Computer organization and design  speed up things
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dukeman3

Posted: Sun Apr 03, 2016 3:01 pm Post subject: Computer organization and design  speed up things 


Consider the following recursive mergesort algorithm (another classical divide and conquer algorithm ). Mergesort was first described by John Von Neumann in 1945. The basic idea is to divide and unsorted list x of m elements into two sublists of about half size of the original list. Repeat this operation on each sublist, and continue until we have lists of size 1 in length. Then starting with sublists of length 1, “merge” the two sublists into a single sorted list.
Mergesort( m )
var list left, right, result
if length (m ) <= 1
return m
else
var middle = length (m) / 2
for each x in m up to middle
add x to left
for each x in m after middle
add x to right
left = Mergesort( left )
right = Mergesort( right )
result = Merge( left, right )
return result
The merge step is carried out by the following code:
Merge( left, right )
var list result
while length ( left ) >= 0 and length ( right ) > 0
if first ( left ) <= first ( right )
append first ( left ) to result
left = rest ( left )
else
append first ( right ) to result
right = rest (right)
if length ( left ) > 0
append rest ( left ) to result
if length ( right ) > 0
append rest ( right ) to result
return result
1.Assume that you have Y cores on a multicore processor to run Mergesort. Assuming that Y is much smaller than length ( m ), express the speedup factor you might expect to obtain for values of Y and length ( m ). Plot these on a graph
2. Next, assume that Y is equal to length (m). How would this affect your conclusions your previous answer? If you were tasked without obtaining the best speedup factor possible ( i.e. Strong scaling ), explain how you might change this code to obtain it. 





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Dan

Posted: Tue Apr 05, 2016 12:36 am Post subject: RE:Computer organization and design  speed up things 


No one here is going to do your homework for you. At least put some effort in to writing your own post rather then just copying and pasting your assignment. 
Computer Science Canada
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