| Subject | Re: [RFC][PATCH 20/22] sched: drafted deadline inheritance logic | From | Raistlin <> | Date | Sun, 14 Nov 2010 13:00:35 +0100 |
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On Thu, 2010-11-11 at 23:15 +0100, Peter Zijlstra wrote: > > Acting this way, we provide some kind of boosting to the lock-owner, > > still by using the existing (actually, slightly modified by the previous > > commit) pi-architecture. > > Right, so this is the trivial priority ceiling protocol extended to > bandwidth inheritance and we basically let the owner overrun its runtime > to release the shared resource. > We can call it that way. Basically, what we do is scheduling the lock-owner with the parameters, i.e., runtime and deadline, of the earliest deadline task blocked on it. As soon as such runtime depletes, we (1) _do_ postpone that deadline (again, according to earliest deadline lock-owner's relative deadline), but we also (2) immediately replenish the runtime _immediately_.
Acting like this we ensure the lock-owner won't hurt the guarantees provided to tasks with deadline earlier than all the tasks in its blocking chains (by means of (1)), and we also enable a quicker release of the lock (by means of (2)).
> Didn't look at it too closely, but yeah, that is a sensible first > approximation band-aid to keep stuff working. > I'll keep going this way then. :-)
Thanks, Dario -- <<This happens because I choose it to happen!>> (Raistlin Majere) ---------------------------------------------------------------------- Dario Faggioli, ReTiS Lab, Scuola Superiore Sant'Anna, Pisa (Italy)
http://blog.linux.it/raistlin / raistlin@ekiga.net / dario.faggioli@jabber.org [unhandled content-type:application/pgp-signature] |