Re: dacapo benchmarks

["Patrick Olinet" <patrick dot olinet at gmail dot com>]

Hi Andrew,

>  > * The eclipse benchmark from the same suite runs fine with gcj, except
>  > that the results aren't very good. Actually, the results are hardly
>  > better than what you get when you run the eclipse benchmark with gij.
>  > Compare to the others benchmarks results (antlr, hsqldb, luindex,
>  > lusearch) where gcj outperforms gij by a factor of 5 or even more, I'm
>  > a bit suprised. And using "-O2" or "-Os" for gcj invocation doesn't
>  > help.
>
> I'm guessing that eclipse isn't actually spending much time in the
> application program itself, but in the libraries.

You're right. I've first thought that this wasn't the problem since
the whole jar files are compiled into the binary. But after looking
more carefully at the content of one of them, I can see a big
"eclipse.zip" file that contains all the eclipse libraries (class +
jar files). This zip file is put into the binary as it is and its
content is not compiled by gcj but loaded and interpreted at runtime.
That's the reason why. And this would require modifiying the benchmark
code to get rid of this behaviour.

> I prefer never to guess.  I use oprofile to find out for real.

Thanks for the tip. I didn't know about this very convenient tool.


Patrick