Re: Performances with gcj

[Benjamin de Dardel <benjamin dot dedardel at gmail dot com>]

Hi Francesco,

Thanks for your response. I had already tryed to optimize the code with 
the java file, but it didn't work :
$ gcj -0 --main=PipeTest -o test.bin PipeTest.java
gcj: unrecognized option '-0'

With class files, compilation works... but performances decrease !
May be it's beacause of the threads. I don't know. I'll do some other 
tests in the next days.

# test5
$ gcj -C PipeTest.java
$ gcj -O2 --main=PipeTest -o test.bin PipeTest.class Consumer.class 
Producer.class Filter.class

real    21m59.844s
user    5m26.070s
sys     9m52.130s

# test6
$ gcj -C PipeTest.java
$ gcj -O3 --main=PipeTest -o test.bin PipeTest.class Consumer.class 
Producer.class Filter.class

real    25m34.394s
user    6m12.250s
sys     11m4.440s

ffileppo a écrit :
> > Hi all,
> >
> > I had to release a program that executes an external process and gets 
> > its standard output.
> > I implemented a solution with threads and pipes to redirect inputs and 
> > outputs (cf PipeTest.java).
> >
> > I choose the 'find /' command to test it.
> > I'm very surprised about gcj performances which are 5x slowly than sun jvm.
> > In fact, I expected that my compiled program would be faster than all jvm.
> >
> > Do you have an idea about these differences ?
> > Is that the gnu classpath implementation which is quiet slow ?
> >
> > Regards,
> > Benjamin
> >
> > # test1 : bash
> > $ time find /
> > real    2m6.054s
> > user    0m5.260s
> > sys     0m6.990s
> >
> > # test2 : compilation with gcj
> > $ gcj --main=PipeTest -o test.bin PipeTest.java
> > $ time test.bin
> > real    18m50.632s
> > user    4m56.380s
> > sys     8m31.940s
> >
> > real    19m38.148s
> > user    5m9.660s
> > sys     9m44.710s
> >
> > # test3: interpretation with gij
> > $ gcj -C PipeTest.java
> > $ time gij PipeTest
> >
> > real    22m39.882s
> > user    6m7.580s
> > sys     10m26.350s
> >
> > # test4 : interpretation with java
> > $ javac PipeTest.java
> > $ time java PipeTest
> > real    3m35.035s
> > user    1m18.710s
> > sys     0m11.730s
> >
> > ##### compilers #####
> > $ gcj --version
> > gcj (GCC) 4.2.3 (Ubuntu 4.2.3-2ubuntu6)
> >
> > $ javac -version
> > javac 1.6.0_03
> >
> >     
>
> You need to pass -O2 or -O3 option to gcj compiler (no optimization is enabled by default).
> Please take a look at other posts about gcj performance (http://gcc.gnu.org/ml/java/2008-05/msg00017.html).
>
> Francesco
>
>
>
>
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