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

Jonathan Shore jonathan.shore at gmail.com
Thu Jan 28 21:00:07 EST 2010


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 ...



using System;

namespace Performance

	public class ArrayTest
		public static double test1 (double[] vec)
			double sum = 0;
			for (int i = 8 ; i < vec.Length ; i++)
				vec[i] = 2*vec[i] - vec[i-1];
				for (int j = 1 ; j < 8 ; j++)
					sum += 1.3 * vec[j-1];
			return sum;

		public static void Main (string[] argv)
			int iterations = argv.Length > 0 ? int.Parse(argv[0]) : 1000;
			double[] vec = new double[100000];
			for (int i = 0 ; i < vec.Length ; i++)
				vec[i] = i;
			DateTime Tstart = DateTime.Now;
			Console.WriteLine ("starting performance test on " + iterations + " iterations");
			double sum = 0;
			for (int i = 0 ; i < iterations ; i++)
				sum += test1 (vec);
			DateTime Tend = DateTime.Now;
			TimeSpan Tspan = Tend - Tstart;
			Console.WriteLine ("ending performance test on " + iterations + " iterations, time: " + Tspan.Seconds + ":" + Tspan.Milliseconds);

			Console.WriteLine ("result: " + sum);

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