fi_rxm(7) Libfabric Programmer's Manual
The RxM (RDM over MSG) Utility Provider
The RxM provider (ofi_rxm) is an utility provider that supports RDM endpoint emulated over MSG endpoint of a core provider.
RxM provider requires the core provider to support the following features:
MSG endpoints (FI_EP_MSG)
Shared receive contexts (FI_SHARED_CONTEXT)
RMA read/write (FI_RMA)
FI_OPT_CM_DATA_SIZE of atleast 24 bytes
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.
- The RxM provider supports only FI_PROGRESS_MANUAL for now.
- 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.
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.
RxM provider does not support the following features:
op_flags: FI_CLAIM, FI_PEEK, FI_FENCE.
Application error data buffers
Reporting unknown source addr data as part of completions
fi_cq_sread, fi_cq_sreadfrom and fi_cq_signal calls.
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.
RxM provider should work fine for client - server programs like fabtests. Support for MPI, SHMEM and other applications is work in progress.
Known failures in ofiwg/fabtests
- fi_poll -t queue
- fi_rma_bw -e rdm -o write
- fi_rma_bw -e rdm -o writedata
- fi_rdm_rma -o writedata
No runtime parameters are currently defined.