[Xenomai-help] Timing calculation

["prakash srinivasan" <asprakash_83@domain.hid>]

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Deal All,

       I am executing a simple for() loop and like to calculate the time period for this loop. I used rt_timer_read(). As per the document, it mentioned that rt_timer_read() returns the current time expressed in clock ticks. I could not able to get an clear idea about it. Suppose if i convert it by using rt_timer_ticks2ns(), I am not getting the proper output. My code is,



RTIME start, end;

...

...

start=rt_timer_read();

for()

{}

end=rt_timer_read();

printf(TOTAL LOOP TIMING=%ld us\n", (long)((rt_timer_ticks2ns(end-start))/1000);



I would like to convert the ticks into nano seconds first and then into micro seconds. The final result is irrelevant. I am not sure, where is the issue. Help me to find the timings details properly.



In the example program trivial-periodic.c, they mentioned 



"NOTE: printf may have unexpected impact on the timing of your program. It is used here in the critical loop only for demonstration purposes."



Why?

 



-Prakash 



  

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