User Manual

Rev 2.2-1.0.1
Mellanox Technologies
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mode to that MR. The desired access is validated against its given permissions and upon
successful creation, the physical pages of the original MR are shared by the new MR.
Once the MR is shared, it can be used even if the original MR was destroyed.
The request to share the MR can be repeated multiple times and an arbitrary number of
Memory Regions can potentially share the same physical memory locations.
Usage:
• Uses the “handle” field that was returned from the ibv_exp_reg_mr as the mr_handle
• Supplies the desired “access mode” for that MR
• Supplies the address field which can be either NULL or any hint as the required output. The address and
its length are returned as part of the
ibv_mr struct.
To achieve high performance it is highly recommended to supply an address that is aligned as the origi-
nal memory region address. Generally, it may be an alignment to 4M address.
For further information on how to use the ibv_exp_reg_shared_mr verb, please refer to the
ibv_exp_reg_shared_mr man page and/or to the ibv_shared_mr sample program which demon-
strates a basic usage of this verb.
Further information on the
ibv_shared_mr sample program can be found in the ibv_shared_mr
man page.
4.13 XRC - eXtended Reliable Connected Transport Service for InfiniBand
XRC allows significant savings in the number of QPs and the associated memory resources
required to establish all to all process connectivity in large clusters.
It significantly improves the scalability of the solution for large clusters of multicore end-nodes
by reducing the required resources.
For further details, please refer to the "Annex A14 Supplement to InfiniBand Architecture Speci-
fication Volume 1.2.1"
A new API can be used by user space applications to work with the XRC transport. The legacy
API is currently supported in both binary and source modes, however it is deprecated.
Thus we
recommend using the new API.
The new verbs to be used are:
• ibv_open_xrcd/ibv_close_xrcd
• ibv_create_srq_ex
• ibv_get_srq_num
• ibv_create_qp_ex
• ibv_open_qp
Please use ibv_xsrq_pingpong for basic tests and code reference. For detailed information
regarding the various options for these verbs, please refer to their appropriate man pages.
4.14 Flow Steering
Flow Steering is applicable to the mlx4 driver only.
Flow steering is a new model which steers network flows based on flow specifications to specific
QPs. Those flows can be either unicast or multicast network flows. In order to maintain flexibil-