Re: [Jython-users] slow JPython math on HP??

[<bc...@wo...>]

On Fri, 12 Jan 2001 22:20:52 -0800 (PST), you wrote:

>Why is math sooooooooo slow on HP versus Linux??  For the example below
>I calculate the time to calculate 2L**10000 on HP and Linux.  It's over
>2,000 faster on a Linux PC (512 MHz dual Celeron) than on a HP (K box,
>4 processor, 180 MHz).  
>
>This particular example is not critical to my application.  I just
>focus on it because of the dramatic difference in performance on HP
>versus other platforms.  Might this be a clue as to a problem with HP??
>
>
>HP:
>
>JPython 1.1+09 on java1.2.2.05 (JIT: null)
>86.5       <--  interpretted, very slow
>
>JPython 1.1+09 on java1.2.2.05 (JIT: HP)
>11.8     <-- classic JIT
>
>JPython 1.1+09 on java1.2.2.05 (JIT: null)
>14.9     <--  HotSpot JIT

My numbers are on Win2k & JDK1.3 & 300Mhz P3:

Jython 2.0beta2 on java1.3.0 (JIT: null)
37.74500000476837  <-- interpretted

Jython 2.0beta2 on java1.3.0 (JIT: null)
4.736999988555908  <-- hotspot 

While somewhat faster then your HP it is in the within the same range.

>Linux        512 MHz   dual Celeron (brain dead?) Pentium
>
> Linux: /home/mudd[1]  jpython
>JPython 1.1 on java1.2.2-RC2 (JIT: javacomp)
>Copyright (C) 1997-1999 Corporation for National Research Initiatives
>>>> from time import time
>>>> t1=time(); x=2L**10000; delay=time()-t1; print delay
>0.00499        <-- About 2,400 times faster than HP's best numbers??!?
>>>>

That's fast! Does it actually calculate the correct value?

The power calculation is done fully by the java.math.BigInteger
implementation. The BigInteger.pow() on JDK1.3 (and HP too I expect) is
implemented in java as some kind of loop which I don't understand.

If the linux JVM are doing its BigInteger stuff in native code, that
might explain the difference.

regards,
finn