Update Workload Balance strategy documentation
Adds additional parameter and usage explanations and combined example. Closes-Bug: #2111848 Change-Id: Id0de4d56fa7083388ad82c61596e7484431d465b
This commit is contained in:
Ronelle Landy
@@ -11,25 +11,35 @@ Synopsis
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.. watcher-term:: watcher.decision_engine.strategy.strategies.workload_balance.WorkloadBalance
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Requirements
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------------
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None.
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Metrics
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*******
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The *workload_balance* strategy requires the following metrics:
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======================= ============ ======= =========================
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metric service name plugins comment
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======================= ============ ======= =========================
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``cpu`` ceilometer_ none
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``memory.resident`` ceilometer_ none
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======================= ============ ======= =========================
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======================= ============ ======= =========== ======================
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metric service name plugins unit comment
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======================= ============ ======= =========== ======================
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``cpu`` ceilometer_ none percentage CPU of the instance.
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Used to calculate the
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threshold
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``memory.resident`` ceilometer_ none MB RAM of the instance.
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Used to calculate the
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threshold
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======================= ============ ======= =========== ======================
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.. _ceilometer: https://docs.openstack.org/ceilometer/latest/admin/telemetry-measurements.html#openstack-compute
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**Notes**
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* The parameters above reference the instance CPU or RAM usage, but
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the threshold calculation is based of the CPU/RAM usage on the hypervisor.
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* The RAM usage can be calculated based on the RAM consumed by the instance,
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and the available RAM on the hypervisor.
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* The CPU percentage calculation relies on the CPU load, but also on the number
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of CPUs on the hypervisor.
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* The memory host metric is calculated by summing the RAM usage of each
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instance on the host. This measure is close to the real usage, but is not
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the exact usage on the host.
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Cluster data model
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******************
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@@ -64,16 +74,28 @@ Configuration
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Strategy parameters are:
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============== ====== ==================== ====================================
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parameter type default Value description
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============== ====== ==================== ====================================
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``metrics`` String 'instance_cpu_usage' Workload balance base on cpu or ram
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utilization. Choices:
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['instance_cpu_usage',
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'instance_ram_usage']
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``threshold`` Number 25.0 Workload threshold for migration
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``period`` Number 300 Aggregate time period of ceilometer
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============== ====== ==================== ====================================
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================ ====== ==================== ==================================
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parameter type default value description
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================ ====== ==================== ==================================
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``metrics`` String 'instance_cpu_usage' Workload balance base on cpu or
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ram utilization. Choices:
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['instance_cpu_usage',
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'instance_ram_usage']
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``threshold`` Number 25.0 Workload threshold for migration.
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Used for both the source and the
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destination calculations.
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Threshold is always a percentage.
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``period`` Number 300 Aggregate time period of
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ceilometer
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``granularity`` Number 300 The time between two measures in
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an aggregated timeseries of a
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metric.
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This parameter is only used
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with the Gnocchi data source,
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and it must match to any of the
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valid archive policies for the
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metric.
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================ ====== ==================== ==================================
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Efficacy Indicator
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------------------
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@@ -89,14 +111,36 @@ to: https://specs.openstack.org/openstack/watcher-specs/specs/mitaka/implemented
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How to use it ?
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---------------
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Create and audit template using the Workload Balancing strategy.
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.. code-block:: shell
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$ openstack optimize audittemplate create \
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at1 workload_balancing --strategy workload_balance
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Run an audit using the Workload Balance strategy where
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the aim is to get a plan to move VMs from any host where the
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CPU usage is over the threshold of 26%, to a host where the
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utilization of CPU is under the threshold.
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The measurements of CPU utilization are taken from Ceilometer
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with an aggregate period of 310.
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.. code-block:: shell
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$ openstack optimize audit create -a at1 -p threshold=26.0 \
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-p period=310 -p metrics=instance_cpu_usage
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Run an audit using the Workload Balance strategy to
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obtain a plan to balance VMs over hosts with a threshold of 20%.
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In this case, the stipulation of the Ceilometer CPU utilization
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metric measurement is a combination of period and granularity.
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.. code-block:: shell
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$ openstack optimize audit create -a at1 \
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-p granularity=30 -p threshold=20 -p period=300 \
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-p metrics=instance_cpu_usage --auto-trigger
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External Links
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--------------
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@@ -28,13 +28,16 @@ LOG = log.getLogger(__name__)
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class WorkloadBalance(base.WorkloadStabilizationBaseStrategy):
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"""[PoC]Workload balance using live migration
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"""Workload balance using live migration
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*Description*
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It is a migration strategy based on the VM workload of physical
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servers. It generates solutions to move a workload whenever a server's
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CPU or RAM utilization % is higher than the specified threshold.
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The threshold specified is used to trigger a migration,
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but it is also used to determine if there is an available host,
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with low enough utilization, to migrate the instance.
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The VM to be moved should make the host close to average workload
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of all compute nodes.
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@@ -48,7 +51,6 @@ class WorkloadBalance(base.WorkloadStabilizationBaseStrategy):
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*Limitations*
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- This is a proof of concept that is not meant to be used in production
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- We cannot forecast how many servers should be migrated. This is the
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reason why we only plan a single virtual machine migration at a time.
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So it's better to use this algorithm with `CONTINUOUS` audits.
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@@ -105,7 +107,9 @@ class WorkloadBalance(base.WorkloadStabilizationBaseStrategy):
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"default": "instance_cpu_usage"
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},
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"threshold": {
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"description": "workload threshold for migration",
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"description": "Workload threshold for migration - "
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"used for source and destination hosts. "
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"It is always a percentage value.",
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"type": "number",
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"default": 25.0
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},
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