I have edited session.cookie_domain = ".mysite.in"
in php.ini to share one single session for same user across all the sub domains of my site.
But it is not working weird. Now if I open a session at "www.mysite.in", it gets shared with "mysite.in"(no www), but not with "oth.mysite.in".
PS : The session did not get shared to "mysite.in" before. So edit definitely has some effect.