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Re: Speed Impact experiment on GCJ


Andrew Haley wrote:
I tried gcj against IBM's JIT -- still the fastest JIT AFAIAA.
(Disclaimer: this is an old 32-bit version of IBM's JIT, and a newer
one may be better.)


I made some similar tests using the HotSpot 1.5.0_06 server JVM on a Fedora Core release 4. As you can see, my gcj is slightly older then yours. Don't know how much that matters. Results below:


Regards,
Thomas Hallgren


[thhal@localhost gcjtest]$ gcj --version gcj (GCC) 4.0.0 20050519 (Red Hat 4.0.0-8) Copyright (C) 2005 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[thhal@localhost gcjtest]$ java -version -server
java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
Java HotSpot(TM) Server VM (build 1.5.0_06-b05, mixed mode)

HotSpot server without JIT:

[thhal@localhost gcjtest]$ time java -server -Djava.compiler=none Client task.test servers.d result.d

real    0m55.379s
user    0m53.726s
sys     0m1.379s

200.0   7897
300.0   11791
400.0   15660
500.0   19588

HotSpot server JIT:

[thhal@localhost gcjtest]$ time java -server Client task.test servers.d result.d

real    0m0.510s
user    0m0.073s
sys     0m0.393s

200.0   39
300.0   1
400.0   0
500.0   1

REMARK: Obviously, the JIT discovers that the loop is not really a loop sometime
during the first iterations and decides to optimize pretty hard...

gcj at -O0:

[thhal@localhost gcjtest]$ time ./client task.test servers.d result.d

real    0m9.609s
user    0m9.240s
sys     0m0.288s

200.0   1327
300.0   2053
400.0   2662
500.0   3339

gcj at -O3:

[thhal@localhost gcjtest]$ time ./client task.test servers.d result.d

real    0m1.469s
user    0m1.265s
sys     0m0.202s

200.0   184
300.0   276
400.0   346
500.0   442


I get:

[aph@zorro ~]$ java -version
java version "1.4.2"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2)
Classic VM (build 1.4.2, J2RE 1.4.2 IBM build cxia32142-20041210 (JIT enabled: jitc))

[aph@zorro ~]$ gcj --version
gcj (GCC) 4.1.0 20060128 (Red Hat 4.1.0-0.17)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

IBM without a JIT:

[aph@zorro ~]$ time java -Djava.compiler=none Client task.test servers.d result.d
Warning: JIT compiler "none" not found. Will use interpreter.

real    1m6.508s
user    1m6.340s
sys     0m0.016s

200.0   9315
300.0   13993
400.0   18636
500.0   23271

IBM with a JIT:

[aph@zorro ~]$ time java Client task.test servers.d result.d

real    0m2.521s
user    0m2.480s
sys     0m0.024s

200.0   334
300.0   501
400.0   671
500.0   835

gcj at -O0:

[aph@zorro ~]$ time ./client task.test servers.d result.d
time ./client task.test servers.d result.d

real    0m6.982s
user    0m6.932s
sys     0m0.024s

200.0   997
300.0   1475
400.0   1988
500.0   2491

gcj at -O3:

[aph@zorro ~]$ time ./client task.test servers.d result.d

real    0m1.236s
user    0m1.220s
sys     0m0.016s

200.0   167
300.0   252
400.0   336
500.0   425

32-bit mode doesn't seem to make any difference to us. gcj at -O3 -m32:

[aph@zorro ~]$ time ./client task.test servers.d result.d

real    0m1.236s
user    0m1.228s
sys     0m0.008s

200.0   167
300.0   251
400.0   335
500.0   418

And, just for laughs, gij:

[aph@zorro ~]$ time gij Client task.test servers.d result.d

real    0m41.280s
user    0m41.047s
sys     0m0.024s

200.0   5804
300.0   8685
400.0   11587
500.0   14468

Andrew.



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