Performance Evaluation of a SNAP-based Community Resource Broker

Mohammed H. Haji, Peter Dew, Karim Djemame and Iain Gourlay

Outline

DAME Project (Distributed Aircraft Maintenance Environment)

Current challenges within Grid middleware

Grid Resource Brokers

Service Negotiation Acquisition Protocol

Use of a Knowledge bank

Three-phase Commit protocol

Performance results

Conclusion and future work

DAME Project (Distributed Aircraft Maintenance Environment)

DAME is a joint project Four Universities, Leeds, York,

Sheffield and Oxford Industrial partners are Rolls Royce,

Data Systems and Solutions and Cybula Ltd

This project aims to build a distributed diagnostics decision support system, for the use of Virtual Organisations (VOs), based on Grid technology

Current Challenges within Grid Middleware

There are many complexities in-order to submit a simple Grid job:

Have the ability to query local and remote resource Information Providers

Identify and filter out the appropriate resources for the job

Co-allocate the job

Secure the resources

Submit the job

Monitor and police the active job

Grid Resource Brokers

A Resource Broker is a middleware entity that

insulates the user from the Grid complexities

Two broad categories of resource brokers: System-centric which enhances system

utilisation and throughput User-centric which enhances computation

and adheres to user requirements

Service Negotiation and Acquisition Protocol (SNAP)

Observation

User requirements through a Grid portal

Resources

QoS needs Policies

Feedback on decisions

made

ResourceavailabilityResources

Active Job

SLA

Resource query/ Dispatch

Monitor Policing

Resource broker

TSLA

RSLA

BSLA

Task Service Level Agreement (TSLA).

Resource Service Level Agreement (RSAL).

Binding service level agreement (BSLA).

User requirements through a Grid portal

Task Service Level Agreement (TSLA)

Resource broker

Resource Service Level Agreement (RSLA)

Resources

Resources

Active Job

SLAMonitor

Binding Service Level Agreement (BSLA)

SNAP Development

Resources

Knowledgebank

Matchmaker

Co-ordinator

DispatcherResource gatherer

Decision maker

Grid middleware

R R R R

PortalPortalTSLA

RSLA

BSLA

Knowledge Bank (KB)

Benefits of having a KB:

Facilitate the broker in supporting automated resource discovery

Alleviate the user from the burden of keeping a log of the resources

Enhance efficiency by avoiding unnecessary interaction with resources

The KB stores a history profile of past performance of resources enables the broker to differentiate and categorise the resources into different levels

An analogy to the KB is a telephone directory

Resources

Knowledgebank

Matchmaker

Co-ordinator

DispatcherResource gatherer

Decision maker

Grid middleware

R R R R

PortalPortalTSLA

RSLA

BSLA

Need to Secure Resources

Three-Phase Commit Protocol

First phase Contact the categorised resources which would either be tagged as white or blue

Second phase On receiving the information from all the contacted resources, the broker co-allocates the task The selected resources are reserved and evolve into the amber state The data is transferred

Third phase The information service updates the resource status to red and the job is bound to the resources and begins execution

Establish a socket connection for probing the dynamic information and keeping a vision of any resource status change

Blue tagged

resources

White tagged

resources

Resources in the amber

state

Resources in the red

state

Experimental Design and Performance Evaluation

Objectives Investigate behaviour of both a simple SNAP broker and one using the

three-phase commit protocol Performance evaluation

Scenario 1 Resources appropriate for the job are taken and the broker must wait

until they become free before submitting the jobCase A The information provider response time varies but the job duration is constant

Case B The information provider response time is constant but the job duration

is varied

Scenario 2 While the broker is in the process of making a decision as to where

the job should be submitted the resources are taken

Results: Scenario 1 Case A Experiment 1

0

20

40

60

80

100120

140

160

180

200

10 20 30 40 50 60 70 80 90

Information provider response time (Sec)

Tim

e w

he

n t

he

bro

ke

r k

ne

w t

he

re

so

urc

es

we

re f

ree

d (

Se

c) Simple SNAP Broker

Three-phase commit SNAP Broker

0

40

80

120

160

200

240

280

320

360

10 20 30 40 50 60 70 80 90

Information provider response time (Sec)

Ave

rag

e jo

b e

xecu

tio

n s

tart

tim

e (S

ec)

Simple SNAP Broker

Three-phase commit SNAP broker

Results: Scenario 1 Case A Experiment 2

0

20

40

60

80

100

120

140

30 40 50 60 70 80 90 100 110

Time when resources were freed (Sec)

Th

e ti

me

wh

en t

he

bro

ker

knew

th

e re

sou

rces

wer

e fr

eed

(S

ec)

Simple SNAP Broker

Three-phase commit SNAP Broker

Results: Scenario 1 Case B Experiment 1

0

20

40

60

80

100

120

140

160

180

200

30 40 50 60 70 80 90 100 110

Time when the resources were freed (Sec)

Ave

rag

e jo

b e

xecu

tio

n s

tart

tim

e (S

ec)

Simple SNAP Broker

Three-phase commit SNAP Broker

Results: Scenario 1 Case B Experiment 2

0

20

40

60

80

100

120

140

160

180

0 1 2 3 4 5 6 7

Number of resources taken

Av

era

ge

job

ex

ec

uti

on

sta

rt t

ime

(S

ec

)

Simple SNAP Broker

Three-phase commit SNAP Broker

Results: Scenario 2 Experiment

Future Work

To deploy the SNAP-based resource broker on the White Rose Grid (WRG) using the Three-phase commit protocol.

SNAP-based resource broker is a viable contender for use in future Grid implementations.Results indicate that in certain specific scenarios, three-phase commit protocol provides a performance enhancement over a simple SNAP-based broker. Further work would be to investigate the broker in a wider scenario space through mathematical modelling and simulation and for it to be deployed on the WRG.

Conclusion

References

M.H. Haji, P.M. Dew, K. Djemame, I. Gourlay. A SNAP-based Community Resource Broker using a Three-Phase Commit Protocol, 18th IEEE International Parallel and Distributed Processing Symposium, Santa Fe, New Mexico, April 2004.

K. Djemame, M.H Haji, J. Padgett. SLA Management in a Service Oriented Architecture, 2004 International Conference on Computational Science and its Application, Assisi, Italy , May 2004.

A. Othman, P. Dew, K. Djemame, I. Gourlay Adaptive Grid Resource Brokering, IEEE Cluster Computing, December 2003, Hong Kong.