GB-PANDAS: Throughput and heavy-traffic optimality analysis for affinity scheduling

TL;DR

This paper introduces GB-PANDAS, a new affinity scheduling algorithm that is throughput and heavy-traffic optimal, handling multiple data locality levels with arbitrary service time distributions, significantly improving delay performance in data center workloads.

Contribution

The paper proposes GB-PANDAS, a novel affinity scheduling algorithm that is proven to be throughput and heavy-traffic optimal for systems with multiple data locality levels and arbitrary service time distributions.

Findings

GB-PANDAS achieves throughput and heavy-traffic optimality.

It significantly reduces mean delay compared to existing algorithms.

Simulation shows it outperforms JSQ-MaxWeight by twofold in delay performance.

Abstract

Dynamic affinity scheduling has been an open problem for nearly three decades. The problem is to dynamically schedule multi-type tasks to multi-skilled servers such that the resulting queueing system is both stable in the capacity region (throughput optimality) and the mean delay of tasks is minimized at high loads near the boundary of the capacity region (heavy-traffic optimality). As for applications, data-intensive analytics like MapReduce, Hadoop, and Dryad fit into this setting, where the set of servers is heterogeneous for different task types, so the pair of task type and server determines the processing rate of the task. The load balancing algorithm used in such frameworks is an example of affinity scheduling which is desired to be both robust and delay optimal at high loads when hot-spots occur. Fluid model planning, the MaxWeight algorithm, and the generalized $c\mu$-rule are among the first algorithms proposed for affinity scheduling that have theoretical guarantees on being optimal in different senses, which will be discussed in the related work section. All these algorithms are not practical for use in data center applications because of their non-realistic assumptions. The join-the-shortest-queue-MaxWeight (JSQ-MaxWeight), JSQ-Priority, and weighted-workload algorithms are examples of load balancing policies for systems with two and three levels of data locality with a rack structure. In this work, we propose the Generalized-Balanced-Pandas algorithm (GB-PANDAS) for a system with multiple levels of data locality and prove its throughput optimality. We prove this result under an arbitrary distribution for service times, whereas most previous theoretical work assumes geometric distribution for service times. The extensive simulation results show that the GB-PANDAS algorithm alleviates the mean delay and has a better performance than the JSQ-MaxWeight algorithm by twofold