What have we seen in class recently?

Daniel Shapiro

• Exec time = (Task Crunch Amount)/(speed of PE)

• Makespan (longest critical path)• Adjacent communication delay(i,j) = (Data

amount)/(transfer rate between PEs)• in-forest: each node has at most one immediate successor• out-forest: each node has at most one immediate

predecessor

Time

• Completion Time = Execution Time + Total Communication Delay

• Total Communication Delay = Number of communication messages * delay per message

• Execution time maximum finishing time of any task

4

Scheduling inforest/outforest task graphs

1. The level of each node in the task graph is calculated as given above and used as each node’s priority

2. Whenever a processor becomes available, assign it the unexecuted ready task with the highest priority

5

Example

10

14 13

12

11

9

8 7

5

6

4

2

3

1

P1 P2 P3

1

2 3 4

5 6 7

8 9 10 11 12

13 14 Level 5

Level 4

Level 3

Level 2

Level 11

1 1 1

1 1 1

1 1 1 1 1

1 1

6

Scheduling interval ordered tasks

1. The number of successors of each node is used as each node’s priority

2. Whenever a processor becomes available, assign it the unexecuted ready task with the highest priority

7

Example

0 0 0

3 2 1

4 5 61

9

1 1

1 1 1

1 1 1

1 2 3

654

7 8

Time P1 P2

123

4 5 6

87 9

P30

1

2

3

8

a

b c

a

b

c

a

b

c

c

P1 P2 P1 P2

10

25

0

10

25

0

40

15

35c

40

50

x

x

x

Task Graph

Gantt Chart-2Gantt Chart-1

Task Exceution time

abc

101515

y

Arc Communication

(a,b) y

(a,c) x < y

x = 5 x = 25

30

Time Time

Communication Delay versus Parallelism

9

Clustering

a

bc

g

d e

f

a

bc

g

d e

f

a

bc

g

d e

f

(a)(b)

(c)

a

bc

g

d e

f

(d)

10

a

b c

a

b c

a

b

c

P1 P2 P1 P2

xx

Task Graph

x

a

No Duplication Task a is Duplicated

Duplications

Real Stuff

• http://www.site.uottawa.ca/eng/school/publications/techrep/2010/

Where is my T.A.?http://www.eng.tau.ac.il/~ieee/Convention/index.html

Instruction Set Extensions for Computation on Complex Floating Point Numbers

Parallel instruction set extension identification

Questions?

• Danke