| | Subject | Re: [RFC][PATCH 09/22] sched: add period support for -deadline tasks | | From | Raistlin <> | | Date | Thu, 11 Nov 2010 20:31:23 +0100 |
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On Thu, 2010-11-11 at 20:17 +0100, Peter Zijlstra wrote: > On Fri, 2010-10-29 at 08:34 +0200, Raistlin wrote: > > Make it possible to specify a period (different or equal than > > deadline) for -deadline tasks. > > > I would expect it to be: > > runtime <= deadline <= period > Well, apart from that really unhappy comment/changelog, it should be like that in the code, and if it's not, it is what I meant and I'll change to that as soon as I can! :-)
Since you spotted it... The biggest issue here is admission control test. Right now this is done against task's bandwidth, i.e., sum_i(runtime_i/period_i)<=threshold, but it is unfortunately wrong... Or at least very, very loose, to the point of being almost useless! :-(
The more correct --in the sense that it at least yield a sufficient (not necessary!) condition-- thing to do would be sum_i(runtime_i/min{deadline_i,period_i})<=threshold. So, what you think we should do? Can I go for this latter option?
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] |