An algorithm which computes very long Fibonacci numbers
http://groups.google.com/groups?selm....uni-berlin.de
was used as a performance testsuite
to compare speed of the code produced by various compilers.
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Windows 2000 Professional Ver 5.0 Build 2195 Service Pack 2
Intel(R) Celeron(R) CPU 1.70 GHz
GNU time 1.7 (to get the real time used)
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A. Real and processor time used to compute Fibonacci[10000] and Fibonacci[25000].
Here are summary results.
|================================================= ========
| | Opt | Fib-10000 | Fib-25000 |
| Compiler | Lev |-------------|-------------|
| | | Real : CPU | Real : CPU |
|================================================= =======|
| GNU gcc compiler |
|--------------------------------------------------------|
| g++ 3.3.1 (Cygwin) | No | 0.45 : 0.41 | 1.86 : 1.81 |
| | O1 | 0.28 : 0.24 | 1.03 : 0.99 |
| | O2 | 0.27 : 0.23 | 1.02 : 0.98 |
| | O3 | 0.27 : 0.24 | 1.02 : 0.98 |
| | | : | : |
| g++ 3.3.1 (Cygwin) | No | 0.33 : 0.30 | 1.59 : 1.56 |
| Mingw32 interface | O1 | 0.20 : 0.16 | 0.87 : 0.84 |
| | O2 | 0.19 : 0.16 | 0.85 : 0.82 |
| | O3 | 0.19 : 0.16 | 0.85 : 0.82 |
| | | : | : |
| gpp 3.2.1 (DJGPP) | No | 0.37 : 0.24 | 1.99 : 1.92 |
| | O1 | 0.20 : 0.11 | 1.15 : 1.05 |
| | O2 | 0.19 : 0.11 | 1.08 : 0.99 |
| | O3 | 0.19 : 0.11 | 1.08 : 0.99 |
| | | : | : |
|--------------------------------------------------------|
| Digital Mars C/C++ Compiler, STLport 4.5.3 |
|--------------------------------------------------------|
| Version 8.35n | - | 0.20 : 0.16 | 0.84 : 0.80 |
| | | : | : |
| Version 8.36.4n | - | 0.20 : 0.16 | 0.84 : 0.80 |
|================================================= ========
B. The names of DLL files on which the programs depend :
* g++ 3.3.1 (Cygwin)
------------------
C:\cygwin\bin\cygwin1.dll
C:\WINNT\System32\KERNEL32.dll
C:\WINNT\System32\NTDLL.DLL
* g++ 3.3.1 (Cygwin, Mingw32 interface)
-------------------------------------
C:\WINNT\System32\msvcrt.dll
C:\WINNT\System32\KERNEL32.dll
C:\WINNT\System32\NTDLL.DLL
* gpp 3.2.1 (DJGPP)
-----------------
Unknown
* Digital Mars C/C++ 8.35n
------------------------
C:\WINNT\System32\KERNEL32.DLL
C:\WINNT\System32\NTDLL.DLL
C:\WINNT\System32\USER32.DLL
C:\WINNT\System32\GDI32.DLL
C. Notes.
Note-1. The main() program in
http://groups.google.com/groups?selm....uni-berlin.de
was slightly changed to get the processor time used.
// ------ Updated main() : BEGIN ------
#include <time.h> // Added
int main (int argc, char **argv)
{
const string option (check (argc, argv));
if (option.empty())
{
usage (argv);
return 1;
}
const uint N = atoi (argv[2]);
const clock_t clock_start = clock(); // Added
assert (clock_start != clock_t (-1)); // Added
if (option == ALL_FIBS)
{
Fibonacci fib(N);
fib.show_all_numbers();
}
if (option == TH_FIB)
{
Fibonacci fib(N);
fib.show_last_number();
}
if (option == SOME_FIBS)
{
Fibonacci fib;
for (int i = 2; i < argc; i++) fib.show_number (atoi(argv[i]));
}
if (option == RAND_FIBS)
{
const int max_rand_fib = (argc == 3) ? MAX_RAND_FIB : atoi (argv[3]);
Fibonacci fib;
for (uint i = 0; i < N; i++) fib.show_number (rand()%max_rand_fib);
}
// ------ Added : BEGIN ------
const clock_t clock_end = clock();
assert (clock_end != clock_t (-1));
cerr << "CPU time used : " << (double (clock_end - clock_start)/CLOCKS_PER_SEC) << " sec" << endl;
// ------ Added : END --------
return 0;
}
// ------ Updated main() : END --------
Note-2. To get the real time used the time() utility was used.
D. Comment.
It seems that there is some inconsistency between real-time and CPU-time
while computing Fibonacci [10000] through the DJGPP gpp compiler :
CPU-time is too small with regard to real-time.
Probably that might be caused by too small CLOCKS_PER_SEC value (91).
Note. In Cygwin, MinGW, Digital Mars : CLOCKS_PER_SEC = 1000.
--
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Alex Vinokur
mailto:al****@connect.to
http://mathforum.org/library/view/10978.html
news://news.gmane.org/gmane.comp.lang.c++.perfometer
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