Re: [RFD] sched/deadline: Support single CPU affinity

From: Peter Zijlstra
Date: Tue Dec 13 2016 - 05:21:48 EST


On Thu, Nov 10, 2016 at 11:01:59AM +0100, Tommaso Cucinotta wrote:
>
> Just a note: if you want to recover arbitrary task affinities, you can re-cast your above test like this:
>
> for_each_processor(cpu)
> \sum U[t]/A[t] \leq 1 (or U_max), for each task t on cpu, with utilization U[t] and A[t] tasks overall in its affinity mask
>

Do I read it correct when I interpret A[t] as the number of CPUs in its
affinity mask?

For A[t] == 1, that reduces to the UP case:

\Sum U[t] \leq 1

and A[t] = N that reduces to the G-EDF case:

\Sum U[t] \leq N


Also, does recoverable mean a bound tardiness, or is that something
weaker still?