14.3. Sample deployment and testing scenario

The following example procedure uses a simple single-node deployment to test that the environment variables and other supporting configuration is set up correctly. Actual performance results might vary, depending on the number of nodes and instances that you deploy in your cloud.


  1. Create the compute-real-time.yaml file with the following parameters:

        IsolCpusList: "1"
        NovaComputeCpuDedicatedSet: "1"
        NovaComputeCpuSharedSet: "0"
        KernelArgs: "default_hugepagesz=1G hugepagesz=1G hugepages=16"
        NovaComputeDisableIrqBalance: true
  2. Create a new rt_roles_data.yaml file with the ComputeRealTime role:

    $ openstack overcloud roles generate \
     -o ~/rt_roles_data.yaml Controller ComputeRealTime
  3. Add compute-real-time.yaml and rt_roles_data.yaml to the stack with your other environment files and deploy the overcloud:

    (undercloud)$ openstack overcloud deploy --templates \
      -r /home/stack/rt_roles_data.yaml \
      -e [your environment files] \
      -e /home/stack/templates/compute-real-time.yaml

    This command deploys one Controller node and one Real-time Compute node.

  4. Log into the Real-time Compute node and check the following parameters:

    [root@overcloud-computerealtime-0 ~]# uname -a
    Linux overcloud-computerealtime-0 4.18.0-80.7.1.rt9.153.el8_0.x86_64 #1 SMP PREEMPT RT Wed Dec 13 13:37:53 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
    [root@overcloud-computerealtime-0 ~]# cat /proc/cmdline
    BOOT_IMAGE=/boot/vmlinuz-4.18.0-80.7.1.rt9.153.el8_0.x86_64 root=UUID=45ae42d0-58e7-44fe-b5b1-993fe97b760f ro console=tty0 crashkernel=auto console=ttyS0,115200 default_hugepagesz=1G hugepagesz=1G hugepages=16
    [root@overcloud-computerealtime-0 ~]# tuned-adm active
    Current active profile: realtime-virtual-host
    [root@overcloud-computerealtime-0 ~]# grep ^isolated_cores /etc/tuned/realtime-virtual-host-variables.conf
    [root@overcloud-computerealtime-0 ~]# cat /usr/lib/tuned/realtime-virtual-host/lapic_timer_adv_ns
    4000 # The returned value must not be 0
    [root@overcloud-computerealtime-0 ~]# cat /sys/module/kvm/parameters/lapic_timer_advance_ns
    4000 # The returned value must not be 0
    # To validate hugepages at a host level:
    [root@overcloud-computerealtime-0 ~]# cat /proc/meminfo | grep -E HugePages_Total|Hugepagesize
    HugePages_Total:      64
    Hugepagesize:    1048576 kB
    # To validate hugepages on a per NUMA level (below example is a two NUMA compute host):
    [root@overcloud-computerealtime-0 ~]# cat /sys/devices/system/node/node0/hugepages/hugepages-1048576kB/nr_hugepages
    [root@overcloud-computerealtime-0 ~]# cat /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages
    [root@overcloud-computerealtime-0 ~]# crudini --get /var/lib/config-data/puppet-generated/nova_libvirt/etc/nova/nova.conf compute cpu_dedicated_set
    [root@overcloud-computerealtime-0 ~]# crudini --get /var/lib/config-data/puppet-generated/nova_libvirt/etc/nova/nova.conf compute cpu_shared_set
    [root@overcloud-computerealtime-0 ~]# systemctl status irqbalance
    ● irqbalance.service - irqbalance daemon
       Loaded: loaded (/usr/lib/systemd/system/irqbalance.service; enabled; vendor preset: enabled)
       Active: inactive (dead) since Tue 2021-03-30 13:36:31 UTC; 2s ago