Bug #71808 Remove the TICK timer in performance_schema
Submitted: 23 Feb 2014 12:38 Modified: 31 Jan 2018 14:40
Reporter: Valeriy Kravchuk Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Performance Schema Severity:S3 (Non-critical)
Version:5.5, 5.6, 5.7 OS:Any
Assigned to: Marc Alff CPU Architecture:Any
Tags: missing manual, performance_schema, performance_timers

[23 Feb 2014 12:38] Valeriy Kravchuk
Description:
Manual for P_S.performance_timers table (http://dev.mysql.com/doc/refman/5.6/en/performance-timers-table.html) does NOT explain what TICK timer is actually expected to measure.

CYCLE timer is explained, purpose of NANOSECOND, MICROSECOND and MILLISECOND is clear from the name, but TICK is a mystery.

How to repeat:
Check the following outputs on Linux:

mysql>  select * from performance_schema.performance_timers;
+-------------+-----------------+------------------+----------------+
| TIMER_NAME  | TIMER_FREQUENCY | TIMER_RESOLUTION | TIMER_OVERHEAD |
+-------------+-----------------+------------------+----------------+
| CYCLE       |      1495487562 |                1 |             53 |
| NANOSECOND  |      1000000000 |                1 |            105 |
| MICROSECOND |         1000000 |                1 |             98 |
| MILLISECOND |            1037 |                1 |            120 |
| TICK        |             103 |                1 |            460 |
+-------------+-----------------+------------------+----------------+
5 rows in set (0,00 sec)

and Windows (5.6.16, Oracle binaries, different hardware):

mysql> select * from performance_schema.performance_timers;
+-------------+-----------------+------------------+----------------+
| TIMER_NAME  | TIMER_FREQUENCY | TIMER_RESOLUTION | TIMER_OVERHEAD |
+-------------+-----------------+------------------+----------------+
| CYCLE       |       993221031 |                1 |             81 |
| NANOSECOND  |            NULL |             NULL |           NULL |
| MICROSECOND |          974169 |                1 |             92 |
| MILLISECOND |            1029 |                1 |            108 |
| TICK        |            1230 |                1 |              9 |
+-------------+-----------------+------------------+----------------+
5 rows in set (0.00 sec)

Try to find out in the manual what is the meaning of TICK on Windows and why it's different in scale from the timer with the same name on Linux.

Suggested fix:
Document the purpose and possible values for TICK timer on all major supported platforms: Linux, Windows and Solaris (at least).
[24 Feb 2014 10:38] Umesh Shastry
Hello Valeriy,

Thank you for the bug report.
Verified as described.

Thanks,
Umesh
[5 Jul 2017 14:59] Marc Alff
The TICK timer should be removed, it has no real use.

Changing the bug report to a performance_schema bug, for removal.
[31 Jan 2018 14:40] Paul Dubois
Posted by developer:
 
Fixed in 8.0.4, 9.0.0.

The Performance Schema setup_timers table has been removed, as has
the TICK row in the performance_timers table.