INFORMATION_SCHEMA.QUERY_RESPONSE_TIME is empty

Hi there!
I have problem
mysql> SELECT * from INFORMATION_SCHEMA.QUERY_RESPONSE_TIME ;
±---------------±------±---------------+
| time | count | total |
±---------------±------±---------------+
| 0.000001 | 0 | 0.000000 |
| 0.000010 | 0 | 0.000000 |
| 0.000100 | 0 | 0.000000 |
| 0.001000 | 0 | 0.000000 |
| 0.010000 | 0 | 0.000000 |
| 0.100000 | 0 | 0.000000 |
| 1.000000 | 0 | 0.000000 |
| 10.000000 | 0 | 0.000000 |
| 100.000000 | 0 | 0.000000 |
| 1000.000000 | 0 | 0.000000 |
| 10000.000000 | 0 | 0.000000 |
| 100000.000000 | 0 | 0.000000 |
| 1000000.000000 | 0 | 0.000000 |
| TOO LONG | 0 | TOO LONG |
±---------------±------±---------------+
14 rows in set (0.00 sec)

but slow queries exists.
Could you explane What I do wrong? )))

Variable_name: version
Value: 5.5.27-28.0-log
*************************** 366. row ***************************
Variable_name: version_comment
Value: Percona Server (GPL), Release 28.0
*************************** 367. row ***************************
Variable_name: version_compile_machine
Value: x86_64
*************************** 368. row ***************************
Variable_name: version_compile_os
Value: Linux

| Qcache_free_blocks | 6072 |
| Qcache_free_memory | 244855696 |
| Qcache_hits | 19989810 |
| Qcache_inserts | 10049 |
| Qcache_lowmem_prunes | 0 |
| Qcache_not_cached | 224 |
| Qcache_queries_in_cache | 10049 |
| Qcache_total_blocks | 26178 |
| Queries | 20000438 |
| Questions | 20000438 |

you have to set the variable

query_response_time_stats

i.e.

mysql> set global query_response_time_stats=ON;

Then it will start filling up the table with stats (In our case 321000 queries in 2 mins!!).

Oh! It’s so simple. I read all cross hawto’s and did not find it.
Many thanks.

(In our case 321000 queries in 2 mins!!)
It’s just tests. But this tests show me without query cache perfomance is higher in 5 times

Narrow place is here:
SHOW PROCESSLIST;
| 244 | testtable | localhost | glavsport | Query | 0 | Waiting for query cache lock | SELECT t0.id t0.id,t0.name t0.name,t0.icon t0.icon,t0.text t0.text,IFNULL(c | 0 | 0 | 1 |
101 rows in set (0.00 sec)

Thanks a lot!