HELP: How to measure program execution time.

[toonski84]

http://www.betterwebber.com/test2/timwin.zip

that's the one.

[Moneo]

Oooops, Toonski, I get a "page cannot be found".
*****

[Blitz]

I think you should take my advice, in windows you can't get much higher precision then the orginal 1/18 sec.

[toonski84]

http://www.betterwebber.com/test2/TIMWIN.ZIP - sorry. damn that unix and its case insensitivity. and that works, and works only in windows.

[Antoni Gual]

Toonski:
A fine link, seav's timer does'nt work at all in W2000.
Well, I don't think my method is so bad. What are 5 seconds compared to the eternity? And for execution speed fluctuations, If you let the program loop for 5 seconds, you are averaging the execution time. It does'nt happen if you execute the test code only once.

[Blitz]

The thing with your way antoni is that you're polling on timer each loop. That's bad, even if timer was an empty function which it's not that far call alone would slow down allot. And if you're not using ffix it's horrible slowing down the loop 200%-400% i could imagine. I'm not going to repeat myself after this. But if you want accurate timing the code i posted is it.

[toonski84]

antoni, that link doesnt go to seav's timer, it goes to a library robert claypool gave me that has routines that set up a timer device with some windows interrupt. I know refreshing the timer with outs has problems in windows. you can test for dos or windows, and use the better if you were tricky.

[Moneo]

I still like Antoni's approach. It's simple, and I know exactly what's going on. If I use some fancy timing function from a library, I don't know what the heck is going on, and I have to assume it's ok.

Let's not lose sight of the issue here which is to compare two distinct blocks of code to see which is faster. Inserting these blocks of code into a loop which is incrementing a counter and which uses TIMER should not be a problem. The overhead of the counter incrementing and the invocation of TIMER is going to be applied to both blocks of code. We don't need to know exactly how fast they run --- we're only interested in which is faster.
*****

[Antoni Gual]

And if you wanted to know the exact speed you could run an empty loop and substract the time used by that loop.

[Antoni Gual]

This is the function I use to test my code speed.
In odd calls Timeit starts the timer and in even calls it returns -1 and results are printed if the test time is passed .
First couple of calls must be done in an empty loop, to calibrate the program, the results obtained will be substracted from the times of the true tests.

Code:

'this is a timing function to benchmark your routines
DECLARE FUNCTION timeit% ()


x% = -1234
'This call is to calibrate empty loop.
'Empty loop time is substracted from the real loops timer
dummy% = timeit
DO
LOOP UNTIL timeit

'--go for first test--------------------
'this starts the timer
dummy% = timeit
DO

'example of tested code
x1% = SGN(x%): x2% = ABS(x%)

'if 5 secs passed stop timer and display the results
LOOP UNTIL timeit

PRINT cubic#
'go for second test---------------------

'start the timer again
DO

'example of tested code
IF x% > 1 THEN x1% = 1: x2% = x% ELSE x1% = -1: x2% = -x%

'if 5 secs passed stop timer and display the results
LOOP UNTIL timeit

'You can add here as many test loops as you want


a$ = INPUT$(1)
END

FUNCTION timeit%
STATIC TIME!, timing%, counter!, testnum%, emptytime#
CONST testlen = 5 'seconds to loop for each test

IF timing% THEN
  IF TIMER < TIME! THEN
    counter! = counter! + 1
    EXIT FUNCTION
  ELSE
    IF testnum% = 1 THEN
        emptytime# = 1000000# / counter!
        PRINT USING "Empty loop time ###,###.### us: Loops #,###,###"; emptytime#; counter!
    ELSE
        thistime# = 1000000# / counter! - emptytime#
        PRINT USING "Test nr ## time ###,###.### us: Loops #,###,###"; testnum% - 1; thistime#; counter!
    END IF
    timing% = 0
    timeit% = -1
  END IF
ELSE
   counter! = 0
   testnum% = testnum% + 1
   timing% = NOT timing%
   PRINT
   IF testnum% > 1 THEN
    PRINT "Starting Test "; testnum% - 1; ". It will last "; testlen; " seconds."
   ELSE
    PRINT "Starting Empty loop Calibration. It will last "; testlen; " seconds."
   END IF
   TIME! = TIMER
   DO
   LOOP UNTIL TIMER > TIME!
   TIME! = TIMER + testlen
END IF

END FUNCTION