66 lines
3.8 KiB
YAML
66 lines
3.8 KiB
YAML
---
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features:
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Compute nodes using the libvirt driver can now report ``PCPU`` inventory.
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This is consumed by instances with dedicated (pinned) CPUs. This can be
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configured using the ``[compute] cpu_dedicated_set`` config option. The
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scheduler will automatically translate the legacy ``hw:cpu_policy`` flavor
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extra spec or ``hw_cpu_policy`` image metadata property to ``PCPU``
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requests, falling back to ``VCPU`` requests only if no ``PCPU`` candidates
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are found. Refer to the help text of the ``[compute] cpu_dedicated_set``,
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``[compute] cpu_shared_set`` and ``vcpu_pin_set`` config options for more
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information.
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Compute nodes using the libvirt driver will now report the
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``HW_CPU_HYPERTHREADING`` trait if the host has hyperthreading. The
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scheduler will automatically translate the legacy ``hw:cpu_thread_policy``
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flavor extra spec or ``hw_cpu_thread_policy`` image metadata property to
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either require or forbid this trait.
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A new configuration option, ``[compute] cpu_dedicated_set``, has been
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added. This can be used to configure the host CPUs that should be used for
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``PCPU`` inventory. Refer to the help text of the ``[compute]
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cpu_dedicated_set`` config option for more information.
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The ``[compute] cpu_shared_set`` configuration option will now be used to
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configure the host CPUs that should be used for ``VCPU`` inventory,
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replacing the deprecated ``vcpu_pin_set`` option. Refer to the help text of
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the ``[compute] cpu_shared_set`` config option for more information.
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A new configuration option, ``[workarounds] disable_fallback_pcpu_query``,
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has been added. When creating or moving pinned instances, the scheduler will
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attempt to provide a ``PCPU``-based allocation, but can also fallback to a legacy
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``VCPU``-based allocation. This fallback behavior is enabled by
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default to ensure it is possible to upgrade without having to modify compute
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node configuration, but it results in an additional request for allocation
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candidates from placement. This can have a slight performance impact and is
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unnecessary on new or upgraded deployments where all compute nodes have been
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correctly configured to report ``PCPU`` inventory. The ``[workarounds]
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disable_fallback_pcpu_query`` config option can be used to disable this
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fallback allocation candidate request, meaning only ``PCPU``-based
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allocation candidates will be retrieved. Refer to the help text of the
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``[workarounds] disable_fallback_pcpu_query`` config option for more
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information.
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deprecations:
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The ``vcpu_pin_set`` configuration option has been deprecated. You should
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migrate host CPU configuration to the ``[compute] cpu_dedicated_set`` or
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``[compute] cpu_shared_set`` config options, or both. Refer to the help
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text of these config options for more information.
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upgrade:
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Previously, if the ``vcpu_pin_set`` configuration option was not defined,
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the libvirt driver would count all available host CPUs when calculating
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``VCPU`` inventory, regardless of whether those CPUs were online or not.
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The driver will now only report the total number of online CPUs. This
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should result in fewer build failures on hosts with offlined CPUs.
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Previously, if an instance was using the ``isolate`` CPU thread policy on a
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host with SMT (hyperthreading) enabled, the libvirt driver would fake a
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non-SMT host by marking the thread sibling(s) for each host CPU used by the
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instance as reserved and unusable. This is no longer the case. Instead,
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instances using the policy will be scheduled only to hosts that do not
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report the ``HW_CPU_HYPERTHREADING`` trait. If you have workloads that
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require the ``isolate`` policy, you should configure some or all of your
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hosts to disable SMT.
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