pg_autovacuum questions

Hi all,
only two questions:
1) where is the documentation about the
meanings of option passed to pg_autovacuum

2) Is it normal that a strace wake up it during a sleep?

From linux doc:
sleep() makes the current process sleep until seconds
seconds have elapsed or a signal arrives which is not ignored.

for fix this is better substitute each sleep with:

int a = <second_to_sleep>
while (a>0) a=sleep(a);

( I didn't find the signal to ignore :-) )

Regards
Gaetano Mendola