User Manual

Rev 2.2-1.0.1
Mellanox Technologies
145
 To enable FCA in the shmemrun command line, add the following:
-mca scoll_fca_enable=1
-mca scoll_fca_enable_np 0
 To disable FCA:
-mca scoll_fca_enable 0 -mca coll_fca_enable 0
For more details on FCA installation and configuration, please refer to the FCA User Manual
found in the Mellanox website.
5.2.3 Running ScalableSHMEM with MXM
MellanoX Messaging (MXM) library provides enhancements to parallel communication libraries
by fully utilizing the underlying networking infrastructure provided by Mellanox HCA/switch
hardware. This includes a variety of enhancements that take advantage of Mellanox networking
hardware including:
• Multiple transport support including RC, XRC and UD
• Proper management of HCA resources and memory structures
• Efficient memory registration
• One-sided communication semantics
• Connection management
• Receive side tag matching
• Intra-node shared memory communication
These enhancements significantly increase the scalability and performance of message com-
muni-cations in the network, alleviating bottlenecks within the parallel communication libraries
5.2.4 Running SHMEM with Contiguous Pages
Contiguous Pages improves performance by allocating user memory regions over contiguous
pages. It enables a user application to ask low level drivers to allocate contiguous memory for it
as part of
ibv_reg_mr.
 To activate MLNX_OFED 2.0 and the contiguous pages allocator with SHMEM:
Run the following argument to enable compound pages with SHMEM:
% /opt/mellanox/openshmem/2.1/bin/shmemrun -mca shmalloc_use_hugepages 5
If using compound pages is not possible, then the user will fall back to regular hugepages
mechanism.
 To force use of compound pages allocator
Run the following command:
% /opt/mellanox/openshmem/2.1/bin/shmemrun -mca shmalloc_use_hugepages 5 -x
MR_FORCE_CONTIG_PAGES=1
For further information on the Contiguous Pages, please refer to Section 4.11, “Contiguous
Pages”, on page 105.