Lingering issues in distributed scheduling

Florian Simatos (1) , Niek Bouman (1) , Sem Borst (1, 2)

1 TU/e - Eindhoven University of Technology [Eindhoven]
2 Alcatel-Lucent Bell Labs

Recent advances have resulted in queue-based algorithms for medium access control which operate in a distributed fashion, and yet achieve the optimal throughput performance of centralized scheduling algorithms. However, fundamental performance bounds reveal that the “cautious” activation rules involved in establish- ing throughput optimality tend to produce extremely large delays, typically growing exponentially in 1/(1−ρ), with ρ the load of the system, in contrast to the usual linear growth. Motivated by that issue, we explore to what extent more “aggressive” schemes can improve the delay performance. Our main finding is that aggressive acti- vation rules induce a lingering effect, where individual nodes retain possession of a shared resource for excessive lengths of time even while a majority of other nodes idle. Using central limit theorem type arguments, we prove that the idleness induced by the lingering effect may cause the delays to grow with 1/(1−ρ) at a quadratic rate. To the best of our knowledge, these are the first mathematical results illuminating the linger- ing effect and quantifying the performance impact. In addition extensive simulation experiments are conducted to illustrate and validate the various analytical results.

Mots clés: Delay performance; Distributed scheduling algorithms; Heavy traffic scaling; Wireless networks

Domaines: Réseaux et télécommunications [cs.NI]

Florian Simatos, Niek Bouman, Sem Borst. Lingering issues in distributed scheduling. Queueing Systems, 2014, 77 (2), pp.243-273. ⟨10.1007/s11134-014-9404-z⟩. ⟨hal-01888052⟩