Probabilistic task model

[Sophie Quinton]

[This problem was presented by Peter Zijlstra during his ECRTS'17 keynote talk, see slide 13]

Probabilistic task model.

There are a number of places where probabilistic (like) things pop up.

• unprivileged GRUB would require a per-task limit on allows overrun
• measurement based WCET, typically results in a distribution of sorts
• SoftRT many stream workloads that want to maximize machine utilization, lower WCET budget to increase efficiency but then rely on overrun / unused bandwidth reclaim to deal with peaks.

If we extend the task model with 1 more variable that is a 'variance' on budget, for example a 0-sum limit on overrun (overrun is added to the sum, and underrun subtracted from the sum and is limited to [0,x]) can this be usefully employed by the scheduling function?