HP MSR Encryption Accelerators - Manual (Page 57)

NUMA configuration 57
NUMA configuration
Introduction to NUMA architecture
Servers with NUMA (Non-Uniform Memory Access) architecture require special installation instructions in
order to maximize IO Accelerator device performance. These servers include the HP DL580 and the HP
DL980 server.
On servers with NUMA architecture, during system boot, the BIOS on some systems will not distribute PCIe
slots evenly among the NUMA nodes. Each NUMA node contains multiple CPUs. This imbalanced
distribution means that, during high workloads, half or more of the CPUs will remain idle while the rest are
100% utilized. To prevent this imbalance, you must manually assign IO Accelerator devices equally among
the available NUMA nodes.
Configuring the IO Accelerator devices for servers with NUMA architecture requires the use of the
FIO_AFFINTIY parameter with the fio-config utility.
NUMA node override parameter
The numa_node_override parameter is a list of <affinity specification> couplets that specify the
affinity settings of all devices in the system. Each item in the couplet is separated by a colon, and each couplet
set is separated by a comma.
Syntax
numa_node_override=<affinity specification>[,<affinity specification>...]
Where each <affinity specification> has the following syntax:
<fct-number>:<node-number>
Simple example
numa_node_override=fct4:1,fct5:0,fct7:2,fct9:3
has the effect of creating:
Device Node/group Process or affinity
fct4
node 1 all processors in node 1
fct5 node 0 all processors in node 0
fct7 node 2 all processors in node 2
fct9 node 3 all processors in node 3
Advanced configuration example
This example server has four NUMA nodes with eight hyper-threaded cores per node (16 logical processors
per node, a total of 64 logical processors in the system). This system also uses the expansion configuration
and has 11 PCIe expansion slots. During system boot, the system BIOS assigns PCIe slots 1-6 to NUMA node
2 and PCIe slots 7-11 to NUMA node 0. NUMA nodes 1 and 3 have no assigned PCIe slots. This