On Sat, 2014-10-18 at 23:34 +0200, Peter Zijlstra wrote: > Same comment as before, that is an unbounded loop in a non preemptible > section and therefore violates RT design principles. > > We actually did talk about ways of fixing that. Right, and we should slap Paul for not showing up for it ;-) The decision that we came up with was to splice the current list onto a local list variable. And then we could go into a loop releasing the lock and grabbing it again. Each time pop a waiter off the list and doing the work of only one task at a time. This prevents doing large amounts of wake ups under a spinlock. The splice is required to only wake up those that are on the list when the wake up is called. This prevents waking up a task twice because it woke up, removed itself, and then added itself again. We must keep the semantics that a wake up only wakes up a task once. > > Also, I'm not entirely sure we want to do the cwait thing, it looks > painful. Yeah, I have to think about that some more too. I'm currently sitting in the airport waiting for my final leg of my flight. After 18 hours of travel, it is probably not too wise to review this work in my current state ;-) -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
