How do I profile in DrScheme?

Question

How Do I profile my functions using DrScheme?

(require profile) 
(define (factorial n)
  (cond
    ((= n 1) 1)
    (else (* n (factorial (- n 1))))))

(profile factorial)

The above code returns

Profiling results
-----------------
  Total cpu time observed: 0ms (out of 0ms)
  Number of samples taken: 0 (once every 0ms)

====================================
                        Caller
Idx  Total    Self    Name+srcLocal%
     ms(pct)  ms(pct)   Callee
====================================
>

I tried: - (profile (factorial 100))
- (profile factorial) (factorial 100)
But it gives me the same result. What am I doing wrong?

Answer 1

I'm not familiar with the profile module in PLT Scheme, but perhaps you have to actually call the function?

(profile (factorial 1000))

Answer 2

Have you tried cranking up N in (profile (factorial N)) until there's a noticeable pause?

(factorial 100) is the kind of thing a modern computer should be able to do in <1ms.

Just skimming the documentation makes me suspect its just a matter of factorial being too fast to easily profile for that case.