My first guess would be that the jit is better at static calls than virtual.
Nick
Patrick LAM wrote:
> We have some machines running Debian 2.1 here (libc 5.4.46), and we are
> running the pre-v2 Linux port of Java.
>
> There are strange timings for the following programs. In particular, the
> static version runs at about half the speed of the nonstatic version,
> which seems backwards; static takes 232s and nonstatic takes 123s.
> Normally, the static call should be faster to execute, since there is less
> work to do. Does anyone have any ideas about why this is the case?
>
> pat
>
> // virtual invokes.
>
> class myprog {
>
> public static void main(String[] args) {
> int i,j,n;
>
> System.out.println("Beginning");
> long begTime = System.currentTimeMillis();
> System.out.println(begTime);
>
> Bidule bid = new Bidule();
>
>
> for (n=1; n<50000000; n++) {
> bid.change(1);
> bid.change(2);
> bid.change(3);
> bid.change(4);
> bid.change(5);
> bid.change(6);
> }
>
> System.out.println("End");
> long endTime = System.currentTimeMillis();
> System.out.println(endTime);
> System.out.println(" lasting : " + (endTime-begTime) );
> }
> }
>
> class Bidule{
> int i;
> public Bidule() {
> i=0;
> }
>
> public void change(int new_i) {
> //System.out.println("former i : "+i+" new i : "+new_i);
> i=new_i;
> }
> }
>
> // myprog_static
> class myprog_static {
>
> public static void main(String[] args) {
> int i,j,n;
>
> System.out.println("Beginning");
> long begTime = System.currentTimeMillis();
> System.out.println(begTime);
>
> Bidule_static bid = new Bidule_static();
>
>
> for (n=1; n<50000000; n++) {
>
> Bidule_static.change(bid, 1);
> Bidule_static.change(bid, 2);
> Bidule_static.change(bid, 3);
> Bidule_static.change(bid, 4);
> Bidule_static.change(bid, 5);
> Bidule_static.change(bid, 6);
>
> }
>
> System.out.println("End");
> long endTime = System.currentTimeMillis();
> System.out.println(endTime + " lasting "+ (endTime-begTime));
> }
> }
>
> class Bidule_static{
> int i;
> public Bidule_static() {
> i=0;
> }
>
> public static void change( Bidule_static bidule, int new_i) {
> bidule.i=new_i;
> }
> }
>
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