[Mono-bugs] [Bug 342190] [Performance] MS.NET 2.0 is twice faster as mono 1.2. 6 when compressing with SharpZipLib

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https://bugzilla.novell.com/show_bug.cgi?id=342190#c10





--- Comment #10 from Robert Jordan <robertj at gmx.net>  2007-11-20 06:09:19 MST ---
I run some tests on the same machine (Windows XP, Intel Core Duo 2, 2GHz):

randomfile.bin
==============

MS.NET

/ziptest.exe randomfile.bin
ICSharpCode.SharpZipLib, Version=2.84.0.0, Culture=neutral,
PublicKeyToken=1b03e6acf1164f73
SharpZip :00:00:10.7343750
Zlib :00:00:14.4218750


MONO 1.2.6 on Windows:

mono neo:~/src/tests $ mono ./ziptest.exe randomfile.bin
ICSharpCode.SharpZipLib, Version=2.84.0.0, Culture=neutral,
PublicKeyToken=1b03e6acf1164f73
SharpZip :00:00:16.0940000
Zlib :00:00:08.4680000


logfile.txt
===========

MS.NET

ICSharpCode.SharpZipLib, Version=2.84.0.0, Culture=neutral,
PublicKeyToken=1b03e6acf1164f73
SharpZip :00:00:03.9218750
Zlib :00:00:04.1562500


MONO 1.2.6 on Windows

mono neo:~/src/tests $ mono ./ziptest.exe logfile.txt
ICSharpCode.SharpZipLib, Version=2.84.0.0, Culture=neutral,
PublicKeyToken=1b03e6acf1164f73
SharpZip :00:00:07.8440000
Zlib :00:00:02.2650000


zerofile.bin
============

MS.NET

mono neo:~/src/tests $ ./ziptest.exe zerofile.bin
ICSharpCode.SharpZipLib, Version=2.84.0.0, Culture=neutral,
PublicKeyToken=1b03e6acf1164f73
SharpZip :00:00:04.3593750
Zlib :00:00:03.3750000

MONO 1.2.6 on Windows

mono neo:~/src/tests $ mono ./ziptest.exe zerofile.bin
ICSharpCode.SharpZipLib, Version=2.84.0.0, Culture=neutral,
PublicKeyToken=1b03e6acf1164f73
SharpZip :00:00:12.7190000
Zlib :00:00:01.5470000


The first line is the output of 
Console.WriteLine (typeof (GZipOutputStream).Assembly);

=> the tests are using the same SharpZipLib version on both
runtimes.



* randomfile.bin (100MB) is reproducible, since it was generated
  with a known seed using mono on the 2.0 profile:

using System;
using System.IO;

class Test
{
        static void Main ()
        {
                Random rng = new Random (42);
                byte[] bytes = new byte [1024 * 1024];

                Stream stm = File.Create ("randomfile.bin");

                for (int i = 0; i < 100; i++) {
                        rng.NextBytes (bytes);
                        stm.Write (bytes, 0, bytes.Length);
                }

                stm.Close ();
        }
}


* logfile.txt (100MB) was taken from an apache log file.

* zerofile.bin is the output of

  dd if=/dev/zero of=zerofile.bin count=100 bs=1048576


The results show that mono's performance degradation is related
to the compression rate of the data.

See zerofile.bin, where mono performs worst (relatively to MS.NET).


I'm aware that this doesn't help much, but someone who knows
the GZip algorithm should be able to deduce which parts of
the GZip code is performance-critical when zerofile.bin is processed.


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