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) Reliable 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 capabilities 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_FORMAT_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   routines.    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  targets  (FI_RMA_EVENT)  is  not  supported.   The DGRAM endpoint does not fully
       protect against resource overruns, 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 result 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.