Re: AIX linking: -berok in aclocal.m4 and libtool

[Daniel Pocock]

Ralf Wildenhues wrote:
> Hello Daniel,
>
> * Daniel Pocock wrote on Sat, Jan 16, 2010 at 02:09:55PM CET:
>   
> > Could anyone share any advice on using autoconf and automake to
> > prepare a distribution tarball that will work on AIX?  Normally, I
> > build the tarball on Linux (Debian 5).  The AIX users need to be
> > able to use the tarball to build an executable (gmond), a static
> > library (libmetrics) and a bunch of DSOs (e.g. modcpu.so)?
> >
> > Some AIX users of Ganglia have raised queries about the -berok
> > linker flag in aclocal.m4, and whether it is necessary to patch
> > aclocal.m4 to remove this flag.
> >
> > We're also trying various other things to improve the AIX support,
> > e.g. adding "-Wl,-bexpfull" to LDFLAGS or GLDFLAGS in various
> > places.
> >
> > This all comes out of
> > - bug report (Ganglia bug 227)
> > http://bugzilla.ganglia.info/cgi-bin/bugzilla/show_bug.cgi?id=227
> > - and subsequent email discussion 
> > http://www.mail-archive.com/address@hidden/msg05463.html
> >     
>
> I haven't looked into this in detail yet; I would like to, but it might
> be a while.  Is the source code of this package available for download
> (URL)?  What other software would I need to build this?  Thanks.
>   
I've created a branch for testing on AIX:

 
http://ganglia.svn.sourceforge.net/viewvc/ganglia/branches/monitor-core-3.1-aix/

Snapshots of the AIX branch and release branch are here:

 http://www.pocock.com.au/ganglia/test/


> A few general comments:
>
> This is probably a Libtool issue rather than an Automake one.
>
> I noticed in the PR a diff against libtool.  I hope you're not putting
> the generated libtool script in version-control anywhere.
>   
It is not in SVN, it is put there when we bootstrap - Michael has been 
applying the diff after downloading the tarball.  I want to improve the 
tarball so he won't need to do this.
> Issues with modules on AIX are often fixed most easily by using
> runtimelinking.  You enable that with libtool by adding -Wl,-brtl
> to LDFLAGS at configure time:
>   ./configure LDFLAGS=-Wl,-brtl
>
> This has a small performance impact, which is why it is not the default.
>   
Thanks for this suggestion - we will try that and add it to the docs for 
AIX users.

Ganglia is essentially a performance monitoring agent, so we are keen to 
minimize any impact it has on the machine.

Does this -brtl option just impact the performance at the time when the 
shared object is loaded, or does it impact ever function call?