Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
A Utilization-based Schedulability Test of Real-time Systems Running on a Multiprocessor Virtual Machine
Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
(English)In: The Computer JournalArticle in journal (Refereed) Submitted
Abstract [en]

Virtualization  makes it possible  to  run  multiple  operating  systems  and  applications  on  the  same  physical  hardware  at  the same timeusing Virtual Machines (VMs). Real-time applications with hard deadlineswould also like tobenefit from using VMs. The underlying physical infrastructure usually contains many cores.  In this paper, we consider a hard real-time applicationthat executeson a VM with multiple virtual cores. Tasks are scheduled globally on the multiprocessor VMusing fixed-priority preemptive scheduling. This means that a task can execute on different virtual coresat different instances in time. In order to avoid Dhall’s effect, which may cause task sets with even very low utilization to miss deadlines, we classify tasks into two priority classes, namely heavy and light tasks. Heavy tasks have higher priority than light tasks. For light tasks we use rate monotonic priority assignment. In this paper we propose a utilization-based test that shows if a task set is schedulable or not. If the task set is schedulable, the test also provides an assignment of priorities to tasks. The input to the test is the taskset, the number of cores (processors)in the VM, the period for the multiprocessor VM,the VM’s deadline, the execution time, and the blocking time when theVMdoes not have access to the underlying hardware in each  period.This  work  generalizes  previous  workby  introducing the  VM’sdeadline as  a  parameter.  We  validate  our  study  by simulation, the results show that the priority assignment used by our algorithm scheduleshigher number of task setsthanthose using rate monotonic (RM)priority assignment.

Keywords [en]
Hard real-time scheduling; Real-time system; Multiprocessor utilization based schedulability test; Virtual multiprocessorscheduling; Global fixed priority scheduling, VM deadline
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:bth-15756OAI: oai:DiVA.org:bth-15756DiVA, id: diva2:1173847
Funder
Knowledge Foundation, 20140032Available from: 2018-01-14 Created: 2018-01-14 Last updated: 2018-01-19Bibliographically approved
In thesis
1. Performance Aspects of Databases and Virtualized Real-time Applications
Open this publication in new window or tab >>Performance Aspects of Databases and Virtualized Real-time Applications
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Context: High computing system performance depends on the interaction between software and hardware layers in modern computer systems. Two strong trends that effect different layers in computer systems are that single processors are now more or less completely replaced by multiprocessors, which are often organized into clusters, and virtualization of resources. The performance evaluation of different software on such physical and virtualized resources, is the focus of this thesis.

Objectives: The objectives of this thesis are to investigate the performance evaluation of SQL and No SQL database management systems, namely Cassandra, CouchDB, MongoDB, PostgreSQL, and RethinkDB; and soft real-time application namely, voice-driven web. Scheduling algorithms for resource allocation for hard real-time applications on virtual processor are also investigated.

Methods: Experiment is used to measure the performance of SQL and No SQL management systems on cluster. It is also used to develop a prototype and predicts processor performance of voice-driven web on multiprocessors. Theoretical methods are used to model and design algorithms to schedule real-time applications on the virtual processor machine. Simulation is used to quantify the performance implications of certain parameter values in our theoretical results and to compare expected performance with theoretical bounds in our schedulability tests.

Results:The performance of Cassandra, CouchDB, MongoDB, 2

PostgreSQL, and RethinkDB is evaluated in terms of writing and reading throughput and latencies in cluster computing. For reading throughput, all database systems are horizontally scalable as the cluster’s nodes number increases, however, only Cassandra and couchDB exhibit scalability for data writing. The overall evaluation shows that Cassandra has the most writing scalable throughput as the number of nodes increases with a relative low latency, whereas PostgreSQL has the lowest writing latency, and MongoDB has the lowest reading latency.

The architectures’ tradeoffs of voice-driven web show that the voice engine should be installed on the server instead of being on the mobile device, and performance evaluations show that speech engine scales with respect to the number of cores in the multiprocessor with and without hyperthreading.

The thesis presents scheduling techniques for real-time applications that runs in virtual machines which are time sharing the processor. Each virtual machine’s period and execution time that allow real-time applications to meet their deadlines can be defined using these techniques. Simulation results show the impact of the length of different VM periods with respect to overhead. The tradeoffs between resources consumption and period length are also given. Furthermore, a utilization based test for scheduling real-time application on virtual multiprocessor is presented. This test determines if a task set is schedulable or not. If the task set is schedulable the algorithm provides the priority for each task. This algorithm avoids Dhall’s effect, which may cause task sets with even very low utilization to miss deadlines.

Conclusions: The thesis presented the performance evaluation of reading and writing throughput and latencies for SLQ and NoSQL management systems in the cluster computing. The thesis quantifies the tradeoffs of voice-driven web architectures and the performance scalability of the speech engine with respect to number of cores of the multiprocessor. Furthermore, this thesis proposes scheduling algorithms for real-time 3

application with hard deadline on virtual processors, either as a single core processor or as a multicore processor.

Place, publisher, year, edition, pages
Karlskrona: Blekinge Tekniska Högskola, 2018. p. 36
Series
Blekinge Institute of Technology Doctoral Dissertation Series, ISSN 1653-2090 ; 02
Keywords
SLQ and NoSQL database, Bigdata management systems, Structured and non-structured Database Evaluation, Voice-driven web, Multicore performance prediction, Hard real-time Scheduling, Virtual Multiprocessor Scheduling
National Category
Computer Sciences
Identifiers
urn:nbn:se:bth-15758 (URN)978-91-7295-348-2 (ISBN)
Public defence
2018-09-21, J1650, Blekinge Tekniska Högskola, 371 79 Karlskrona, Karlskrona, 13:00 (English)
Opponent
Supervisors
Funder
Sida - Swedish International Development Cooperation Agency
Available from: 2018-01-15 Created: 2018-01-14 Last updated: 2018-06-07Bibliographically approved

Open Access in DiVA

No full text in DiVA

By organisation
Department of Computer Science and EngineeringDepartment of Mathematics and Natural Sciences
Electrical Engineering, Electronic Engineering, Information Engineering

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 37 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf