Re: [PATCH] Speedup gij/libjava loading on darwin

[Geoff Keating <geoffk at geoffk dot org>]

On 19/08/2005, at 11:48 PM, Andreas Tobler wrote:

> Geoffrey Keating wrote:
>
> > Andrew Pinski <pinskia@physics.uc.edu> writes:
> >
> > >     * Makefile.am (extra_ldflags_libjava): New variable to
> > >     substitute in.
> > >     (LIBLINK): Add extra_ldflags_libjava to it.
> > >     * configure.ac (extra_ldflags_libgfortran): Set for *-darwin* to
> > >     "-Wl,-single_module".
> > This is OK.
>
> I'm not very happy with this patch. I already mentioned it to Andrew.
> Here on tiger 10.4.2 the situation gets worse. See the figures below.
> Would you agree to do this change only for darwin7*?
>
> Index: configure.ac
> ===================================================================
> RCS file: /cvs/gcc/gcc/libjava/configure.ac,v
> retrieving revision 1.36
> diff -u -r1.36 configure.ac
> --- configure.ac        19 Aug 2005 05:14:11 -0000      1.36
> +++ configure.ac        20 Aug 2005 06:45:40 -0000
> @@ -670,7 +670,7 @@
>
>  # extra LD Flags which are required for targets
>  case "${host}" in
> -  *-darwin*)
> +  *-darwin7*)
>      # on Darwin -single_module speeds up loading of the dynamic  
> libraries.
>      extra_ldflags_libjava=-Wl,-single_module
>      ;;
>
> Afaik, the dyld and co got rewritten in tiger and now we have a  
> slow down. Maybe ld needs a rewrite too?
>
>
> Here the figures :)

That's not supposed to happen!  Yes, this was unexpected, let's go  
back to multi-module on darwin8+ at least until we can work out what  
the problem is.

I put your figures into a little table so I could see the pattern.   
It looks like this:

               single  multi  slowdown
compile.exp    1017     601   69%
lang.exp       4362    2811   56%
mauve.exp      8982    5903   52%

since compile.exp slowed down by a lot and the execute tests not so  
much, it looks pretty likely that the problem is in ld.  I expect  
that dyld is faster, but ld is so much slower that it's completely  
hiding the benefit.

So, the first thing I'll do is reproduce the problem and then file a  
bug report.

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