Metrics for scalability measurement

Metrics for scalability measurement

Note

This feature has been deprecated in Percona Server 5.5.53-38.5. Users who have installed this plugin but are not using its capability are advised to uninstall the plugin due to known crashing bugs.

Percona Server has implemented extra scalability metrics in 5.5.37-35.0. These metrics allow using Little’s Law, queueing theory, and Universal Scalability Law to gain insights into server performance. This feature is implemented as a plugin.

Installation

Scalability Metrics plugin is shipped with Percona Server, but it is not installed by default. To enable the plugin you must run the following command:

INSTALL PLUGIN scalability_metrics SONAME 'scalability_metrics.so';

You can check if the plugin is loaded correctly by running:

SHOW PLUGINS;

The plugin should be listed in the output:

+--------------------------------+----------+--------------------+------------------------+---------+
| Name                           | Status   | Type               | Library                | License |
+--------------------------------+----------+--------------------+------------------------+---------+
...
| scalability_metrics            | ACTIVE   | AUDIT              | scalability_metrics.so | GPL     |
+--------------------------------+----------+--------------------+------------------------+---------+

System Variables

variable scalability_metrics_control
Version Info:
Command Line:

Yes
Scope:

Global
Dynamic:

Yes
Variable Type:

String
Default Value:

OFF
Values:

OFF, ON, RESET

This variable can be used to enable and disable the collection of metrics for scalability measurement. By setting the value to RESET all counters will be reset while continuing to count metrics.

Status Variables

variable scalability_metrics_elapsedtime
Version Info:
Variable Type:

Numeric

This status variable shows total time elapsed, in microseconds, since metrics collection was started.

variable scalability_metrics_queries
Version Info:
Variable Type:

Numeric

This status variable shows number of completed queries since metrics collection was started.

variable scalability_metrics_concurrency
Version Info:
Variable Type:

Numeric

This status variable shows number of queries currently executed.

variable scalability_metrics_totaltime
Version Info:
Variable Type:

Numeric

This status variable shows total execution time of all queries, including the in-progress time of currently executing queries, in microseconds (ie. if two queries executed with 1 second of response time each, the result is 2 seconds).

variable scalability_metrics_busytime
Version Info:
Variable Type:

Numeric

This counter accounts the non-idle server time, that is, time when at least one query was executing.

Version Specific Information

  • 5.5.37-35.0 Scalability Metrics plugin has been implemented in Percona Server.
  • 5.5.53-38.4 Feature has been removed.
  • 5.5.53-38.5 Feature has been added back but deprecated.
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