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  1. RHEL
  2. RHEL-21570

Critical performance degradation for input devices in virtio vnc session

    • qemu-kvm-8.2.0-3.el9
    • Blocker
    • Regression
    • sst_virtualization
    • ssg_virtualization
    • 22
    • 24
    • None
    • QE ack
    • False
    • Hide

      None

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    • None
    • None
    • s390x
    • None

      What were you trying to do that didn't work?

      Install a KVM guest graphically. The performance is so bad that it's practically not functional.

      Please provide the package NVR for which bug is seen:

      qemu-kvm-8.2.0-2.el9

      How reproducible:

      100%

      Steps to reproduce

      1. host# firewall-cmd --zone=public --add-port=5900-5999/tcp
      1. host# virt-install --memory 2048 --vcpus 2 --os-variant rhel8-unknown --graphics vnc,listen=0.0.0.0 --input keyboard,bus=virtio --input tablet,bus=virtio --disk size=10  --location <install-tree-url>

        (full xml below)

      1. Connect to the VNC session, e.g. with tigerVNC

      Expected results

      I can easily use the mouse cursor to select the controls of the graphical installer, esp. the "Continue button" in the bottom right corner.

      Actual results

      The cursor has lag, disappears and I can't hit the Continue button

      Additional info:

      1. This does not reproduce with QEMU 8.1.0-5
      2. I also tried the virtio mouse with the same results
      3. I tested this on s390x, will reach out for help on other archs
      4. On s390x this is the only way to do a graphical installation which is a hard requirement.
      5. ...
            <input type='keyboard' bus='virtio'>
              <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0004'/>
            </input>
            <input type='mouse' bus='virtio'>
              <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0005'/>
            </input>
            <graphics type='vnc' port='-1' autoport='yes' listen='0.0.0.0'>
              <listen type='address' address='0.0.0.0'/>
            </graphics>
            <audio id='1' type='none'/>
            <video>
              <model type='virtio' heads='1' primary='yes'/>
              <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0002'/>
            </video>
        ...

            thuth@redhat.com Thomas Huth
            smitterl@redhat.com Sebastian Mitterle
            Thomas Huth Thomas Huth
            Liang Cong Liang Cong
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              Created:
              Updated:
              Resolved: