Computer Architecture Parallel The execution times of six p

Computer Architecture - Parallel

The execution times of six parallel programs, labeled I-VI, have been benchmarked on 1, 2, ..., 8 processors. The following table presents the speedups achieved by these programs. For each of these programs, choose the statement that best describes its likely performance on 16 processors with proper reasoning: The speedup achieved on 16 processors will probably be at least 40; percent higher than the speedup achieved on eight processors. The speedup achieved on 16 processors will probably be less than 40 percent higher than the speedup achieved on eight processors, due to the large serial component of the computation. The speedup achieved on 16 processors will probably be less than 40 percent higher than the speedup achieved on eight processors, due to the increase in overhead as processors are added.

Solution

let us first consider process I :
-> for 1 processor value is 1.00, when the processors are doubled ie 2, the result is 1.67.
         this means speedup of 0.67(1.67-1.00). So this makes it 67% speedup.
-> Now the processors are doubled again. ie. 4 processors, the result is 2.50
        this means speedup of 0.83 (2.50-1.67). So this makes it 49% speedup.
-> Now the processors are doubled again. ie. 8 processors, the result is 3.33
        this means speedup of 0.83 (3.33-2.50). So this makes it 33% speedup.
As, we can see the speedup percent, the percent didn\'t went two much high after doubling the processors from 1 to 2. This means that there is some part of the code which is serial that can\'t be parallelized. Therefore, the correct reason for process I is B

Now consider process II :
-> 2 processor : 89%
-> 4 processor : 70%
-> 8 processor: 34%
since the percent will be less than 40% and the reason is due to the increase in overhead as processors are added. Therefore, the correct reason for process II is C.

Now consider process III :
-> 2 processor : 89%
-> 4 processor : 79%
-> 8 processor: 66%
since the percent will be atleast 40% .Therefore, the correct reason for process III is A.

Now consider process IV :
-> 2 processor : 96%
-> 4 processor : 87%
-> 8 processor: 70%
since the percent will be atleast 40% .Therefore, the correct reason for process IV is A.

Now consider process V :
-> 2 processor : 74%
-> 4 processor : 57%
-> 8 processor: 39%
since the percent will be less than 40% and the reason is due to the increase in overhead as processors are added. Therefore, the correct reason for process II is C.

Now consider process VI :
-> 2 processor : 94%
-> 4 processor : 88%
-> 8 processor: 78%
since the percent will be atleast 40% .Therefore, the correct reason for process VI is A.