Re: [RFC][PATCH 02/22] sched: add extended scheduling interface

[Tommaso Cucinotta]

Il 12/11/2010 17:38, Steven Rostedt ha scritto:
> A while ago I implemented an EDF scheduler for a client (before working
> with Red Hat), and one thing they asked about was having a "soft group",
> which was basically: This group is guaranteed X runtime in Y period, but
> if the system is idle, let the group run, even if it has exhausted its X
> runtime.
>
> Is this supported?
Actually, I know that Dario has an implementation of exactly this 
feature (and it used to be implemented in our previous scheduler as 
well, i.e., the old AQuoSA stuff):
a per-task flag, when enabled, allows to put temporarily the task into 
SCHED_OTHER when its budget is exhausted. Therefore, it will be allowed 
to run for more than its budget but without breaking the temporal 
isolation with the other SCHED_DEADLINE tasks. Furthermore, it won't 
starve other SCHED_OTHER tasks, as it will compete with them for the CPU 
during the budget-exhausted time windows.

    T.

--
Tommaso Cucinotta, Computer Engineering PhD, Researcher
ReTiS Lab, Scuola Superiore Sant'Anna, Pisa, Italy
Tel +39 050 882 024, Fax +39 050 882 003
http://retis.sssup.it/people/tommaso

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