Cân Bằng Tải Trong Mạng P2P Có Cấu Trúc

8/7/2019 Cn Bng Ti Trong Mng P2P C Cu Trc

1/22

Cn Bng Ti Trong Mng P2P C Cu Trc(Load Balancing in Structured P2P Networks)

Phan Anh &

Nguyn nh Ngha


2/22

01/10/2008 Phan Anh & Nguyn nh Ngha

Ni dung:

1. Mt s khi nim c bn.

2. Mt cn bng ti: Nhng nguyn nhn.3. Mt s gii php cn bng ti.


3/22


Mt s khi nim (1)

Load (Ti): ph thuc vo tng h thngP2P c th, c th l:

S bit yu cu lu tr d liu.

Bng thng mng.

Lng thi gian m CPU cn x l cng

vic


4/22


Mt s khi nim (2)

Target: ti ln nht m mt node mongmun nhn c.

Mc ch ca cn bng ti: duy tr hthng trng thi trong Load ca mtnode l nh hn Target.


5/22


6/22


Cc nh danh Node c thkhng cn bng. Do chn ID ngu nhin.

Mt cn bng ti (2)


7/22


Cc nh danh Node c thkhng cn bng.

Cc nh danh d liu cth khng cn bng.

- node- data

Mt cn bng ti (3)


8/22


britney.mp3

- node- data

tallat-song1.mp3

tallat-song2.mp3

tallat-song3.mp3

tallat-song4.mp3

Mt cn bng ti (3)



Hot spots: Cc nodes phichu ti nhiu hn cc node

bnh thng khc (b truyvn nhiu hn cc nodebnh thng khc).


9/22


- node- data



Hot spots: Cc nodes phichu ti nhiu hn cc node

bnh thng khc (b truyvn nhiu hn cc nodebnh thng khc).

Cc node ra vo mng mt

cch ty tin.

Mt cn bng ti (4)


10/22


Ni dung

Mt s khi nim c bn.

Mt cn bng ti: Nhng nguyn nhn.

Mt s gii php cn bng ti: Phng php 1: Virtual servers (servero).

Phng php 2: Khng s dng virtual servers.


11/22


Virtual Servers (VSs)

Mc tiu: S lng keys/nodecn c phn b ng u.

Nguyn tc: Mi Node vt lchn mt s lng ngu nhincc nh danh.

Mi nh danh c dnh chomt Virtual server(VS).

Mi node vt l bao gm mts lng nht nh cc VSs.

Nh vy, mi node Vt l schu trch nhim cho cc vng(regions) khng lin tip trnvng trn nh danh.

Physical Nodes Virtual Servers


12/22


13/22


Cn bng ti vi Virtual Servers (VSs)

Nguyn tc thc hin cn bng ti:

Di chuyn cc VSs t cc node vt l nngti n cc node vt l nh ti.

Vn t ra:

Gim ti a vic mt cn bng ti.

Gim ti a lng ti phi di chuyn (VSs).

Ti thiu ha cc lin kt cn duy tr.


14/22


VSs Mt s nh ngha

n s nodes trong h thng.

li ti ca ni ti mt thi im c th.

ci capacity ca ni v d: bandwidth, disk space.

i h s s dng (utilization) ca node ni.

Khi i > 1, node n b nng ti, ngc li node n c coi

l nh ti.

H s s dng ca h thng (systemutilization).

i

ii c

l!Q

!

nnodes

n

nnodesn

c

lQ


15/22


VSs Cc m hnh cn bng ti tnh

One-to-one

Mi node nh ti L nh k thi gian lin h vimt node bt k H.

Nu Hl node nng ti, virtual servers cchuyn t Hsang L Htr thnh node nh tinhng cng khng lm node L tr thnh nng ti.

L H

nh k thi gian lin h

Node ngu nhinVSs c di chuyn


16/22


One-to-many Mt th mc D c ngu nhin t ra lu thng

tin v ti ca nhng node nh ti.

Mi node nng ti Hly mt vi node nh ti tvic lin h vi D.

Mt s VSs ca Hsau c chuyn ti mt hocnhiu node nh ti ng k trong D.

L

LH

L H

D

Thng tinv ccnode nhti

Virtual servers



17/22


Many-to-many Mi th mc Dduy tr thng tin v load ca mt tp

cc node nh ti v nng ti.

Mi th mc D chy mt thut ton quyt nhvic di chuyn cc VSs t cc node nng ti ncc node nh ti.

Qu trnh c thc hin qua 3 giai on:

Unload. Insert (chn).

VSs swap (hon i VSs).



18/22


Unload

25

7 6 4

10 8 4 3

T=6, L=7

T=20, L=17

T=24, L=25

A

B

C

Pool

T=6, L=5

A

T=24, L=22


19/22


Insert (chn)

5

7 6 4

10 8 4

2

3

A

B

C

T=24, L=22

T=20, L=17

T=6, L=5

T=20, L=20

T=24, L=24

Pool


20/22


VSs M hnh lai (Hybrid scheme)

Kt hp: one-to-many v many-to-many

Mi node: nh k thi gian bo co loads v capacity ti th mc D. Nu th mc D gi vic di chuyn VSs th thc hin

iu ny.

Mi th mc Lu gi bo co ca cc nodes. nh k thi gian di chuyn cc VSs sao cho:

Ti di chuyn c ti thiu ha. Khng lm cho cc node khc tr nn nng ti.

Trng hp khn cp ti node n Nu node n tr nn nng ti, ngay lp tc yu cu th

mc di chuyn li VSs.


21/22


22/22


Tham kho

1. Chord: A Scalable Peer-to-peer Lookup Protocol forInternetApplications. Ion Stoica, Robert Morris, David Liben-Nowell, David R.Karger, M. Frans Kaashoek, Frank Dabek, Hari Balakrishnan.

IEEE/ACM Transactions on Networking (TON), 11(1):1732, 2003.2. Heterogeneity and Load Balance in Distributed Hash Tables.

P. Brighten Godfrey and Ion Stoica. INFOCOM 2004 + slides.

3. Load Balancing in Dynamic Structured P2P Systems BrightenGodfrey, Karthik Lakshminarayanan, Sonesh Surana, Richard Karp,Ion Stoica. INFOCOM 2004.

4. Simple Efficient Load Balancing Algorithms for Peer-to-PeerSystems. David R. Karger, Matthias Ruhl. 16th Annual ACMSymposium on Parallelism in Algorithms and Architectures.

Documents

Cân Bằng Tải Trong Mạng P2P Có Cấu Trúc