Subroutine Call Is Expensive

The prologue and epilogue associated with each procedure are overhead that is necessary but does not do user computation.

• Even in scientific Fortran, procedure call overhead may account for 20% of execution time.

• Fancier languages have higher procedure call overhead.

• Relative overhead is higher for small procedures.

• Breaking a program into many small procedures increases execution time.

• A GOTO is much faster than a procedure call.

• Modern hardware architecture can help:
  • Parameter transfer

  • Stack addressing

  • Register file pointer moved with subroutine call