NAME

       fi_efa - The Amazon Elastic Fabric Adapter (EFA) Provider

OVERVIEW

       The  EFA  provider supports the Elastic Fabric Adapter (EFA) device on Amazon EC2.  EFA provides reliable
       and unreliable datagram send/receive with direct hardware access from userspace (OS bypass).

SUPPORTED FEATURES

       The following features are supported:

       Endpoint types
              The provider supports endpoint type FI_EP_DGRAM, and FI_EP_RDM on a new Scalable (unordered) Reli‐
              able Datagram protocol (SRD).  SRD provides support for reliable datagrams and more complete error
              handling than typically seen with other Reliable Datagram (RD) implementations.  The EFA  provider
              provides  segmentation,  reassembly  of  out-of-order  packets to provide send-after-send ordering
              guarantees to applications via its FI_EP_RDM endpoint.

       RDM Endpoint capabilities
              The following  data  transfer  interfaces  are  supported  via  the  FI_EP_RDM  endpoint:  FI_MSG,
              FI_TAGGED, and FI_RMA.  FI_SEND, FI_RECV, FI_DIRECTED_RECV, FI_MULTI_RECV, and FI_SOURCE capabili‐
              ties  are  supported.   The endpoint provides send-after-send guarantees for data operations.  The
              FI_EP_RDM endpoint does not have a maximum message size.

       DGRAM Endpoint capabilities
              The DGRAM endpoint only supports FI_MSG capability with a maximum message size of the MTU  of  the
              underlying hardware (approximately 8 KiB).

       Address vectors
              The provider supports FI_AV_TABLE and FI_AV_MAP address vector types.  FI_EVENT is unsupported.

       Completion events
              The  provider  supports FI_CQ_FORMAT_CONTEXT, FI_CQ_FORMAT_MSG, and FI_CQ_FORMAT_DATA.  FI_CQ_FOR‐
              MAT_TAGGED is supported on the RDM endpoint.  Wait objects are not currently supported.

       Modes  The provider requires the use of FI_MSG_PREFIX when running over the DGRAM endpoint, and  requires
              FI_MR_LOCAL for all memory registrations on the DGRAM endpoint.

       Memory registration modes
              The  RDM  endpoint does not require memory registration and the FI_EP_DGRAM endpoint only supports
              FI_MR_LOCAL.

       Progress
              The RDM endpoint supports both FI_PROGRESS_AUTO and FI_PROGRESS_MANUAL, with the  default  set  to
              auto.   However,  receive side data buffers are not modified outside of completion processing rou‐
              tines.  The DGRAM endpoint only supports FI_PROGRESS_MANUAL.

       Threading
              The RDM endpoint supports FI_THREAD_SAFE, the DGRAM endpoint supports FI_THREAD_DOMAIN, i.e.   the
              provider is not thread safe when using the DGRAM endpoint.

LIMITATIONS

       The  provider  does not support FI_ATOMIC interfaces.  For RMA operations, completion events for RMA tar‐
       gets (FI_RMA_EVENT) is not supported.  The DGRAM endpoint does not fully protect against  resource  over‐
       runs, so resource management is disabled for this endpoint (FI_RM_DISABLED).

       No support for selective completions.

       No support for counters.

       No support for inject.

RUNTIME PARAMETERS

       FI_EFA_TX_SIZE
              Maximum  number  of  transmit operations before the provider returns -FI_EAGAIN.  For only the RDM
              endpoint, this parameter will cause transmit operations to be queued when this value is set higher
              than the default and the transmit queue is full.

       FI_EFA_RX_SIZE
              Maximum number of receive operations before the provider returns -FI_EAGAIN.

       FI_EFA_TX_IOV_LIMIT
              Maximum number of IOVs for a transmit operation.

       FI_EFA_RX_IOV_LIMIT
              Maximum number of IOVs for a receive operation.

RUNTIME PARAMETERS SPECIFIC TO RDM ENDPOINT

       These OFI runtime parameters apply only to the RDM endpoint.

       FI_EFA_RX_WINDOW_SIZE
              Maximum number of MTU-sized messages that can be in flight from any single  endpoint  as  part  of
              long message data transfer.

       FI_EFA_TX_QUEUE_SIZE
              Depth of transmit queue opened with the NIC.  This may not be set to a value greater than what the
              NIC supports.

       FI_EFA_RECVWIN_SIZE
              Size  of out of order reorder buffer (in messages).  Messages received out of this window will re‐
              sult in an error.

       FI_EFA_CQ_SIZE
              Size of any cq created, in number of entries.

       FI_EFA_MR_CACHE_ENABLE
              Enables using the mr cache and in-line registration instead of a bounce buffer  for  iov's  larger
              than max_memcpy_size.  Defaults to true.  When disabled, only uses a bounce buffer

       FI_EFA_MR_MAX_CACHED_COUNT
              Sets the maximum number of memory registrations that can be cached at any time.

       FI_EFA_MR_MAX_CACHED_SIZE
              Sets the maximum amount of memory that cached memory registrations can hold onto at any time.

       FI_EFA_MAX_MEMCPY_SIZE
              Threshold  size  switch  between  using memory copy into a pre-registered bounce buffer and memory
              registration on the user buffer.

       FI_EFA_MTU_SIZE
              Overrides the default MTU size of the device.

       FI_EFA_RX_COPY_UNEXP
              Enables the use of a separate pool of bounce-buffers  to  copy  unexpected  messages  out  of  the
              pre-posted receive buffers.

       FI_EFA_RX_COPY_OOO
              Enables  the  use of a separate pool of bounce-buffers to copy out-of-order RTS packets out of the
              pre-posted receive buffers.

       FI_EFA_MAX_TIMEOUT
              Maximum timeout (us) for backoff to a peer after a receiver not ready error.

       FI_EFA_TIMEOUT_INTERVAL
              Time interval (us) for the base timeout to use for exponential backoff to a peer after a  receiver
              not ready error.

       FI_EFA_ENABLE_SHM_TRANSFER
              Enable  SHM  provider  to provide the communication across all intra-node processes.  SHM transfer
              will be disabled in the case where ptrace protection is turned on.  You can turn it off to  enable
              shm transfer.

       FI_EFA_SHM_AV_SIZE
              Defines the maximum number of entries in SHM provider's address vector.

       FI_EFA_SHM_MAX_MEDIUM_SIZE
              Defines  the switch point between small/medium message and large message.  The message larger than
              this switch point will be transferred with large message protocol.

       FI_EFA_INTER_MAX_MEDIUM_MESSAGE_SIZE
              The maximum size for inter EFA messages to be sent by using  medium  message  protocol.   Messages
              which  can fit in one packet will be sent as eager message.  Messages whose sizes are smaller than
              this value will be sent using medium message protocol.  Other messages  will  be  sent  using  CTS
              based long message protocol.

SEE ALSO

       fabric(7), fi_provider(7), fi_getinfo(3)

AUTHORS

       OpenFabrics.

Libfabric Programmer's Manual                      2020-04-22                                          fi_efa(7)