HP IO Accelerator for BladeSystem c-Class - Manual (Page 67)

NUMA configuration 67
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.
FIO_AFFINITY parameter
The FIO_AFFINITY parameter is a list of <affinity specification> triplets that specify the affinity
settings of all adapters in the system. Each item in the triplet is separated by a comma, and each triplet set
is separated by a semicolon.
Syntax
fio-config -p FIO_AFFINITY <affinity specification>[;<affinity
specification>...]
Where each <affinity specification> has the following syntax:
<fct number>,[g|n]<group or node number>[,<hex mask>]
If there is no g or n character before the group or node number, then the number is assumed to be a group
number.
The hex mask is optional. If it is not present, the mask is assumed to be 0xffffffffffffffff. Also, the
0x prefix is optional.
If the hex mask is a node mask, then the mask is relative to the node, not the group to which the node belongs.
Simple example
fio-config -p FIO_AFFINITY 4,n1,0xf;5,n0;7,g1;9,g2,0xff0
This command creates the following:
Device Node/Group Processor Affinity
fct4 node 1 Processors 0 to 3 in the node (mask 0xf)
fct5 node 0 All processors in the node (no hex mask)
fct7 group 1 All processors in the group (no hex mask)
fct9 group 2 Processors 4 to 11 in the group (mask 0xff0)