Speaker
Describe the added value of the Grid for the scientific/technical activity you (plan to) do on the Grid. This should include the scale of the activity and of the potential user community and the relevance for other scientific or business applications
The first phase of the Grid has focussed on very loosely-coupled
applications such as
those common in high-energy physics. However, there is a
significant community of
computational scientists who need to run more tightly-coupled
applications using
standards such as MPI. Most of these scientists currently run
their jobs directly on
clusters. If they were to migrate to the Grid, they would be able
to access multiple
clusters with a single sign-on. This would be of particular
benefit to existing
multi-site collaborations. To date, the lack of good MPI support
has been one of the
factors preventing greater adoption of the Grid by such
scientists. Improvements
would open up a range of application areas.
Describe the scientific/technical community and the scientific/technical activity using (planning to use) the EGEE infrastructure. A high-level description is needed (neither a detailed specialist report nor a list of references).
This work has been undertaken to improve support for parallel
applications using MPI.
Such applications are common in many fields of computational
science including earth
sciences, computational chemistry, astrophysics and climate
modelling. Existing users
of high-performance clusters are accustomed to MPI support and in
many cases it is a
pre-requisite for migrating their applications to the Grid.
Better MPI support would
greatly increase the potential user-base of the EGEE Grid.
With a forward look to future evolution, discuss the issues you have encountered (or that you expect) in using the EGEE infrastructure. Wherever possible, point out the experience limitations (both in terms of existing services or missing functionality)
The solutions we propose are workable and can be rapidly
implemented by sites. Even
without changes to the core middleware, we will be able to
provide users with a
sensible methodology for submitting MPI jobs and site admins with
a practical recipe
for configuring their sites. There are issues that will need to
be addressed in the
future including methods for selecting custom interconnects and
compilers and
flexible support for parallel jobs in the WMS.
Report on the experience (or the proposed activity). It would be very important to mention key services which are essential for the success of your activity on the EGEE infrastructure.
It has been technically possible to run MPI jobs on the Grid for
some time. However,
support has been lacking in these areas: i) standards for
advertising availability of
MPI libraries; ii) recipes for configuring sites for MPI; iii)
clear user
instructions for locating MPI sites and submitting jobs; iv)
middleware limitations
that assume (and force) inflexible methods for submitting MPI
jobs that are not
acceptable to many sites.
Based on discussion within EGEE and with the int.eu.grid (I2G)
project, we have
formulated simple solutions that should greatly ease the use of
MPI code on the Grid.
The approach is for users to submit their jobs wrapped in a
script that performs any
necessary setup (e.g. compilation), using site-defined
environment variables and
I2G's MPI-start package to execute their binary using the desired
version of MPI.
Script templates will be made available for users to customise.
We have also produced
guidelines for configuring sites to support MPI.
