NAME

       fi_rxm - The RxM (RDM over MSG) Utility Provider

OVERVIEW

       The RxM provider (ofi_rxm) is an utility provider that supports RDM endpoint emulated over
       MSG endpoint of a core provider.

REQUIREMENTS

       RxM provider requires the core provider to support the following features:

       • MSG endpoints (FI_EP_MSG)

       • RMA read/write (FI_RMA)

       • FI_OPT_CM_DATA_SIZE of at least 24 bytes

SUPPORTED FEATURES

       The RxM provider currently supports FI_MSG, FI_TAGGED and FI_RMA capabilities.

       Endpoint types : The provider supports only FI_EP_RDM.

       Endpoint capabilities : The  following  data  transfer  interface  is  supported:  FI_MSG,
       FI_TAGGED, FI_RMA.

       Progress : The RxM provider supports FI_PROGRESS_AUTO.

       Addressing Formats : FI_SOCKADDR, FI_SOCKADDR_IN

       Memory  Region  :  FI_MR_VIRT_ADDR,  FI_MR_ALLOCATED, FI_MR_PROV_KEY MR mode bits would be
       required from the app in case the core provider requires it.

LIMITATIONS

       When using RxM provider, some limitations from the underlying MSG provider could also show
       up.   Please  refer  to  the  corresponding  MSG  provider  man  pages to find about those
       limitations.

   Unsupported features
       RxM provider does not support the following features:

       • op_flags: FI_FENCE.

       • FI_ATOMIC

       • Scalable endpoints

       • Shared contexts

       • FABRIC_DIRECT

       • FI_MR_SCALABLE

       • Authorization keys

       • Application error data buffers

       • Multicast

       • FI_ADDR_STR, FI_SYNC_ERR

       • Reporting unknown source addr data as part of completions

       • Triggered operations

   Auto progress
       When sending large messages, an app doing an sread or waiting on the  CQ  file  descriptor
       may  not get a completion when reading the CQ after being woken up from the wait.  The app
       has to do sread or wait on the file descriptor again.

RUNTIME PARAMETERS

       The ofi_rxm provider checks for the following environment variables.

       FI_OFI_RXM_BUFFER_SIZE : Defines the transmit buffer size / inject size.  Messages of size
       less  than  this  would  be  transmitted  via  an  eager protocol and those above would be
       transmitted via a rendezvous protocol.  Transmit data would be  copied  up  to  this  size
       (default: ~16k).

       FI_OFI_RXM_COMP_PER_PROGRESS  :  Defines  the  maximum  number  of MSG provider CQ entries
       (default: 1) that would be read per progress (RxM CQ read).

SEE ALSO

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

AUTHORS

       OpenFabrics.