I am using the new session management feature session_set_save_handler() from PHP4.

all other function is working fine, except function sess_gc($maxlifetime) .

It is not working.
It suppose to clean up the expired session record in my database.
I have configed the file php.ini.
session.gc_maxlifetime to 300 seconds.
and the default session.gc_probability is '1'.
anyone kow what does 'session.gc_probability' do?
do i have to increase the % of gc_probability?

anyone know when will the server run gc process?