GPU schedulers: How fair is fair enough?
File(s)
Published version
Author(s)
Sorensen, T
Evrard, H
Donaldson, AF
Type
Conference Paper
Abstract
Blocking synchronisation idioms, e.g. mutexes and barriers, play an important role in concurrent programming. However, systems with semi-fair schedulers, e.g. graphics processing units (GPUs), are becoming increasingly common. Such schedulers provide varying degrees of fairness, guaranteeing enough to allow some, but not all, blocking idioms. While a number of applications that use blocking idioms do run on today’s GPUs, reasoning about liveness properties of such applications is di cult as documentation is scarce and scattered. In this work, we aim to clarify fairness properties of semi-fair schedulers. To do this, we define a general temporal logic formula, based on weak fairness, parameterised by a predicate that enables fairness per-thread at certain points of an execution. We then define fairness properties for three GPU schedulers: HSA, OpenCL, and occupancy-bound execution. We examine existing GPU applications and show that none of the above schedulers are strong enough to provide the fairness properties required by these applications. It hence appears that existing GPU scheduler descriptions do not entirely capture the fairness properties that are provided on current GPUs. Thus, we present two new schedulers that aim to support existing GPU applications. We analyse the behaviour of common blocking idioms under each scheduler and show that one of our new schedulers allows a more natural implementation of a GPU protocol.
Date Issued
2018-09-04
Date Acceptance
2018-06-16
Citation
Leibniz International Proceedings in Informatics, LIPIcs, 2018, 118
ISBN
9783959770873
ISSN
1868-8969
Publisher
Schloss Dagstuhl - Leibniz-Zentrum für Informatik
Journal / Book Title
Leibniz International Proceedings in Informatics, LIPIcs
Volume
118
Copyright Statement
© Tyler Sorensen, Hugues Evrard, and Alastair F. Donaldson;
licensed under Creative Commons License CC-BY (https://creativecommons.org/licenses/by/3.0/).
licensed under Creative Commons License CC-BY (https://creativecommons.org/licenses/by/3.0/).
Sponsor
Engineering & Physical Science Research Council (E
Grant Number
542716
Source
29th International Conference on Concurrency Theory (CONCUR 2018)
Publication Status
Published
Start Date
2018-09-04
Finish Date
2018-09-07
Coverage Spatial
Beijing, China
Date Publish Online
2018-09-04