Chapter 11. Enabling RT-KVM for NFV Workloads

Building the real-time image

1. Install the libguestfs-tools package on the undercloud to get the virt-customize tool:

   (undercloud) [stack@undercloud-0 ~]$ sudo dnf install libguestfs-tools

   Important

   If you install the libguestfs-tools package on the undercloud, disable iscsid.socket to avoid port conflicts with the tripleo_iscsid service on the undercloud:

   $ sudo systemctl disable --now iscsid.socket

2. Extract the images:

   (undercloud) [stack@undercloud-0 ~]$ tar -xf /usr/share/rhosp-director-images/overcloud-full.tar
   (undercloud) [stack@undercloud-0 ~]$ tar -xf /usr/share/rhosp-director-images/ironic-python-agent.tar

3. Copy the default image:

   (undercloud) [stack@undercloud-0 ~]$ cp overcloud-hardened-uefi-full.qcow2 overcloud-realtime-compute.qcow2

4. Register your image to enable Red Hat repositories relevant to your customizations. Replace [username] and [password] with valid credentials in the following example.

   virt-customize -a overcloud-realtime-compute.qcow2 --run-command \
   'subscription-manager register --username=[username] --password=[password]' \
   subscription-manager release --set 8.4

   Note

   For security, you can remove credentials from the history file if they are used on the command prompt. You can delete individual lines in history using the history -d command followed by the line number.

5. Find a list of pool IDs from your account’s subscriptions, and attach the appropriate pool ID to your image.

   sudo subscription-manager list --all --available | less
   ...
   virt-customize -a overcloud-realtime-compute.qcow2 --run-command \
   'subscription-manager attach --pool [pool-ID]'

6. Add the repositories necessary for Red Hat OpenStack Platform with NFV.

   virt-customize -a overcloud-realtime-compute.qcow2 --run-command \
   'sudo subscription-manager repos --enable=rhel-8-for-x86_64-baseos-eus-rpms \
   --enable=rhel-8-for-x86_64-appstream-eus-rpms \
   --enable=rhel-8-for-x86_64-highavailability-eus-rpms \
   --enable=ansible-2.9-for-rhel-8-x86_64-rpms \
   --enable=openstack-16.2-for-rhel-8-x86_64-rpms \
   --enable=rhel-8-for-x86_64-nfv-rpms \
   --enable=fast-datapath-for-rhel-8-x86_64-rpms'

7. Create a script to configure real-time capabilities on the image.

   (undercloud) [stack@undercloud-0 ~]$ cat <<'EOF' > rt.sh
     #!/bin/bash
   
     set -eux
   
     dnf -v -y --setopt=protected_packages= erase kernel.$(uname -m)
     dnf -v -y install kernel-rt kernel-rt-kvm tuned-profiles-nfv-host
     grubby --set-default /boot/vmlinuz*rt*
     EOF

8. Run the script to configure the real-time image:

   (undercloud) [stack@undercloud-0 ~]$ virt-customize -a overcloud-realtime-compute.qcow2 -v --run rt.sh 2>&1 | tee virt-customize.log

   Note

   If you see the following line in the rt.sh script output, "grubby fatal error: unable to find a suitable template", you can ignore this error.

9. Examine the virt-customize.log file that resulted from the previous command, to check that the packages installed correctly using the rt.sh script .

   (undercloud) [stack@undercloud-0 ~]$ cat virt-customize.log | grep Verifying
   
     Verifying  : kernel-3.10.0-957.el7.x86_64                                 1/1
     Verifying  : 10:qemu-kvm-tools-rhev-2.12.0-18.el7_6.1.x86_64              1/8
     Verifying  : tuned-profiles-realtime-2.10.0-6.el7_6.3.noarch              2/8
     Verifying  : linux-firmware-20180911-69.git85c5d90.el7.noarch             3/8
     Verifying  : tuned-profiles-nfv-host-2.10.0-6.el7_6.3.noarch              4/8
     Verifying  : kernel-rt-kvm-3.10.0-957.10.1.rt56.921.el7.x86_64            5/8
     Verifying  : tuna-0.13-6.el7.noarch                                       6/8
     Verifying  : kernel-rt-3.10.0-957.10.1.rt56.921.el7.x86_64                7/8
     Verifying  : rt-setup-2.0-6.el7.x86_64                                    8/8

10. Relabel SELinux:

    (undercloud) [stack@undercloud-0 ~]$ virt-customize -a overcloud-realtime-compute.qcow2 --selinux-relabel

11. Extract vmlinuz and initrd:

    (undercloud) [stack@undercloud-0 ~]$ mkdir image
    (undercloud) [stack@undercloud-0 ~]$ guestmount -a overcloud-realtime-compute.qcow2 -i --ro image
    (undercloud) [stack@undercloud-0 ~]$ cp image/boot/vmlinuz-3.10.0-862.rt56.804.el7.x86_64 ./overcloud-realtime-compute.vmlinuz
    (undercloud) [stack@undercloud-0 ~]$ cp image/boot/initramfs-3.10.0-862.rt56.804.el7.x86_64.img ./overcloud-realtime-compute.initrd
    (undercloud) [stack@undercloud-0 ~]$ guestunmount image

    Note

    The software version in the vmlinuz and initramfs filenames vary with the kernel version.

12. Upload the image:

    (undercloud) [stack@undercloud-0 ~]$ openstack overcloud image upload --update-existing --os-image-name overcloud-realtime-compute.qcow2

1. Create an RT-KVM flavor on the overcloud:

   # openstack flavor create  r1.small 99 4096 20 4
   # openstack flavor set --property hw:cpu_policy=dedicated 99
   # openstack flavor set --property hw:cpu_realtime=yes 99
   # openstack flavor set --property hw:mem_page_size=1GB 99
   # openstack flavor set --property hw:cpu_realtime_mask="^0-1" 99
   # openstack flavor set --property hw:cpu_emulator_threads=isolate 99

2. Launch an RT-KVM instance:

   # openstack server create  --image <rhel> --flavor r1.small --nic net-id=<dpdk-net> test-rt

3. To verify that the instance uses the assigned emulator threads, run the following command:

   # virsh dumpxml <instance-id> | grep vcpu -A1
   <vcpu placement='static'>4</vcpu>
   <cputune>
     <vcpupin vcpu='0' cpuset='1'/>
     <vcpupin vcpu='1' cpuset='3'/>
     <vcpupin vcpu='2' cpuset='5'/>
     <vcpupin vcpu='3' cpuset='7'/>
     <emulatorpin cpuset='0-1'/>
     <vcpusched vcpus='2-3' scheduler='fifo'
     priority='1'/>
   </cputune>