On 11/6/07, Tim Ellison <[EMAIL PROTECTED]> wrote:
> > It seems to me that it could be improved further if some magic
> > implementing sqrt() will be used instead on native call.
>
> Looks like we have to go this path, since the hacked intrinsics are
> still 4x slower if I'm reading this properly.
You're reading right. We are still 4x slower than Sun 1.6.0_02
> > Moreover, AFAIU the (3) approach is safe since IEEE754 compatibility
> > must be preserved only for strict mode, whereas (3) approach
> > implements fastpath for non-strict mode.
>
> Yes, I modified my microbench to use both strict and non-strict in the
> same run and there is a noticeable difference on Sun 6.0:
> Math Result = 6.666661664588418E8 in 30ms
> StrictMath Result = 6.666661664588418E8 in 1012ms
That's weird :S Here's what I've got on this modified microtest:
========================================================
public class testSqrt {
final static int count = 10000000;
public static void main(String[] args) {
// warm-up
double result = 0.0d;
for (long i = 0; i < 1024*1024*10; i++) {
result += Math.sqrt((double) i);
result += StrictMath.sqrt((double) i);
}
System.out.println("Warmup finished: " + result);
long start;
// Timed run
result = 0.0d;
start = System.currentTimeMillis();
for (int i = 0; i < count; i++) {
result += Math.sqrt((double) i);
}
System.out.println("Math Result = " + result + " in "
+ (System.currentTimeMillis() - start) + "ms");
// Timed run
result = 0.0d;
start = System.currentTimeMillis();
for (int i = 0; i < count; i++) {
result += StrictMath.sqrt((double) i);
}
System.out.println("StrictMath Result = " + result + " in "
+ (System.currentTimeMillis() - start) + "ms");
}
}
========================================================
java version "1.5.0_10"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_10-b03)
Java HotSpot(TM) Client VM (build 1.5.0_10-b03, mixed mode, sharing)
Warmup finished: 4.527292719905836E10
Math Result = 2.1081849486439312E10 in 140ms
StrictMath Result = 2.1081849486439312E10 in 9235ms
----------------
java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) Client VM (build 1.6.0-b105, mixed mode, sharing)
Warmup finished: 4.527292719905836E10
Math Result = 2.1081849486439312E10 in 141ms
StrictMath Result = 2.1081849486439312E10 in 141ms
---------------
java version "1.6.0_02"
Java(TM) SE Runtime Environment (build 1.6.0_02-b06)
Java HotSpot(TM) Client VM (build 1.6.0_02-b06, mixed mode)
Warmup finished: 4.527292719905836E10
Math Result = 2.1081849486439312E10 in 156ms
StrictMath Result = 2.1081849486439312E10 in 140ms
---------------
Harmony (clean)
Apache Harmony Launcher : (c) Copyright 1991, 2006 The Apache Software
Foundation or its licensors, as applicable.
java version "1.5.0"
pre-alpha : not complete or compatible
svn = r589548, (Nov 6 2007), Windows/ia32/msvc 1310, release build
http://harmony.apache.org
Warmup finished: 4.527292719905836E10
Math Result = 2.1081849486439312E10 in 12078ms
StrictMath Result = 2.1081849486439312E10 in 12016ms
----------------
Harmony (patched)
Apache Harmony Launcher : (c) Copyright 1991, 2006 The Apache Software
Foundation or its licensors, as applicable.
java version "1.5.0"
pre-alpha : not complete or compatible
svn = r589548, (Nov 6 2007), Windows/ia32/msvc 1310, release build
http://harmony.apache.org
Warmup finished: 4.5272927199206406E10
Math Result = 2.1081849486508232E10 in 3406ms
StrictMath Result = 2.1081849486439312E10 in 12058ms
----------------
You see, Sun 1.6.0 behaves fast even in strict mode.
Thanks,
Aleksey.
