Hi! > > > > I don't know. There are other interfaces too, like sysfs attributes, > > > > that would have to be handled specially. On the whole, the freezer > > > > seems much, much simpler. > > > > > > OK, then non-device files on "regular" filesystems. > > > > Would you like to write a first-pass patch? I don't think it will > > work. > > If somebody doesn't beat me to it, I'll do that (first implemented > with a global rw-sem). Cool! l > > Doing that seems like a lot of work, just as modifying every driver > > does. Changing a few kernel entry points is simpler, but I'm pretty > > sure it won't work. For instance, tasks can block arbitrarily long on > > read calls (waiting for data to arrive); you can't allow such things to > > prevent the system from suspending. > > But we already do: either > > a) it's in interruptible sleep (I/O on sockets, pipes, etc), and > freezing simply interrupts it, or > > b) it's in uninterruptible sleep and suspend will wait it out (or > time out). > > In the new scheme we could retain that part of the freezer: interrupt > all tasks which are inside the critical region and wait for them to > exit the critical region. > > To put it in another way: it's still the freezer, it does all the same > things as the old freezer, except that the condition for freezing is > not that the task is out of the kernel, rather that it's out of the > disable_supend - enable_suspend region. As such it's not a big change > to the whole suspend system, and so there shouldn't be anything big > going wrong there. Disadvantage is it will add overhead to regular syscalls, at least initialy. That's why I implemented freezer initialy... Of course, suspend is more important than it was back then, and disadvantages of freezer are now well known, so maybe a little overhead in exchange of cleaner design is worth it...? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
