On Thu, Nov 19, 2009 at 04:00:46PM +0100, Kay Sievers wrote: > Yeah, it would not be as simple as your patch. It probably involves a > way to get a file descriptor per listener, to let the kernel know if > anybody is interested, and to auto-cleanup when the listener dies, and > to have per instance timers. This would seem to involve a lot of extra locking in the block submission and completion code. I don't think it's ideal. How about this: * idle_hysteresis contains a value. If it's greater than 0, attempting to increase it will give -EINVAL. It can be polled. * On idle state transition, applications listening to the stat sysfs node will get woken. The stat output will include the number of msecs that the disk has been idle. If this is less than the application requested, it can set a timer to wake it up again in the future and recheck. * When an application exits, if (and only if) it wrote a value to idle_hysteresis, it should set this back to 0. This will notify any other apps, which may then set their own wakeup time. It's not beautiful but it satisfies the constraints. There's a minimum of extra wakeups, it doesn't complicate the block path any further and multiple applications can take advantage of it. -- 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
