SPEC Flag Description for Intel Xeon Phi BIOS Setup and Tuning

System and Other Tuning Information

Machine Configurations

BIOS settings

Simultaneous Multithreading

On 2nd generation Intel Xeon Phi processor and co-processors, Simultaneous Multithreading (SMT), permits 4 independent threads of execution on each core.

Cluster Mode:

This BIOS switch allows 5 options "All2All", "SNC-2", "SNC-4", "Hemisphere" and "Quadrant". Quadrant mode divides the chip into 4 virtual Quadrants. Quadrant mode can shorten the route length to memory, and that enable us to enlarge the bandwidth of memory.

Memory Mode

This BIOS switch allows 3 options "Cache", "Flat", and "Hybrid". Flat mode: the 16GB high bandwidth on-chip MCDRAM shares a single contiguous address space as the DRAM and is partitioned onto the second NUMA node. Cache mode: the MCDRAMs is used as the cache of DDR memory. Hybrid mode: a portion of the MCDRAM is used in flat mode, the rest is used as cache.

Turbo Mode

Enabling this switch allows the processor to provide more computing performance at short notice by increasing the frequency above nominal frequency.

Other Tuning Information

numactl [ --preferred node ] [ --membind nodes ]

Control NUMA policy for processes or shared memory.

--membind=nodes, -m nodes

Only allocate memory from nodes. Allocation will fail when there is not enough memory available on these nodes. Nodes may be specified as noted above

--preferred=node, -p node

Preferably allocate memory on node, but if memory cannot be allocated then fall back to other nodes. This option takes only a single node number. Relative notation may be used.