1. ICS 252 Introduction to Computer Design
Lecture 7
Winter 2004
Eli Bozorgzadeh
Computer Science Department-UCI

2. ICS 252-Intro to Computer Design
Reference
Lecture note by Rajesh Gupta on resource sharing[©Gupta]
Chapter 6.1 and 6.2 of the textbook
Administrative
Midterm 1: Feb 13, 10 a.m. in the class
Winter 2004
ICS 252-Intro to Computer Design

3. Resources in High level synthesis
Resource allocation
Determine number of resources
Resource binding
Associate a resource to each operation
Resource sharing
More than one operation bound to same resource.
Resource selection
Select appropriate type to implement each operation
[©Gupta]
Winter 2004
ICS 252-Intro to Computer Design

4. ICS 252-Intro to Computer Design
Resource allocation
Limiting cases of allocation
One resource for each operation
One resource per operation type
Determined based on implementation size constraints
Relation to scheduling
[©Gupta]
Winter 2004
ICS 252-Intro to Computer Design

5. ICS 252-Intro to Computer Design
Resource sharing
Operation compatibility
Operations that share resources
Same type
Non-concurrent
Resource compatibility graph
Resource conflict graph
Complement of compatibility graph
Winter 2004
ICS 252-Intro to Computer Design

6. ICS 252-Intro to Computer Design
Example * * + * *
< - * * - +
[©Gupta]
Winter 2004
ICS 252-Intro to Computer Design

7. ICS 252-Intro to Computer Design
Optimum solution
On conflict graph
Disjoint graph for different types
Problem of?
On compatibility graph
Problem of ?
Conflict graph is an interval graph
Hence, compatibility graph is comparability graph
Min coloring problem can be solve optimally in polynomial time in interval graphs.
Winter 2004
ICS 252-Intro to Computer Design

8. ICS 252-Intro to Computer Design
Greedy approach
Left-edge algorithm
Left-edge(I){
Lelements of I sorted in ascending order;
c=0;
While (L){
S=;
Repeat{
sfirst element in L whose left edge is higher than the rightmost edge in S;
S S U {s};
}until no more element s;
c = c +1;
Color elements of S with c;
L L-S; }
[©Gupta]
Winter 2004
ICS 252-Intro to Computer Design

9. ICS 252-Intro to Computer Design
Memory elements
Registers
Hold data across cycles
Data: value of a variable
Variable lifetime in scheduled graph
Can be re-used (shared) across variables
Memory blocks
[©Gupta]
Winter 2004
ICS 252-Intro to Computer Design

10. ICS 252-Intro to Computer Design
Register sharing
Given lifetime intervals of variables, determine minimum number of registers to store all the variables.
Standard resource sharing problem
Build register conflict/comparability graphs
Use left-edge for conflict graph
[©Gupta]
Winter 2004
ICS 252-Intro to Computer Design