[GNU Crypto] performance issues

[Raif S. Naffah]

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hello there,

just before i call it a day ;-) i'd like to share with you the results 
of a test i wrote today:

the code is:

- ----- begin Performance.java -----
public class Performance {
   private static final int ROUNDS = 100000;
   // default constructor
        
   public static final void main(String[] args) {
      int i, j;
      long t1 = 0, t2 = 0;
      // comparing System.arraycopy to plain for loop
      byte[] src = new byte[256];
      byte[] dst = new byte[256];
      for (i = 0; i < 256; i++) {
         src[i] = (byte) i;
      }
      t1 = -System.currentTimeMillis();
      for (i = 0; i < ROUNDS; i++) {
         for (j = 0; j < 256; j++) {
            dst[j] = src[j];
         }
      }
      t1 += System.currentTimeMillis();
      t2 = -System.currentTimeMillis();
      for (i = 0; i < ROUNDS; i++) {
         System.arraycopy(src, 0, dst, 0, 256);
      }
      t2 += System.currentTimeMillis();

      System.out.println("*** Test #1: System.arraycopy / for loop");
      System.out.println("    for loop: "+t1);
      System.out.println("   arraycopy: "+t2);
   }
}
- ----- end Performance.java -----

this is how i compiled and tested it:

$ jikes -classpath /usr/java/jdk1.3.1_05/jre/lib/rt.jar:. -d classes 
src/Performance.java
$ java -classpath classes Performance
*** Test #1: System.arraycopy / for loop
    for loop: 350
   arraycopy: 26
$ gcj --main=Performance -o Performance src/Performance.java
$ ./Performance
*** Test #1: System.arraycopy / for loop
    for loop: 397
   arraycopy: 18
$ gcj -march=athlon-xp -O3 -fno-bounds-check --main=Performance -o 
Performance src/Performance.java
$ ./Performance
*** Test #1: System.arraycopy / for loop
    for loop: 72
   arraycopy: 19


* Jikes Compiler - Version 1.17 - 27 September 2002
* java version "1.3.1_05"
* gcj (GCC) 3.2 20020903 (Red Hat Linux 8.0 3.2-7)


i intend to add more tests to this class so as to gain better insight at

a. which constructs have better performance impact, and
b. which alternative to use to get the most out of GCJ.


ideas and suggestions are welcome + cheers;
rsn
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