Hi, guys:

Thank you so much for your time and suggestions, I finally used PooLpi's solution which looks easy to implement, and I will remember the potential side-effects of "use Benchmark" under IO

BTW. I also came up with another way: what about putting the running script into the background and then print the result into an external tmp file or whatever, i.e.(with my original script, under bash, Linux for sure)

 stty tostop
 perl mytest.pl > result.txt &
 tail -n4 result.txt
[download]

Any side effects with this approach?? Thanks

Best,

Lihao(XC)