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 IP VLAN mode.

Procedure

1. Disable irqbalance.

   1 2 3

   systemctl stop irqbalance.service systemctl disable irqbalance.service systemctl status irqbalance.service

2. 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 name of the network port to be bound (eth1) and the NIC queue depth (cnt).

   1. Create a script.

      1	vim irq_http_4core.sh

   2. Press i to enter the insert mode and add the following content to the file:

      #!/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	Specifies the number of network port queues. cnt is a variable, and 2 is the number of queues.
      eth1	Specifies 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	Specifies 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 $cpunum > /proc/irq/$irq1/smp_affinity_list	Binds each interrupt to a core based on the interrupt number.

   3. Press Esc, type :wq!, and press Enter to save the file and exit.
   4. Execute the script.

      1	sh irq_http_4core.sh