Print to screen

[alphagemini]

I run a maths program on an Amiga 4000/040 involving repetitive outputs printed to screen. The data produced are stored on hard disk. Would the print to screen process slow the calculations? If this display was omitted would the maths coprocessor work more quickly?

Thanks for any response.

[thomas]

Surely console output slows down the processing. In fact nothing decelerates a program more than a scrolling Shell window, especially if you don't have a graphics card.

There is already a huge speed difference if you redirect console output into a file.

Removing the output altogether gains another lot of speed.

It depends however on the amount of output produced. If you only print "200 of 1000 done" every second or so, there is almost no slowdown.

But a "for i=1 to 1000000: print i: next" is a lot slower than the same loop without print.

[alphagemini]

Thanks for the help. I have tried to clock the speed with and without screen print but can't see any difference. I will try again. One cycle takes about 4 seconds so its difficult simply using a counter to check properly.

Thanks again

[daxb]

I don`t know where is the boarder where you notice speed differences but 4 sec. for one cycle shouldn`t slow down calculation if every 4 sec. a print to screen is done.

[thomas]

Like I said, it depends on the amount of output. If there are seconds between two lines, then no difference will be seen. But if you print 1000 messages per second, the difference will be huge.

Take this Rexx script:

/* rexx */

x = time('R')

do verbose = 4 to 0 by -1

   do i=0 to 9
      if verbose >= 1 then say "i =" i
      do j=0 to 9
         if verbose >= 2 then say "i =" i"; j =" j
         do k=0 to 9
            if verbose >= 3 then say "i =" i"; j =" j"; k =" k
            do l=0 to 9
               if verbose >= 4 then say "i =" i"; j =" j"; k =" k"; l =" l
            end
         end
      end
   end

   say "verbose =" verbose"; elapsed time:" time('R')

end

With verbose = 4 it prints 10,000 lines and needs 12.52 seconds. On WinUAE with gfx card. Probably much longer on a real Amiga and/or with native display.

verbose = 3 prints only 1,000 lines and is already much faster: 1.5 seconds.
verbose = 2 -> 100 lines -> 0.22 seconds
verbose = 1 -> 10 lines -> 0.1 seonds
verbose = 0 -> no output -> 0.08 seconds

The same script run with redirection to a file in RAM shows the huge overhead of console output:

verbose = 4 -> 0.52 seconds
verbose = 3 -> 0.12 seconds
verbose = 2, 1, 0 -> 0.08 seconds

[daxb]

Results for my A1200 040/40 AGA OS3.1 if someone wants to compare:

To KingCON Shell:

verbose = 4; elapsed time: 289.66
verbose = 3; elapsed time: 30.76
verbose = 2; elapsed time: 5.18
verbose = 1; elapsed time: 2.62
verbose = 0; elapsed time: 2.36

Redirect to RAM:

verbose = 4; elapsed time: 11.88
verbose = 3; elapsed time: 3.20
verbose = 2; elapsed time: 2.42
verbose = 1; elapsed time: 2.30
verbose = 0; elapsed time: 2.32