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finished hw5

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git-svn-id: svn://anubis/gvsu@228 45c1a28c-8058-47b2-ae61-ca45b979098e
This commit is contained in:
josh 2008-11-01 17:41:12 +00:00
parent 446b8464b3
commit ec5eb17457
2 changed files with 30 additions and 8 deletions
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15
cs677/hw5/hw.tex
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@ -48,6 +48,21 @@
$$ S_G = p + (1 - p) T_s = 8 + (1 - 8) \frac{1}{24} = 7.708 $$
}
\item[5.]{
Output from instrumented Floyd program: \\
\texttt{
\$ ./floyd-sequential adjacency.dat \\
Serial execution time: 0.0248399 seconds \\
Parallel execution time: 2.01773 seconds
}
This means that the percent of sequential code is roughly 1.23\%
(for a problem size of $n = 400$).
Using Amdahl's law, the maximum speedup that can be achieved with
this program (for this problem size) is given by
$$ S_{\textrm{max}} = \frac{1}{1.23\%} = 81.25 $$
}
\end{enumerate}
\end{document}

23
cs677/hw5/src/floyd-sequential.cc
View File

@ -1,8 +1,9 @@
/* Josh Holtrop
* 2008-10-15
* 2008-11-05
* CS 677
* Grand Valley State University
* Instrumented to get serial vs. parallel run times
*/
#include <omp.h>
@ -28,6 +29,10 @@ void usage(char * progname)
int main(int argc, char * argv[])
{
struct timeval start_time, switch_time, end_time;
gettimeofday(&start_time, NULL); /* Start timing */
if (argc < 1)
usage(argv[0]);
@ -37,8 +42,7 @@ int main(int argc, char * argv[])
int D[2][num_verts][num_verts];
convertToMatrix(v, num_verts, (int *) &D[0]);
struct timeval before, after;
gettimeofday(&before, NULL); /* Start timing */
gettimeofday(&switch_time, NULL); /* Start timing */
/* Run Floyd's Algorithm on D */
for (int k = 1; k <= num_verts; k++)
@ -62,7 +66,7 @@ int main(int argc, char * argv[])
}
}
gettimeofday(&after, NULL); /* Stop timing */
gettimeofday(&end_time, NULL); /* Stop timing */
#ifdef PRINT_RESULT
cout << "Result:" << endl;
@ -80,10 +84,13 @@ int main(int argc, char * argv[])
}
#endif
double time_before = before.tv_sec + before.tv_usec / 1000000.0;
double time_after = after.tv_sec + after.tv_usec / 1000000.0;
double diff = time_after - time_before;
cout << "Elapsed time: " << diff << " seconds." << endl;
double time_start = start_time.tv_sec + start_time.tv_usec / 1000000.0;
double time_switch = switch_time.tv_sec + switch_time.tv_usec / 1000000.0;
double time_end = end_time.tv_sec + end_time.tv_usec / 1000000.0;
double serial = time_switch - time_start;
double parallel = time_end - time_switch;
cout << "Serial execution time: " << serial << " seconds" << endl;
cout << "Parallel execution time: " << parallel << " seconds" << endl;
return 0;
}