fi_direct(7) @VERSION@ fi_direct(7)NAMEfi_direct - Direct fabric provider access
SYNOPSIS-DFABRIC_DIRECT
#define FABRIC_DIRECT
Fabric direct provides a mechanism for applications to compile against
a specific fabric providers without going through the libfabric frame‐
work or function vector tables. This allows for extreme optimization
via function inlining at the cost of supporting multiple providers or
different versions of the same provider.
DESCRIPTION
The use of fabric direct is intended only for applications that require
the absolute minimum software latency, and are willing to re-compile
for specific fabric hardware. Providers that support fabric direct
implement their own versions of the static inline calls which are
define in the libfabric header files, define selected enum values, and
provide defines for compile-time optimizations. Applications can then
code against the standard libfabric calls, but link directly against
the provider calls by defining FABRIC_DIRECT as part of their build.
In general, the use of fabric direct does not require application
source code changes, and, instead, is limited to the build process.
Providers supporting fabric direct must install 'direct' versions of
all libfabric header files. For convenience, the libfabric sources
contain sample header files that may be modified by a provider. The
'direct' header file names have 'fi_direct' as their prefix:
fi_direct.h, fi_direct_endpoint.h, etc.
Direct providers are prohibited from overriding or modifying existing
data structures. However, provider specific extensions are still
available. In addition to provider direct function calls to provider
code, a fabric direct provider may define zero of more of the following
capability definitions. Applications can check for these capabilities
in order to optimize code paths at compile time, versus relying on
run-time checks.
CAPABILITY DEFINITIONS
In order that application code may be optimized during compile time,
direct providers must provide definitions for various capabilities and
modes, if those capabilities are supported. The following #define val‐
ues may be used by an application to test for provider support of sup‐
ported features.
FI_DIRECT_CONTEXT : The provider sets FI_CONTEXT or FI_CONTEXT2 for
fi_info:mode. See fi_getinfo for additional details. When
FI_DIRECT_CONTEXT is defined, applications should use struct fi_context
in their definitions, even if FI_CONTEXT2 is set.
FI_DIRECT_LOCAL_MR : The provider sets FI_LOCAL_MR for fi_info:mode.
See fi_getinfo for additional details.
SEE ALSOfi_getinfo(3), fi_endpoint(3), fi_domain(3)AUTHORS
OpenFabrics.
Libfabric Programmer's Manual 2017-04-13 fi_direct(7)
