Time a function

Time a function
You are encouraged to solve this task according to the task description, using any language you may know.

What time does it take to execute a `function' with a given `arguments'.

Use a timer with the least granularity available on your system.

What caveats are there?

This task is intended as a subtask for Measure relative performance of sorting algorithms implementations.

Ada

with Ada.Calendar; use Ada.Calendar;
with Ada.Text_Io; use Ada.Text_Io;

procedure Query_Performance is
   type Proc_Access is access procedure(X : in out Integer);
   function Time_It(Action : Proc_Access; Arg : Integer) return Duration is
      Start_Time : Time := Clock;
      Finis_Time : Time;
      Func_Arg : Integer := Arg;
   begin
      Action(Func_Arg);
      Finis_Time := Clock;
      return Finis_Time - Start_Time;
   end Time_It;
   procedure Identity(X : in out Integer) is
   begin
      X := X;
   end Identity;
   procedure Sum (Num : in out Integer) is
   begin
      for I in 1..1000 loop
         Num := Num + I;
      end loop;
   end Sum;
   Id_Access : Proc_Access := Identity'access;
   Sum_Access : Proc_Access := Sum'access;
   
begin
   Put_Line("Identity(4) takes" & Duration'Image(Time_It(Id_Access, 4)) & " seconds.");
   Put_Line("Sum(4) takes:" & Duration'Image(Time_It(Sum_Access, 4)) & " seconds.");
end Query_Performance;

Example

Identity(4) takes 0.000001117 seconds.
Sum(4) takes: 0.000003632 seconds.

Python

Interpreter: Python

Given function and arguments return a time (in microseconds) it takes to make the call.

Note: There is an overhead in executing a function that does nothing.

import sys, timeit
def usec(function, arguments):
    modname, funcname = __name__, function.__name__
    timer = timeit.Timer(stmt='%(funcname)s(*args)' % vars(),
                         setup='from %(modname)s import %(funcname)s; args=%(arguments)r' % vars())
    try:
        t, N = 0, 1
        while t < 0.2:            
            t = min(timer.repeat(repeat=3, number=N))            
            N *= 10
        microseconds = round(10000000 * t / N, 1) # per loop
        return microseconds 
    except:
        timer.print_exc(file=sys.stderr)
        raise

def nothing(): pass
def identity(x): return x

Example

>>> print usec(nothing, [])
1.7
>>> print usec(identity, [1])
2.2
>>> print usec(pow, (2, 100))
3.3
>>> print map(lambda n: str(usec(qsort, (range(n),))), range(10))
['2.7', '2.8', '31.4', '38.1', '58.0', '76.2', '100.5', '130.0', '149.3', '180.0']

where qsort() implemented on Quicksort page. Timings show that the implementation of qsort() has quadratic dependence on sequence length N for already sorted sequences (instead of O(N*log(N)) in average).