On Wed, Nov 18, 2009 at 08:47:37PM +0100, Kay Sievers wrote: > On Wed, Nov 18, 2009 at 20:40, Matthew Garrett <mjg@xxxxxxxxxx> wrote: > > On Wed, Nov 18, 2009 at 08:30:07PM +0100, Kay Sievers wrote: > > > >> Wouldn't it be good enough, if we add a file "idle_since" which > >> contains the time of the actual disk idle time, and userspace can > >> schedule a re-examination of that value at the actual end of the idle > >> time it is looking for? > > > > That would require either polling or waking up a userspace application > > on every disk access. Doing it in-kernel involves only a single timer > > wakeup for every active/idle transition. > > How would it? If you look for, like a 60 seconds timeout, and the file > contains 20, you schedule a wakeup in 40 seconds. If the file after > the 40 seconds contains 60, you reached your idle timeout exactly at > that moment, if it's less, then you re-calculate and start from the > beginning. How is that not polling? You'll repeatedly read a file looking for a value that may never appear - imagine the case where you're waiting for 60 seconds of idleness, but the disk always becomes active again after 50. -- Matthew Garrett | mjg59@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
