Response Time Bounds for Typed DAG Parallel Tasks on Heterogeneous Multi-cores

TL;DR

This paper introduces two new worst-case response time bounds for typed scheduling of parallel DAG tasks on heterogeneous multi-cores, improving accuracy and addressing limitations of previous bounds.

Contribution

It proposes two novel bounds for WCRT analysis that are more precise and computationally efficient, with one leveraging detailed graph structure information.

Findings

New bounds are more accurate than existing ones.

The second bound is NP-hard to compute when the number of types varies.

Efficient algorithms are developed for fixed number of core types.

Abstract

Heterogeneous multi-cores utilize the strength of different architectures for executing particular types of workload, and usually offer higher performance and energy efficiency. In this paper, we study the worst-case response time (WCRT) analysis of \emph{typed} scheduling of parallel DAG tasks on heterogeneous multi-cores, where the workload of each vertex in the DAG is only allowed to execute on a particular type of cores. The only known WCRT bound for this problem is grossly pessimistic and suffers the \emph{non-self-sustainability} problem. In this paper, we propose two new WCRT bounds. The first new bound has the same time complexity as the existing bound, but is more precise and solves its \emph{non-self-sustainability} problem. The second new bound explores more detailed task graph structure information to greatly improve the precision, but is computationally more expensive. We prove that the problem of computing the second bound is strongly NP-hard if the number of types in the system is a variable, and develop an efficient algorithm which has polynomial time complexity if the number of types is a constant. Experiments with randomly generated workload show that our proposed new methods are significantly more precise than the existing bound while having good scalability.