NAME

fi_lpp - The LPP Fabric Provider

OVERVIEW

The LPP provider runs on FabreX PCIe networks. FabreX provides high performance RDMA capabilities which form the foundation of the LPP provider. Higher level primitives are implemented at the libfabric and LPP kernel module (KLPP) layers.

SUPPORTED FEATURES

The LPP provider supports a subset of the libfabric API. Key features include:

Endpoint types

LPP supports the FI_EP_RDM endpoint type with resource management.

Endpoint capabilities

LPP supports FI_MSG, FI_RMA, and FI_TAGGED message types.

Additional capabilities

LPP supports the additional features: FI_DIRECTED_RECV, FI_MULTI_RECV, FI_INJECT, FI_DELIVERY_COMPLETE

Progress

LPP currently supports only FI_PROGRESS_MANUAL. Therefore user applications are required to poll for progress.

LIMITATIONS

These features are unsupported: connection management, event queue, scalable endpoint, passive endpoint, shared receive context, atomics.

RUNTIME PARAMETERS

The LPP provider checks for the following environment variables -

FI_LPP_DISABLE_OSBYPASS

A bool which disables direct userspace writes when set. This can be used as a debugging aid, however it will degrade performance.

FI_LPP_MAX_WR_OSBYPASS_SIZE

Sets the maximum size for PIO when performing write RDMA transfers. Transfers at or below this size will use CPU copy, while transfers above it will use a DMA engine.

FI_LPP_MAX_RD_OSBYPASS_SIZE

Sets the maximum size for PIO when performing read RDMA transfers. Transfers at or below this size will use CPU copy, while transfers above it will use a DMA engine.

FI_LPP_CQ_OVERCOMMIT

A bool which allows operations to start that may overrun the CQ. Normally, when resource management is enabled, the LPP provider will attempt to throttle operations that might overrun the CQ. This parameter disables that behavior while leaving the remainder of the resource management features enabled.

FI_LPP_DOMAIN_CLEANUP

A bool which controls whether closing a domain with active resources will cause those resources to be automatically closed. If true (the default), the LPP provider will automatically close the resources.

FI_LPP_SYSTEM_MEMCPY

Use the memcpy implementation in the system libc rather than provider-specific memcpy.

SEE ALSO

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

AUTHORS

OpenFabrics.