1fi_mrail(7)                    Libfabric v1.7.0                    fi_mrail(7)
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NAME

6       fi_mrail - The Multi-Rail Utility Provider
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OVERVIEW

9       The  mrail provider (ofi_mrail) is an utility provider that layers over
10       an underlying provider to enable the  use  of  multiple  network  ports
11       (rails).  This increases the total available bandwidth of an underlying
12       proivder.  The current status of mrail provider is experimental  -  not
13       all libfabric features are supported and performance is not guaranteed.
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REQUIREMENTS

16   Requirements for underlying provider
17       mrail  provider requires the underlying provider to support the follow‐
18       ing capabilities / modes:
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20       · Buffered receive (FI_BUFFERED_RECV)
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22       · FI_SOURCE
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24       · FI_AV_TABLE
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26   Requirements for applications
27       Applications need to: * Support FI_MR_RAW MR mode bit to  make  use  of
28       FI_RMA capability.  * Set FI_OFI_MRAIL_ADDR_STRC env variable (see RUN‐
29       TIME PARAMETERS section below).
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SUPPORTED FEATURES

32       Endpoint types
33              The provider supports only FI_EP_RDM.
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35       Endpoint capabilities
36              The following data  transfer  interface  is  supported:  FI_MSG,
37              FI_TAGGED, FI_RMA.
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39       # LIMITATIONS
40              Limitations  of  the  underlying provider may show up as that of
41              mrail provider.
42       mrail provider doesn't allow pass-through of any mode bits to  the  un‐
43       derlying provider.
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45   Unsupported features
46       The  following are the major libfabric features that are not supported.
47       Any other feature not listed in "Supported features" can be assumed  as
48       unsupported.
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50       · FI_ATOMIC
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52       · Scalable endpoints
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54       · Shared contexts
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56       · FABRIC_DIRECT
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58       · Multicast
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60       · Triggered operations
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FUNCTIONALITY OVERVIEW

63       For  messages  (FI_MSG,  FI_TAGGED), the provider sends one message per
64       rail in a round-robin manner.  Ordering is guaranteed through  the  use
65       of  sequence  numbers.  For RMA, the data is striped equally across all
66       rails.
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RUNTIME PARAMETERS

69       The ofi_mrail provider checks for the following environment variables.
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71       FI_OFI_MRAIL_ADDR_STRC
72              Comma delimited list of individual rail addresses in FI_ADDR_STR
73              format.
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SEE ALSO

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

79       OpenFabrics.
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83Libfabric Programmer's Manual     2018-12-27                       fi_mrail(7)
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