question about long_query_time

I have set my db serser’s long_query_time to 0,but it seems it doesn’t seem work!

mysql> show global variables like ‘%long%’;
| Variable_name | Value |
| long_query_time | 0.000000 |
1 row in set (0.00 sec)

The initial value is 5s,but after change to 0,it log some queries,but not all!

Can anybody tell me why?

There are old sessions that remain open and have not yet been affected by the change to the global variable. Percona’s patches have a method to force this to take effect: ry_time

:o Thank you very much