Well bug 44132 [1] has been a real thorn in my side for some time.  The
problem being that all mpi implementations currently in portage block each
other.  This is a real pain for any serious administrators, makes testing
new/other implementations too time-consuming, and in my opinion has probably
slowed any progress related to getting cluster applications into portage or
the overlays.

All that being said, I set out to do something about it.  Donnie Berkholz was
nice enough to help me out early on and ended up suggesting that I look
at crossdev.  I shamelessly ripped off the aforementioned script and tuned
it for mpi implementations and packages.  It should be noted that all the
changes I've implemented do [should, hopefully will] not effect the way the
packages behave now, rather it just adds another option.  The idea is as
follows.

sys-cluster/empi:  Does the same stuff that crossdev does.  You create a new
implementation root by specifying a name and mpi implementation package to
build it with. [2]  Empi adds these to an overlay under a new category with
the name you gave.  The ebuilds inherit mpi.eclass which handles pushing all
the files to /usr/lib/mpi/<name>, and providing files for eselect-mpi.

Later, you can add packages by specifying the category name and packages to
install.  Empi grabs the ones that inherit mpi (including deps), adds them to
the overlay and emerges.  The deps stuff hasn't been tested all that much.

app-admin/eselect-mpi:  Used to setup a user's environment to call a named
implementation install.  Basically does this by dropping a bash-sourceable
file in ${HOME}/.env.d/mpi.  The not-so-fun part is that the user then has to
remember to source that file.  Also used a fair amount by mpi.eclass.

I threw some quick notes showing commands and output up in my devspace. [3]
If anyone is at all interested, please try this out and let me know what you
think.  Even if you don't try it out but have ideas/comments/rants, I'm all ears.

Current overlay has the following ready to be tried out.
eselect-mpi/eselect-mpi-0.0.1
sys-cluster/empi-0.1
sys-cluster/hpl-1.0-r3
sys-cluster/lam-mpi-7.1.4-r1
sys-cluster/mpi-examples-1.0
sys-cluster/openmpi-1.2.5-r1

A couple of final words, hpl and mpi-examples currently wouldn't work without
empi, mainly because I'm lazy :)  Also I still haven't figured out a good way
to handle do{man,doc,www} etcetera, ideas are welcome.  There's still a fair
amount of work to be done, but I wanted to see if anyone had any feedback
regarding the general concept first before pushing on.

You can pull the overlay from rsync://cold-front.ath.cx/mpi (for now...)

Thanks,


[1] http://bugs.gentoo.org/show_bug.cgi?id=44132
[2] Currently openmpi-1.2.5-r1 or lam-mpi-7.1.4-r1
[3] http://dev.gentoo.org/~jsbronder/README.empi.txt

-- 
Justin Bronder