Measuring the Runtime of Applications in Linux

Measuring the Runtime of Applications in Linux

I have a bunch of applications which are compiled via their own Makefiles.
Could you please let me know what can be the best way to measure their
runtime? I have tried "time" command in linux but it does not have that
much accuracy and stability in the result. I also tried to add
clock_gettime() function, however, there were two issues associated with
it. 1) The number of applications are too much to do this. 2) Even if I
can add clock_gettime() to all of the applications, I do not know how to
add "-lrt" to their Makefiles.
Thanks