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006,

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Perfo

rman

ce co

mpari

son be

twee

n a 2

phase

s and

a 3 p

hases

Nego

tiatio

n pro

tocol

Antoi

ne Pi

chot,

Aleja

ndro

Gaspa

rAp

ril, 2

007

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2| Pe

rf comp

betw

een a

2 Phase

s and a

3 Phases

Negotia

tion P

rotocol

| Apri

l 2007

Agenda

1. Pr

oblem

2. Mo

del

3. Re

sults

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s and a

3 Phases

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tion P

rotocol

| Apri

l 2007

The P

roblem

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rf comp

betw

een a

2 Phase

s and a

3 Phases

Negotia

tion P

rotocol

| Apri

l 2007

The context : Co-allocation

Multiple Computing farms

A (G)MPLS network

How to reserve two (or m

ore) reso

urces at

the same time ?

I.e. : A network connexion & a CPU

TORI

NO

GENO

VA

ALES

SAND

RIA PI

SA

MIL

ANO MIL

ANO2

BRES

CIA

SAVO

NA

BOLO

GNA

VERO

NAVICE

NZA VE

NEZI

A

FIREN

ZE

PERU

GIAAN

CONA

PESC

ARA

L’AQ

UILA

ROM

A

ROM

A2

NAPO

LISA

LERN

O

CATA

NZAR

O

POTE

NZA

BARI TA

RANT

O

CAGL

IARI

SASS

ARI

PALE

RMO

MES

SINA

REGG

IO C

.

CPUs

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3 Phases

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| Apri

l 2007

Solutions

•VIO

LA like (2Phases comm

it protocol)

•WS-Agreement based

Negotiation (3Phases Comm

it Protocol)

•Cf O.Waeldrich&

W. Ziegler draft @OGF18

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| Apri

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3 Phases Comm

it Protocol vs 2 Phases

•Capability and availability check

•Pre

-reservation

•Resou

rce are rese

rved w

ith short reservation lifetim

e•

(No p

enalt

ies if

reserv

ation

is ca

ncell

ed at

this

stage

)

•Comm

itment

•Re

source

are r

eserve

d whe

never

need

ed•

(pena

lties

if can

celle

d)

Phase

2

Phase

1

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3 Phases

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| Apri

l 2007

VIOLA architecture

Aka A

RGON

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VIOLA reservation process

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3 Phases

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VIOLA’s Meta-Scheduler reservation

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| Apri

l 2007

The M

odel

Expla

ined

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3 Phases

Negotia

tion P

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| Apri

l 2007

Model origin

Gurba

niV.K

.,Jag

adee

sanL.,

Mend

iratta

V.B.,

“Cha

racter

izing s

ession

initia

tion p

rotoc

ol (SI

P) ne

twork

perfo

rman

ce an

d rel

iability”,

Intern

ation

al ser

vice a

vaila

bility

sympo

sium,

April

2005

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3 Phases

Negotia

tion P

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| Apri

l 2007

Model explained(1)

Job requests �

Clients of the

queuing network

Time spent in a w

aiting queue �

Time spent in a state i

nsidethe

MS

A queue �

A state i

nsidethe

MS

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| Apri

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Model Explained (2), Notation convention

Meta-

Sche

duler

Crea

teAgre

emen

tµ 1

1/µ1is

the a

verag

e tim

e tak

en by

the M

eta-Sc

hedu

ler to

�re

ceive

the C

reate

Agre

emen

t mes

sage,

�pro

cess

it, an

d �ta

ke ac

tion

A Loc

al Sc

hedu

ler

Subm

itµ 2

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| Apri

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Model Explained (3), Example

Example synchronous

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2 Phases Negotiation protocol Model

Asynchronous

Synchronous

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3 Phases Negotiation protocol Model

Asynchronous

Synchronous

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3 Phases

Negotia

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| Apri

l 2007

Service Time & Error Probability example

After a few measures on a P4@2.8G

Hz

o��

�����

���

����

���…………………………………………………

���

o��

�����

� �

�����

������………………………………………………………

�����

��

o��

� ����

����

���……………………………………………………………

�����

��

�����

��

Probability to cancel a rese

rvation : 10%

Probability to need to look after scheduling horizon : 10%

Those

values can be modifie

d to take m

ore realistic values.

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3 Phases

Negotia

tion P

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| Apri

l 2007

Limiting Queue

)))(

((

1/2

2CB

AM

Qµ+

+−

=λ

ρ

For example (3 Phases Asynchronous) :

Arriv

al rat

e

Servi

ce ra

te

Prob

abilit

y to l

oop o

r to g

et an

erro

r

=−

=

Queues

Nb

kk

kN

11ρρ

Load

of

Queu

e k

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| Apri

l 2007

Resul

ts

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3 Phases

Negotia

tion P

rotocol

| Apri

l 2007

Maxim

um Job request Arrival Rate in the

Meta-Scheduler Alm

ost N

O IMPA

CT on

Arriv

al Rate

NEED

for

ASYN

CHRO

NOUS

Imple

mentati

on

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| Apri

l 2007

Mean number of Jobs in the

Meta-Scheduler

Threshold

2 Ph

ases

Threshold

3 Ph

ases

Synchronous

Asynchronous

Perfo

rmance loss

of 3P

NP ov

er 2P

NP

Less than 50

%

xPNP

: x Ph

ases N

egoti

ation

Proto

col

Arriv

al Rate

= 63 j

ob/s

Delay

~ 240m

s

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Conclusions

Need for an Asynchronous implem

entation (obvious)

Performance loss of a 3 Phases over a 2 Phases Negotiation protocol is

�less than 10% on the m

aximum job request arrival rate

�less than 50% on the total jo

b request processing delay and m

emory

requirement

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| Apri

l 2007

References

Article to be publishe

d soon…

by the end of the year

For a similar model use

d in a different context :

Gurba

niV.K

.,Jag

adee

sanL.,

Mend

iratta

V.B., “

Chara

cteriz

ing se

ssion

initia

tion

protoc

ol (SI

P) ne

twork

perfo

rman

ce an

d relia

bility”

, Inter

natio

nal se

rvice

avail

abilit

y sym

posiu

m, Ap

ril 20

05

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3 Phases

Negotia

tion P

rotocol

| Apri

l 2007

antoi

ne.pi

chot@

alcate

l-luce

nt.fr