the information detailed in Table 17-2 on this page.
| Operational Parameter | Description |
|---|---|
| QP Type | RC. |
| QPN | 24-bit QPN assigned to this QP. |
| CQ(s) | One or two CQs have been created and assigned to the QP's SQ and RQ. The same CQ may be used by both queues or a separate CQ may have been assigned to each of them. The CQ(s) are currently empty (i.e., they contain no CQEs). |
| SQ and RQ | The QP's SQ and RQ have been created and are currently empty (i.e., they contain no WQEs). |
| Maximum Number of Scatter/Gather Elements | The SQ and RQ have been configured with the maximum number of local memory buffers that will be specified in any WR's Scatter or Gather Buffer List. |
| SQ Completion Signaling Type | The SQ Logic has been programmed to create a CQE on the SCQ under one of the following circumstances:
|
| Protection Domain (PD) | The QP has been assigned to a PD. The QP logic is only permitted to access a local memory region or window that has been assigned to the same PD. |
| Current QP State | Both QPs are in the fully operational RTS state. |
| Primary P_Key Index |
|
| SQ's Start PSN | This is the Start PSN assigned to this QP's SQ Logic by software. It is inserted into the BTH:PSN field in the first request packet generated by the SQ Logic. The other QP's RQ Start ePSN is set to the same value (the value was supplied by the CM in the connection REQ message). |
| RQ Start ePSN | RQ Logic 's Start ePSN is set to the SQ Start PSN assigned to the remote QP's SQ Logic. It was returned in the REP message during connection establishment. RQ Logic uses ePSN to verify that the next request packet received has the next expected PSN. |
| Primary Physical Port Number | Physical CA port the QP will use to send and receive messages. Called the primary port to differentiate it from the Alternate Path Physical Port. |
| Destination QP Number (QPN) | Inserted in the BTH:DestQP field in outbound request packets. Identifies the target QP to whom the request packet is to be delivered. It was returned in the REP message during connection establishment. |
| DLID |
|
| Send GRH Flag (and global routing information if the destination port is in a different subnet) |
|
| Enable or disable incoming RDMA and Atomic operations |
|
| Number of RDMA Reads & Atomic operations outstanding at any time | Depth of remote QP's special queue for receiving inbound RDMA Read/Atomic operations from this QP's SQ Logic. It was returned in the REP message during connection establishment. |
| Queue depth for inbound RDMA Read/Atomic operations | Depth of the special queue in this QP's RQ Logic into which inbound RDMA Read and Atomic operation requests are received. |
| Service Level (SL) | 4-bits. Represents the desired QoS within this subnet for message request packets generated by this QP's SQ Logic. Inserted in the LRH:SL field of each request packet. |
| Path MTU (PMTU) | See “Maximum Data Payload Size” on page 42. |
| Maximum Static Rate | See “Packet Injection Delay” on page 43. |
| Minimum RNR Nak Timer field value | If an inbound Send or RDMA Write With Immediate message arrives when no WQEs are posted to this QP's RQ, the RQ Logic responds with an RNR Nak. This is the value that is placed in the Nak packet's RNR Nak Timer Field. The packet sender must wait at least this amount of time before attempting to resend the request packet again. |
| Local ACK Timeout | Defines the amount of time the QP's SQ Logic will wait for a response before it retries the transmission of the corresponding request packet (see “SQ Logic's Transport Timer” on page 381). |
| Retry Count | See “Ack Timeout and Missing Packet(s) Retry Counter” on page 44. |
| RNR Retry Count | See “Receiver Not Ready (RNR) Retry Count” on page 45. It was returned in the REP message during connection establishment. Note that a count of 7d (111b) indicates infinite retries. |
| Source Path Bits | See “Source Port's LID Address” on page 45. |
| Alternate Path Address Information | Applicable only if Automatic Path Migration is supported; for detail, see “Automatic Path Migration” on page 575, “LAP (Load Alternate Path) MAD” on page 1104, and “APR (Alternate Path Response) MAD” on page 1107.
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| Path Migration State | Valid only if this CA supports Automatic Path Migration; for detail, see “Automatic Path Migration” on page 575. Valid states are:
|