WHAT: Solicitation of feedback on the possibility of adding a runtime
services layer to Open MPI to abstract out the runtime.
WHY: To solidify the interface between OMPI and the runtime
and to allow the use of different runtime systems, including different
versions of ORTE.
WHERE: Addition of a new framework to OMPI, and changes to many of the
files in OMPI to funnel all runtime request through this framework.
changes should be required in OPAL and ORTE.
WHEN: Development has started in tmp/rsl, but is still in its
infancy. We hope
to have a working system in the next month.
I am working on creating an interface between OMPI and the runtime
This would make a RSL framework in OMPI which all runtime services
accessed from. Attached is a graphic depicting this.
This change would be invasive to the OMPI layer. Few (if any) changes
will be required of the ORTE and OPAL layers.
At this point I am soliciting feedback as to whether people are
supportive or not of this change both in general and for v1.3.
The current model used in Open MPI assumes that one runtime system is
the best for all environments. However, in many environments it may be
beneficial to have specialized runtime systems. With our current
is not easy to do.
With this in mind, the idea of creating a 'runtime services layer' was
hatched. This would take the form of a framework within OMPI,
all runtime functionality would be accessed. This would allow new or
different runtime systems to be used with Open MPI. Additionally,
with such a
system it would be possible to have multiple versions of open rte
which may facilitate development and testing. Finally, this would
interface between OMPI and the runtime system, as well as provide
documentation and side effects of each interface function.
However, such a change would be fairly invasive to the OMPI layer, and
needs a buy-in from everyone for it to be possible.
Here is a summary of the changes required for the RSL (at least how
1. Add a framework to ompi for the rsl, and a component to support
2. Change ompi so that it uses the new interface. This involves:
a. Moving runtime specific code into the orte rsl component.
b. Changing the process names in ompi to an opaque object.
c. change all references to orte in ompi to be to the rsl.
3. Change the configuration code so that open-rte is only linked
Of course, all this would happen on a tmp branch.
The design of the rsl is not solidified. I have been playing in a
(located at https://svn.open-mpi.org/svn/ompi/tmp/rsl) which
welcome to look at and comment on, but be advised that things here are
subject to change (I don't think it even compiles right now). There
some fairly large open questions on this, including:
1. How to handle mpirun (that is, when a user types 'mpirun', do they
always get ORTE, or do they sometimes get a system specific
likely mpirun will always use ORTE, and alternative launching
be used for other runtimes.
2. Whether there will be any performance implications. My guess is
but am not quite sure of this yet.
Again, I am interested in people's comments on whether they think
such abstraction is good or not, and whether it is reasonable to do
thing for v1.3.
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