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

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   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

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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

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3. Copy the default image:

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

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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

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   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]'

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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'

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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

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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

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   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

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10. Relabel SELinux:

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

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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

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    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

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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

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2. Launch an RT-KVM instance:

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

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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>

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