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Merge "docs: Add notes about IoOpsWeigher, BuildFailureWeigher"

changes/29/813729/2
Zuul 2 months ago
committed by Gerrit Code Review
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c5c2cc0341
  1. 40
      doc/source/admin/scheduling.rst

40
doc/source/admin/scheduling.rst

@ -853,7 +853,6 @@ Hosts are weighted based on the following config options:
- :oslo.config:option:`filter_scheduler.host_subset_size`
- :oslo.config:option:`filter_scheduler.weight_classes`
``RAMWeigher``
~~~~~~~~~~~~~~
@ -870,7 +869,6 @@ back to the :oslo.config:option:`filter_scheduler.ram_weight_multiplier`.
If more than one value is found for a host in aggregate metadata, the minimum
value will be used.
``CPUWeigher``
~~~~~~~~~~~~~~
@ -887,7 +885,6 @@ back to the :oslo.config:option:`filter_scheduler.cpu_weight_multiplier`. If
more than one value is found for a host in aggregate metadata, the minimum
value will be used.
``DiskWeigher``
~~~~~~~~~~~~~~~
@ -902,7 +899,6 @@ back to the :oslo.config:option:`filter_scheduler.disk_weight_multiplier`. If
more than one value is found for a host in aggregate metadata, the minimum value
will be used.
``MetricsWeigher``
~~~~~~~~~~~~~~~~~~
@ -929,14 +925,17 @@ metrics weight multiplier. Otherwise, it will fall back to the
one value is found for a host in aggregate metadata, the minimum value will
be used.
``IoOpsWeigher``
~~~~~~~~~~~~~~~~
The weigher can compute the weight based on the compute node
host's workload. The default is to preferably choose light workload compute
hosts. If the multiplier is positive, the weigher prefer choosing heavy
workload compute hosts, the weighing has the opposite effect of the default.
The weigher can compute the weight based on the compute node host's workload.
This is calculated by examining the number of instances in the ``building``
``vm_state`` or in one of the following ``task_state``\ 's:
``resize_migrating``, ``rebuilding``, ``resize_prep``, ``image_snapshot``,
``image_backup``, ``rescuing``, or ``unshelving``.
The default is to preferably choose light workload compute hosts. If the
multiplier is positive, the weigher prefers choosing heavy workload compute
hosts, the weighing has the opposite effect of the default.
Starting with the Stein release, if per-aggregate value with the key
``io_ops_weight_multiplier`` is found, this
@ -1006,6 +1005,8 @@ the
If more than one value is found for a host in aggregate metadata, the minimum
value will be used.
.. _build-failure-weigher:
``BuildFailureWeigher``
~~~~~~~~~~~~~~~~~~~~~~~
@ -1020,6 +1021,17 @@ build failure weight multiplier. Otherwise, it will fall back to the
more than one value is found for a host in aggregate metadata, the minimum
value will be used.
.. important::
The :oslo.config:option:`filter_scheduler.build_failure_weight_multiplier`
option defaults to a very high value. This is intended to offset weight
given by other enabled weighers due to available resources, giving this
weigher priority. However, not all build failures imply a problem with the
host itself - it could be user error - but the failure will still be
counted. If you find hosts are frequently reporting build failures and
effectively being excluded during scheduling, you may wish to lower the
value of the multiplier.
.. _cross-cell-weigher:
``CrossCellWeigher``
@ -1028,11 +1040,11 @@ value will be used.
.. versionadded:: 21.0.0 (Ussuri)
Weighs hosts based on which cell they are in. "Local" cells are preferred when
moving an instance. Use configuration option
:oslo.config:option:`filter_scheduler.cross_cell_move_weight_multiplier` to
control the weight. If per-aggregate value with the key
`cross_cell_move_weight_multiplier` is found, this value would be chosen as the
cross-cell move weight multiplier. Otherwise, it will fall back to the
moving an instance.
If per-aggregate value with the key `cross_cell_move_weight_multiplier` is
found, this value would be chosen as the cross-cell move weight multiplier.
Otherwise, it will fall back to the
:oslo.config:option:`filter_scheduler.cross_cell_move_weight_multiplier`. If
more than one value is found for a host in aggregate metadata, the minimum
value will be used.

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