Binding NIC Interrupts to Cores

Purpose

Each CPU corresponds to a network interface card (NIC). Bind the cores of the CPU to the corresponding NIC by node.
The number of interrupts is as small as possible and all service cores run when the client is fully loaded and the CPU is fully occupied.
Use the same core binding script and execute the script on physical machines for the container in host network sharing mode and IPVLAN mode.

Procedure

Disable irqbalance.
Before binding cores to NICs, disable irqbalance.
1. Stop the irqbalance service.
  1
  systemctl stop irqbalance.service
  The preceding operation of stopping the irqbalance service will become invalid after the system is restarted. To permanently disable the irqbalance service, run the following command:
  
  1
  systemctl disable irqbalance.service
2. Check whether the irqbalance service is disabled.
  1
  systemctl status irqbalance.service

Bind NIC interrupts to cores. The bound cores are used to process NIC interrupts.

In the following example, bind the HTTP processes to four CPU cores to process short connections. To modify the core binding script, you only need to change the number of network port queues to be bound (cnt), the name of the network port to be bound (eth1), and the cores to be bound.

The core binding script is as follows:

#!/bin/bash 
# filename: irq_http_4core.sh
cnt=2
eth1=enp3s0
ethtool -L $eth1 combined $cnt
irq1=`cat /proc/interrupts| grep -E ${eth1} | head -1 | awk -F ':' '{print $1}'`
irq1=`echo $irq1`
i=0
while(( $i < 1))
do
        for cpunum in 2 3
        do
                echo $cpunum "->" $irq1
                echo  $cpunum > /proc/irq/$irq1/smp_affinity_list
                let "irq1++"
        done
        let "i++"
done

Table 1 describes the parameters and commands.

**Table 1** Parameter and command description
Parameter and Command	Description
cnt	Sets the number of network port queues. cnt is a variable, and 2 is the number of queues.
eth1	Sets the name of the network port used for communication. eth1 is a variable, and enp3s0 is the network port name.
irq1	Specifies the interrupt number of the network port eth1. irq1 is a variable.
cpunum	Specifies the core assigned to the network port eth1 for processing NIC interrupts. cpunum is a variable.
ethtool -L $eth1 combined $cnt	Sets the number of queues to the number of cores.
cat /proc/interrupts \| grep $eth1 \| awk -F ':' '{print $1}'	Queries the network port interrupt number.
echo $cpunum > /proc/irq/$irq/smp_affinity_list	Binds each interrupt to a core based on the interrupt number.

Parent topic: OS Tuning