Introduction

In KVM4NFV project, we focus on the KVM hypervisor to enhance it for NFV, by looking at the following areas initially

  • Minimal Interrupt latency variation for data plane VNFs:
    • Minimal Timing Variation for Timing correctness of real-time VNFs
    • Minimal packet latency variation for data-plane VNFs

  • Inter-VM communication,

  • Fast live migration

Configuration of Cyclictest

Cyclictest measures Latency of response to a stimulus. Achieving low latency with the KVM4NFV project requires setting up a special test environment. This environment includes the BIOS settings, kernel configuration, kernel parameters and the run-time environment.

Pre-configuration activities

Intel POD1 is currently used as OPNFV-KVM4NFV test environment. The latest build packages are downloaded onto Intel Pod1-jump server from artifact repository. Yardstick running in a ubuntu docker container on Intel Pod1-jump server will trigger the cyclictest.

Running cyclictest through Yardstick will Configure the host(Pod1-node1), the guest, executes cyclictest on the guest.

The following scripts are used for configuring host and guest to create a special test environment and achieve low latency.

Note: host-setup0.sh, host-setup1.sh and host-run-qemu.sh are run on the host, followed by guest-setup0.sh and guest-setup1.sh scripts on the guest VM.

host-setup0.sh: Running this script will install the latest kernel rpm on host and will make necessary changes as following to create special test environment

  • Isolates CPUs from the general scheduler
  • Stops timer ticks on isolated CPUs whenever possible
  • Stops RCU callbacks on isolated CPUs
  • Enables intel iommu driver and disables DMA translation for devices
  • Sets HugeTLB pages to 1GB
  • Disables machine check
  • Disables clocksource verification at runtime

host-setup1.sh: Running this script will make the following test environment changes

  • Disabling watchdogs to reduce overhead
  • Disabling RT throttling
  • Reroute interrupts bound to isolated CPUs to CPU 0
  • Change the iptable so that we can ssh to the guest remotely
host-run-qemu.sh: Running this script will launch a guest vm on the host.
Note: download guest disk image from artifactory

guest-setup0.sh: Running this scrcipt on the guest vm will install the latest build kernel rpm, cyclictest and make the following configuration on guest vm.

  • Isolates CPUs from the general scheduler
  • Stops timer ticks on isolated CPUs whenever possible
  • Uses polling idle loop to improve performance
  • Disables clocksource verification at runtime

guest-setup1.sh: Running this script on guest vm will do the following configurations

  • Disable watchdogs to reduce overhead
  • Routes device interrupts to non-RT CPU
  • Disables RT throttling

Hardware configuration

Currently Intel POD1 is used as test environment for kvmfornfv to execute cyclictest. As part of this test environment Intel pod1-jump is configured as jenkins slave and all the latest build artifacts are downloaded on to it. Intel pod1-node1 is the host on which a guest vm will be launched as a part of running cylictest through yardstick.