Re: GPC speed

26 Oct 2004

      Hi, the code is short, so I think I can attach it here. It uses both dynamic 
and static arrays, but to my surprise the difference in time is slight.

--------------------------------------------------------
program arspeed;

uses GPC;

type

PMatr2Dob = ^TMatr2Dob;
TMatr2Dob (Size1, Size2: Integer) = array [ 1 .. Size1, 1..Size2 ] of double;

PVecDob = ^TVecDob;
TVecDob (Size: Integer) = array [ 1 .. Size ] of double;

const
mn = 5000;

var

matrdyn: PMatr2Dob;
vecdyn: PVecDob;

matrstat: array [ 1..mn, 1..mn ] of double;
vecstat: array [ 1..mn ] of double;

i, j, k, ntimes, itime: integer;
r1, r2, deltat, deltaperc: double;

time1, time2 : longCard;

begin

new (matrdyn, mn, mn);
new (vecdyn, mn);
ntimes := 5;

writeln ('# filling up DYNAMIC array [', mn, ', ', mn, '] with random doubles 
', ntimes, ' times.' );

time1 := GetMicroSecondTime;

for itime := 1 to ntimes do begin

	for i := 1 to mn do begin
		for j := 1 to mn do begin
			r1 := random;
			matrdyn ^[ i, j ] := r1;
		end;
	end;

end; //end itime

time2 := GetMicroSecondTime;
writeln('DYNAMIC array: total elapsed time = ', ( (time2-time1) * 
0.000001):7:2, ' seconds.' );

for i := 1 to 3 do writeln;

writeln ('# filling up STATIC array [', mn, ', ', mn, '] with random doubles 
', ntimes, ' times.' );
time1 := GetMicroSecondTime;

for itime := 1 to ntimes do begin

	for i := 1 to mn do begin
		for j := 1 to mn do begin
			r1 := random;
			matrstat [ i, j ] := r1;
		end;
	end;

end; //end itime

time2 := GetMicroSecondTime;
writeln('STATIC array: total elapsed time = ', ( (time2-time1) * 
0.000001):7:2, ' seconds.' );

for i := 1 to 3 do writeln;

ntimes := 1000;
writeln ('# filling up DYNAMIC array [', mn, '] with random doubles ', ntimes, 
' times.' );
time1 := GetMicroSecondTime;

for itime := 1 to ntimes do begin

	for i := 1 to mn do begin
		vecdyn ^[ i ] := random;
	end;

end; //end itime

time2 := GetMicroSecondTime;
writeln('DYNAMIC array: total elapsed time = ', ( (time2-time1) * 
0.000001):7:2, ' seconds.' );

for i := 1 to 3 do writeln;

writeln ('# filling up STATIC array [', mn, '] with random doubles ', ntimes, 
' times.' );
time1 := GetMicroSecondTime;

for itime := 1 to ntimes do begin
	for i := 1 to mn do begin
		vecstat [ i ] := random;
	end;
end; //end itime

time2 := GetMicroSecondTime;
writeln('STATIC array: total elapsed time = ', ( (time2-time1) * 
0.000001):7:2, ' seconds.' );

end.

--------------------------------------------------------

As for comparing with G77, I agree, this would be fairer, but I am trying to 
make my code as fast as possible, and I should choose whether to begin 
translating it into Fortran. While I like Pascal a lot better, unfortunately 
I cannot afford to lose all this amount of performance.
Thanks for your help

Silvio

| There are many reasons why GPC may be slower and many ways to speed up
| programs. Post the code (or a link if it is large) -- otherwise all
| what we can say would be pure speculation. Also, it may be usefull to
| compare GNU Fortran and Intel Fortran -- since GNU Pascal and GNU Fortran
| use the same backend, such comparison would separate effect of
| different language from differences in backends.

Re: GPC speed

Silvio a Beccara