1. Amdahl’s Law – Who, What, When, Where, Why - - and How !!
CDA 3101 – Spring 2016 – Review for Quiz 5
Contents:
What is Amdahl’s Law? Who was Gene Amdahl?
What Kinds of Problems Do We Solve With Amdahl’s Law?
How Do We Solve These Amdahl’s Law Problems?
USE UP AND DOWN ARROW KEYS TO NAVIGATE ANIMATIONS

2. Why Do We Use Amdahl’s Law? ESTIMATE SYSTEM PERFORMANCE for…
What is Amdahl’s Law?
Amdahl's law is an expression used to find the maximum expected improvement S to an overall system when only part of the system (fE) is improved by a factor fI. Amdahl’s Law is often used in parallel computing to predict the theoretical maximum speedup using multiple processors. ( )
Why Do We Use Amdahl’s Law?
ESTIMATE SYSTEM PERFORMANCE for…
Performance Improvement Problems!!

3. Who Was Gene Amdahl?
Gene Myron Amdahl (November 16, 1922 – November 10, 2015) was an American computer architect and high-tech entrepreneur, chiefly known for his work on mainframe computers at IBM and later his own companies, especially Amdahl Corporation. He formulated Amdahl's Law…
( )

4. Time T for part of system that can’t be improved
What Kinds of Problems Do We Solve With Amdahl’s Law?
Performance Improvement Problems!!
Entire System
Part of System That Can’t Be Improved Part That Can Be Improved
Time T for part of system that can’t be improved fE
IMPROVEMENT
Time TE for fE with improvement
Time TO for fE without improvement
System Speedup S = 𝑇+ 𝑇 𝑂 𝑇+ 𝑇 𝐸
fI = TO / TE

5. How Do We Solve Amdahl’s Law Problems?
Amdahl’s Law Equation:
Divide Problem Space Into Three Cases:
Given: fE and fI Find: S
Given: S and fE Find: fI
Given: S and fI Find: fE
(S)
(fE)
(fE)
(fI)

6. How Do We Solve Amdahl’s Law Problems?
Case 1: Given: fE and fI Find: S

7. How Do We Solve Amdahl’s Law Problems?
Case 2: Given: S and fE Find: fI
Oops, that one didn’t work so well … let’s try another example

8. How Do We Solve Amdahl’s Law Problems?
Case 2: Given: S and fE Find: fI

9. How Do We Solve Amdahl’s Law Problems?
Case 3: Given: S and fI Find: fE

10. That’s All There Is To It!!
Have Fun Surfing with Amdahl’s Law!!