Re: [Mono-list] mono performance, 20x differential with Java (what am i doing wrong)

[Rolf Bjarne Kvinge]

Hi,

Can you post the source code for the java sample? I have a hard time
understanding how the sample can run so fast with java, here I get the
following results:

C#: 3.346 seconds
C (compiled with gcc –O3, see attached source code): 1.132 seconds

Rolf


>Hi,
>
>I'm quite familiar with both the .NET and Java development environments,
but only recently have begun to experiment with mono, so forgive me if I'm
not clued-in.   
>
>I specialize in numerical work that often involves a lot large-scale array
manipulation for linear algebra, timeseries, etc.    My main production
platforms are OSX and Linux.   I've been doing most of my work on the JVM
over the >past few years, though spent a couple of years with .NET when it
was pre-release / pre-1.0.  
>
>My main interest is in Ocaml, particularly the F# variant as the basis for
my numerical work.
>
>One of the first things I do when considering a platform is run benchmarks,
as performance is critical for what I do.    Starting with C# I wrote a test
to gauge the array-access overhead associated with the platform.  Without
>knowing how to tweak the mono runtime to turn on any particular
optimisations, the results were quite poor for this specific test (see code
at the end of this posting).
>
>
>The test on my MacPro 2.6 Ghz / Snow Leopard with mono 2.6.1 gave the
result of:
>
>       16 sec, 130 ms for 1000 iterations
>
>the same code, modified just for IO, etc on the Java VM (without -server)
 gave a runtime of:
>
>        0 sec, 831 ms
>
>changing the # of iterations to higher amounts did nothing to improve the
ratio.   Java is 20x faster in this benchmark.
>
>I could not find any documentation concerning settings for the -optimize
flag on the mono VM, so perhaps there is a setting I should be using.   
>
>Secondly, I saw the posting concerning the optional use of LLVM.  I have
not been able to build mono on OSX as am having problems building glib.  I'm
wondering whether anyone has a packaged up version of glib or better a
packaged up >version of mono with LLVM enabled.
>
>I have heard only good things about LLVM performance, so hoping that this
will help address this gap.   Hopefully I am doing something wrong here and
the performance is much closer.   Test code below ...
>
>regards
>
>Jonathan
--
http://tr8dr.wordpress.com/


#include <stdio.h>
#include <string.h>

double test1 (double *vec, int length)
{
        double sum = 0;
        int i, j;
        for (i = 8; i < length; i++) {
                vec [i] = 2 * vec [i] - vec [i-1];
                for (j = 1; j < 8; j++)
                        sum += 1.3 * vec [j - 1];
        }
        return sum;
}

int main (int argc, char **argv)
{
        const int iterations = 1000;
        const int length = 100000;
        double *vec = malloc (length * sizeof (double));
        int i;

        for (i = 0; i < length; i++) {
                vec [i] = i;
        }
        
        double sum = 0;
        for (i = 0; i < iterations; i++)
                sum += test1 (vec, length);

        printf ("result: %f\n", sum);   
}
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