33 lines
2.0 KiB
YAML
33 lines
2.0 KiB
YAML
---
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upgrade:
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- |
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A new config option has been added to the OpenvSwitch plugin
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``[os_vif_ovs]default_qos_type``. This option controls
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the Default tc qdisc applied to a kernel interface attached to OpenvSwitch
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on Linux hosts. As of this release, the default tc qdisc is ``linux-noop``
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other supported values are ``linux-htb``, ``linux-hfsc``,
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``linux-sfq``, ``linux-codel`` and ``linux-fq_codel``.
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before this release the default qdisc was undefined. older kernels did not
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apply /proc/sys/net/core/default_qdisc to tap devices. newer kernels such
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as the one found in rhel 9 do. This can significantly impact performance.
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See bug https://bugs.launchpad.net/os-vif/+bug/2017868 for more details.
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The default ``linux-noop`` should perform well for all use-cases so no
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explicit action is required on upgrade however it should be noted that
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the default_qos_type is only set when a port is first created. As such
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this fix will not take effect until the next time the vm interface is
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recreated. If you change this value for an existing port it will only
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take effect after a hard reboot of the VM or a move operation.
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fixes:
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- |
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A significant performance regression was observed on a subset of Linux
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kernels and sysctl configurations resulting in a reduction of throughput
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to between 10% of the prior performance for small packets and 50% for
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large packets. This has now been resolved by setting a default
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qos_type on ovs interfaces when they are first created. To mimic libvirt's
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undocumented behavior the ``linux-noop`` type is set on the ovs port when
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it is first created. This will be overridden by neutron if a qos policy
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is defined for a port and is simply the initial value to use when first
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adding a port to OpenvSwitch. The default QoS type applied can be
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controlled by the ``[os_vif_ovs]default_qos_type`` config operation.
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See bug https://bugs.launchpad.net/os-vif/+bug/2017868 for more details. |