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schedulingfreertosrtos

Are there advantages to using earliest deadline first?

In dynamic scheduling, you have primarily two options: Earliest deadline first (EDF) or least laxity first (LLF). LLF is preferable in a multiple-core architecture, because in it, it is possible that low-execution time jobs that have high laxity will prevent high-execution low-laxity time jobs from executing before their deadline.

But what advantages do we have using EDF? Is it the lower resource cost?

Solution

  • One of the answers is paying attention to what type of tasks are most common in a given Schedule. If there are a lot of ones with low laxity, but some of them with

    1. high, and some with
    2. low execution time,

    then it may be beneficial to use EDF, since the 2nd ones will be executed first. Otherwise, they would've been executed second and it would inevitably lead to them violating the deadline.