NAME

       fi_sockets - The Sockets Fabric Provider

OVERVIEW

       The  sockets  provider  is  a general purpose provider that can be used on any system that
       supports TCP sockets.  The provider is not intended to  provide  performance  improvements
       over  regular  TCP  sockets,  but  rather  to  allow  developers to write, test, and debug
       application code even on platforms that do not have high-performance fabric hardware.  The
       sockets provider supports all libfabric provider requirements and interfaces.

SUPPORTED FEATURES

       The  sockets  provider  supports  all  the  features  defined  for the libfabric API.  Key
       features include:

       Endpoint types : The provider supports  all  endpoint  types:  FI_EP_MSG,  FI_EP_RDM,  and
       FI_EP_DGRAM.

       Endpoint  capabilities  :  The  following  data  transfer interface is supported for a all
       endpoint types:  fi_msg.   Additionally,  these  interfaces  are  supported  for  reliable
       endpoints (FI_EP_MSG and FI_EP_RDM): fi_tagged, fi_atomic, and fi_rma.

       Modes  :  The  sockets  provider  supports  all operational modes including FI_CONTEXT and
       FI_MSG_PREFIX.

       Progress : Sockets provider supports both FI_PROGRESS_AUTO and FI_PROGRESS_MANUAL, with  a
       default  set  to  auto.   When progress is set to auto, a background thread runs to ensure
       that progress is made for asynchronous requests.

LIMITATIONS

       Sockets provider attempts to emulate the entire API set, including  all  defined  options.
       In  order  to  support  development on a wide range of systems, it is implemented over TCP
       sockets.  As a result, the performance numbers  are  lower  compared  to  other  providers
       implemented  over  high-speed  fabric,  and  lower  than  what  an  application  might see
       implementing to sockets directly.

       Does not support FI_ADDR_STR address format.

RUNTIME PARAMETERS

       The sockets provider checks for the following environment variables -

       FI_SOCKETS_PE_WAITTIME : An integer value that specifies how  many  milliseconds  to  spin
       while waiting for progress in FI_PROGRESS_AUTO mode.

       FI_SOCKETS_MAX_CONN_RETRY  :  An  integer  value  that  specifies  the  number  of  socket
       connection retries before reporting as failure.

       FI_SOCKETS_DEF_CONN_MAP_SZ : An integer to specify the default connection map size.

       FI_SOCKETS_DEF_AV_SZ : An integer to specify the default address vector size.

       FI_SOCKETS_DEF_CQ_SZ : An integer to specify the default completion queue size.

       FI_SOCKETS_DEF_EQ_SZ : An integer to specify the default event queue size.

       FI_SOCKETS_DGRAM_DROP_RATE : An integer value to specify the drop rate of dgram frame when
       endpoint is FI_EP_DGRAM.  This is for debugging purpose only.

       FI_SOCKETS_PE_AFFINITY  : If specified, progress thread is bound to the indicated range(s)
       of Linux virtual processor ID(s).  This option is currently not supported on  OS  X.   The
       usage is - id_start[-id_end[:stride]][,].

LARGE SCALE JOBS

       For large scale runs one can use these environment variables to set the default parameters
       e.g.  size of the address vector(AV), completion queue (CQ),  connection  map  etc.   that
       satisfies  the  requriment  of  the  particular benchmark.  The recommended parameters for
       large    scale    runs    are    FI_SOCKETS_MAX_CONN_RETRY,    FI_SOCKETS_DEF_CONN_MAP_SZ,
       FI_SOCKETS_DEF_AV_SZ, FI_SOCKETS_DEF_CQ_SZ, FI_SOCKETS_DEF_EQ_SZ.

SEE ALSO

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

AUTHORS

       OpenFabrics.