Metrics for scalability measurement Metrics for scalability measurement¶
Note
This feature has been deprecated in Percona Server 5.7.16-10. 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. These metrics allow using Little’s Law, queuing 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¶ Command Line: Yes Scope: Global Dynamic: Yes Variable Type: String Default Value: OFFValues: 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¶ Variable Type: Numeric
This status variable shows total time elapsed, in microseconds, since metrics collection was started.
-
variable
scalability_metrics_queries¶ Variable Type: Numeric
This status variable shows number of completed queries since metrics collection was started.
-
variable
scalability_metrics_concurrency¶ Variable Type: Numeric
This status variable shows number of queries currently executed.
-
variable
scalability_metrics_totaltime¶ 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¶ Variable Type: Numeric
This counter accounts the non-idle server time, that is, time when at least one query was executing.
