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IBM Thomas J. Watson Research Center © 2004 IBM Corporation Analysis of Parallel- Server Systems with Dynamic Affinity Scheduling and Load Balancing Mark S. Squillante Mathematical Sciences Department April 18, 2004

Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

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Mark S. Squillante Mathematical Sciences Department April 18, 2004. Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing. Problem Motivation. Cache Affinity [SquillanteLazowska90]. Problem Motivation. Cache Affinity [SquillanteLazowska90]. - PowerPoint PPT Presentation

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Page 1: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

IBM Thomas J. Watson Research Center

© 2004 IBM Corporation

Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

Mark S. SquillanteMathematical Sciences DepartmentApril 18, 2004

Page 2: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

2

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Problem Motivation

Cache Affinity [SquillanteLazowska90]

Page 3: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

3

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Problem Motivation

Key Points of Fundamental Tradeoff Customers can be served on any server of a parallel-server queueing system Each customer is served most efficiently on one the servers Load imbalance among queues occurs due to stochastic properties of system

Cache Affinity [SquillanteLazowska90]

Page 4: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

4

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

General Overview

Optimal Dynamic Threshold Scheduling Policy– Fluid limits

– Diffusion limits

Analysis of Dynamic Threshold Scheduling– Consider generalized threshold scheduling policy

– Matrix-analytic analysis and fix-point solution, asymptotically exact

– Numerical experiments

– Optimal settings of dynamic scheduling policy thresholds

Stochastic Derivative-Free Optimization

Page 5: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

5

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Scheduling Policy

()

()

1

P

Page 6: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

6

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Scheduling Model

()

()1

P

()

Page 7: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

7

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

Ts

u,1,0

Tsu,0,0

Tsu+1,0,1

Tsu+1,0,0

r r

(1-ps)

(1-ps)

r r

s

0,1,0

0,0,0

1,0,1

1,0,0

(1-pr)

(1-pr)pr

pr

……

Tru,1,0

Tru,0,0

Tru+1,0,1

Tru+1,0,0

r

r

……

……

State Vector ( i, j, v ):

• i: total number of customers waiting or receiving service at the processor of interest

• j: number of customers in the process of being migrated to the processor of interest

• v: K-bit vector denoting customer type of up to the first K customers at the processor

Page 8: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

8

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

Ts

u,1,0

Tsu,0,0

Tsu+1,0,1

Tsu+1,0,0

r r

(1-ps)

(1-ps)

r r

s

0,1,0

0,0,0

1,0,1

1,0,0

(1-pr)

(1-pr)pr

pr

……

Tru,1,0

Tru,0,0

Tru+1,0,1

Tru+1,0,0

r

r

……

……

Page 9: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

9

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

Ts

u,1,0

Tsu,0,0

Tsu+1,0,1

Tsu+1,0,0

r r

(1-ps)

(1-ps)

r r

s

0,1,0

0,0,0

1,0,1

1,0,0

(1-pr)

(1-pr)pr

pr

……

Tru,1,0

Tru,0,0

Tru+1,0,1

Tru+1,0,0

r

r

……

……

Page 10: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

10

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

Ts

u,1,0

Tsu,0,0

Tsu+1,0,1

Tsu+1,0,0

r r

(1-ps)

(1-ps)

r r

s

0,1,0

0,0,0

1,0,1

1,0,0

(1-pr)

(1-pr)pr

pr

……

Tru,1,0

Tru,0,0

Tru+1,0,1

Tru+1,0,0

r

r

……

……

Page 11: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

11

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

Ts

u,1,0

Tsu,0,0

Tsu+1,0,1

Tsu+1,0,0

r r

(1-ps)

(1-ps)

r r

s

0,1,0

0,0,0

1,0,1

1,0,0

(1-pr)

(1-pr)pr

pr

……

Tru,1,0

Tru,0,0

Tru+1,0,1

Tru+1,0,0

r

r

……

……

Page 12: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

12

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

Ts

u,1,0

Tsu,0,0

Tsu+1,0,1

Tsu+1,0,0

r r

(1-ps)

(1-ps)

r r

s

0,1,0

0,0,0

1,0,1

1,0,0

(1-pr)

(1-pr)pr

pr

……

Tru,1,0

Tru,0,0

Tru+1,0,1

Tru+1,0,0

r

r

……

……

Page 13: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

13

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

Ts

u,1,0

Tsu,0,0

Tsu+1,0,1

Tsu+1,0,0

r r

(1-ps)

(1-ps)

r r

s

0,1,0

0,0,0

1,0,1

1,0,0

(1-pr)

(1-pr)pr

pr

……

Tru,1,0

Tru,0,0

Tru+1,0,1

Tru+1,0,0

r

r

……

……

Final Solution Obtained via Fix-Point Iteration

1. Initialize (ps, s, pr, r)

2. Compute stationary probability vector in terms of (ps, s, pr, r)

3. Compute new values of (ps, s, pr, r) in terms of stationary vector

4. Goto 2 until differences between iteration values are arbitrarily small

Page 14: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

14

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

Ts

u,1,0

Tsu,0,0

Tsu+1,0,1

Tsu+1,0,0

r r

(1-ps)

(1-ps)

r r

s

0,1,0

0,0,0

1,0,1

1,0,0

(1-pr)

(1-pr)pr

pr

……

Tru,1,0

Tru,0,0

Tru+1,0,1

Tru+1,0,0

r

r

……

……

Page 15: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

15

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

Ts

u,1,0

Tsu,0,0

Tsu+1,0,1

Tsu+1,0,0

r r

(1-ps)

(1-ps)

r r

s

0,1,0

0,0,0

1,0,1

1,0,0

(1-pr)

(1-pr)pr

pr

……

Tru,1,0

Tru,0,0

Tru+1,0,1

Tru+1,0,0

r

r

……

……

Page 16: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

16

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

General K, Pure Sender-Initiated Policy

Page 17: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

17

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

General K

Page 18: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

18

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Mathematical Analysis

General K

Page 19: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

19

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Numerical Results

Page 20: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

20

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Numerical Results

Page 21: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

21

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Numerical Results

Page 22: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

22

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Numerical Results

Page 23: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

23

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Numerical Results

Page 24: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

24

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

Stochastic Derivative-Free Optimization

Internal Model

External Model

Trust Region

Page 25: Analysis of Parallel-Server Systems with Dynamic Affinity Scheduling and Load Balancing

25

IBM Thomas J. Watson Research Center

© 2004 IBM CorporationAnalysis of Dynamic Affinity Scheduling and Load Balancing | Mark S. Squillante

General Overview

Optimal Dynamic Threshold Scheduling Policy– Fluid limits

– Diffusion limits

Analysis of Dynamic Threshold Scheduling– Consider generalized threshold scheduling policy

– Matrix-analytic analysis and fix-point solution, asymptotically exact

– Numerical experiments

– Optimal settings of dynamic scheduling policy thresholds

Stochastic Derivative-Free Optimization