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PCI-MSI 49283113-edge
180:
PCI-MSI 49285129-edge
181:
PCI-MSI 49285161-edge
...
• To determine the current affinity of the interrupt <n> that is being used for a particular queue:
$ cat /proc/irq/<n>/smp_affinity
For example in the previous output, interrupt 114 is being used for receive queue 0 on the
enp1s0f0np0 interface. To determine its current affinity:
$ cat /proc/irq/114/smp_affinity
8
The output is a hexadecimal bitmask. In this example the output is 8 hex (i.e. bit 3 is set), and
so interrupt 114 is affinitized to CPU core 3.
• To set the current affinity of the interrupt <n>:
$ sudo echo <bitmask> > /proc/irq/<n>/smp_affinity
For example to affinitize interrupt 114 to CPU core 2, use a bitmask with value 4 (i.e. bit 2 is
set):
$ sudo echo 4 > /proc/irq/114/smp_affinity
The above techniques enable you to determine the associations between queues and CPU cores,
and to change them if necessary.
Set the CPU and Receive Queue for your Application
Now that you have determined the layout of your processor and receive queues, decide which
CPU and receive queue you want to use for your application. If necessary, revisit the previous
topics in this section.
Set the CPU for your application, and add ethtool rules to ensure that your application uses your
desired receive queue:
1. As root, install an ethtool rule to direct the traffic for your application to your desired receive
queue:
# ethtool -N <interface> flow-type tcp4|udp4|tcp6|udp6 dst-ip <ip_addr>
dst-port <port> queue <n>
For example if your application is using the enp1s0f0np0 interface, and will be receiving
UDP v4 traffic sent to port 1234 at address 192.168.10.200, then to use receive queue 3:
# ethtool -N enp1s0f0np0 flow-type udp4 dst-ip 192.168.10.200 dst-port
1234 queue 3
Added rule with ID 0
UG1523 (v1.0) October 18, 2022
Alveo X3522 User Guide
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