Resources (objects) operated on by Verbs
- Completion Queue (CQ):
- A queue (FIFO) which contains CQEs. Associated with a queue pair,
they are used to receive completion notifications and events.
- Completion Queue Entry (CQE):
- An entry in the CQ that describes the information about the completed
WR (status, size, etc.)
- Event Channel:
- Used to report communication events. Each event channel is mapped
to a file descriptor. The associated file descriptor can be used and
manipulated like any other fd to change its behavior. Users may make
the fd non-blocking, poll, or select the fd, etc.
- Memory Region (MR):
- A set of memory buffers that are already registered with access
permissions. These buffers require registration in order for the network
adapter to make use of them.
- Protection Domain (PD):
- Protection domains enable a client to associate multiple resources,
such as queue pairs, and memory regions, within a domain of trust.
The client can then grant access rights for sending/receiving data
within the protection domain to others that are on the RDMA fabric.
- Queue Pair (QP):
- Queue pairs (QPs) contain a send queue, for sending outbound messages
and requesting RDMA operations, and a receive queue for receiving
incoming messages or immediate data.
- Scatter /Gather Elements (SGE):
- An entry to a pointer to a full or a part of a local registered
memory block. The element holds the start address of the block, size,
and lkey (with its associated permissions).
- S/G Array:
- An array of S/G elements which exists in a Work Request (WR) that
according to the used opcode either collects data from multiple buffers
and sends them as a single stream or takes a single stream and breaks
it down to numerous buffers.
- Work Queue (WQ):
- Send Queue or Receive Queue.
- Work Queue Element (WQE):
- An element in a work queue.
- Work Request (WR):
- A request that was posted by a user to a work queue.