TUTORIAL IT

Here is another micro-benchmark to prove that Performance Schema overhead is so serious.

non-persistent connections from remote machine, 100 concurrency, MySQL 5.6.13

performance_schema	connections per second
0	39525.62
1(default)	26304.53

Benchmark command is the same as what I published long time ago.

I understand almost all applications dont need 20000~30000 connections per second per instance, but latency increase should be considered. It would be better to make performance_schema parameter dynamic, and set 0 as default.