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Re: [Vala] Why Vala is slower than Mono?

Am Samstag, den 02.06.2012, 15:47 +0200 schrieb pinggi centrum cz:

I read that Vala is fast because it is translated to C and then compiled to the machine code. I have been 
encouraged to find out how much Vala is faster than Mono. So I made a speed test.
 
 The test program creates an array 100 000 000 integers long and then it fills the array with numbers 
incrementing by one. Both time durations are printed.
 
 Firstly, C# source:
 
 using System;
 using System.Diagnostics;
 
 namespace MonoTest
 {
     class MainClass
     {
         public static void Main (string[] args)
         {
             Stopwatch t1 = new Stopwatch ();
             Stopwatch t2 = new Stopwatch ();
             
             t1.Start ();
         
             int[] matrix = new int[100000000];
             int i;
 
             t1.Stop ();
 
             t2.Start ();
     
             for (i = 0; i < matrix.Length; i++) {
                 matrix [i] = i;
             }
 
             t2.Stop ();
     
             Console.WriteLine ("Took: creating: {0}, processing: {1}", t1.ElapsedMilliseconds / 1000.0, 
t2.ElapsedMilliseconds / 1000.0);
         }
     }
 }
 
 Compiled by: dmcs Main.cs
 Run by: ./Main.exe
 Output: Took: creating: 0.388, processing: 0.212
 
 Now, Vala source:
 
 using GLib;
 
 public class HelloVala: GLib.Object {
     
     public static int main (string[] args) {
 
         Timer t1 = new Timer();
         Timer t2 = new Timer();
             
         t1.start();
         
         int[] matrix = new int[100000000];
         int i;
 
         t1.stop();
 
         t2.start();
     
         for (i = 0; i < matrix.length; i++)
         {
             matrix[i] = i;
         }
 
         t2.stop();
     
         stdout.printf("Took: creating: %f, processing: %f", t1.elapsed(), t2.elapsed());
         
         return 0;
     }
 }
 
 Compiled by: valac main.vala
 Run by: ./main
 Output: Took: creating: 0.000034, processing: 2.101480
 
 Compiled by: valac main.vala -X -O0
 Run by: ./main
 Output: Took: creating: 0.000032, processing: 2.058595
 
 Compiled by: valac main.vala -X -O1
 Run by: ./main
 Output: Took: creating: 0.000015, processing: 0.434786
 
 Compiled by: valac main.vala -X -O2
 Run by: ./main
 Output: Took: creating: 0.000034, processing: 0.455629
 
 Compiled by: valac main.vala -X -O3
 Run by: ./main
 Output: Took: creating: 0.000033, processing: 0.364947
  
 Compiled by: valac main.vala -X -Ofast
 Run by: ./main
 Output: Took: creating: 0.000019, processing: 0.352727
 
 Compiled by: valac main.vala -X -Os
 Run by: ./main
 Output: Took: creating: 0.000033, processing: 0.415005
 

 It seems that Vala is 10 times slower than mono by default and 2 times with optimizations.
 How is that possible?
 

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Note that in Vala you can define functions outside of classes. I guess
Mono will optimize away the class definition, since it is not referenced
anywhere. But in Vala you have the added cost of the glib type system.
In your example you can get rid of the class and rewrite to:

public void main (string[] args) {
    Timer t1 = new Timer();
    Timer t2 = new Timer();

    t1.start();

    int[] matrix = new int[100000000];
    int i;

    t1.stop();

    t2.start();

    for (i = 0; i < matrix.length; i++) {
        matrix[i] = i;
    }

    t2.stop();
    stdout.printf("Took: creating: %f, processing: %f\n", t1.elapsed(),
t2.elapsed());
}

Now with optimization turned on I get roughly the same times. That said,
I am not a Vala developer, so maybe someone else has a better
explanation.
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