Tuesday, May 19, 2009

Hybrid Afternoon

Tuesday afternoon was essentially dedicated to topics around heterogeneous hardware. The special focus was laid on the Cell/B.E. Architecture.
Wei Huang from NCAR introduced a new tool which helps to get organized with FORTRAN codes. It greatly support a developer in understanding other people's codes and as well as identify design flaws in his own one.
It allows to easily visualize the call tree and module use. In addition it adds things like variable and function use counts.

Holger Brunst from the Technical University of Dresden showed how performance analysis data gathered on Cell code can be visualized and what information are available from it.

Implementing the same mathematical method for both, Cell and GPU platforms gives despite of the amount of work a deep insight on the performance differences especially under consideration that data has to be moved to and from the processing elements. Jose gave an analysis and comparison of how this affects his work

Godehard Sutmann from the Jülich Supercomputing Center (JSC) then gave an introduction into methods for simulating dilute solutions of polymers while taking into account hydrodynamic interactions.

This was followed by a talk about an implementation of parts of the outlined algorithms by Annika Schiller (also JSC). For realizing her project she applied the BSC's superscalar framework for Cell.

Astronomy Morning

Honoring the year of astronomy, Tuesday's morning was dedicated to astronomy talks. Prof. Ibanez lead through the morning .

Miguel Angel Aloy tried to make plausible Why is it worth to spend 1.5 million CPU-hours in relativistic astrophysics.
Miguel Angel Aloy

Data processing of the GAIA mission is a challenging task. Xavier Luri of the University of Barcelona gave an interesting insight in how this challenge is going to be met.

Simulations of the inspiral and merger of unequal-mass neutron star binaries was the topic of José A. Font talk, who is from the Universidad de Valencia.

Finding interesting phenomena in cosmological simulation which can be used to understand observations is an important methodology in astrophysics.
Steffen Knollmann from the Universidad Autonoma de Madrid highlighted the various aspects of such analysis task on the basis of cosmological n-body simulations.

Relativistic hydrodynamic flows were simulated by Manuel Perucho from the Universidad de Valencia. He presented method and results on simulations of the interactions of hydrodynamic jets and stellar wind as well as the evolution of such jets.

The morning ended with a lively discussion on what users what like to see improved by hard- and software vendors including the tools providers from the various computing centers present.
Most of the concern dealt with the event of multicore processors exhibiting a large number of compute cores. Here, it was agreed that OpenMP/MPI hybrid codes seem to be the future interm of addressing the multicore challenge.
Nevertheless, various people pointed out that OpenMP/MPI hybridization is as a challenge in itself. Employing this kind of hybridization means for most applications a complete redesign of the (MPI-centric) application.

Furthermore, it was noted that the current I/O libraries suffer from various problems. The most prominent one is certainly the lack of support for high cpu numbers (>10000). Here, most libraries have limits which renders them unusable in a supercomputing context. But also better possibilities for handling large amounts of data in file systems was formulated as a demand to parallel filesystem vendors.

ScicomP 15 in Barcelona

About a hundred leading scientists and experts in the field of scientific computing are currently gathering in Barcelona. They are taking part in the IBM supported ScicomP meeting, addressing various aspects of porting and optimizing applications to IBM latest hardware systems. This year’s event is hosted and organized by the Barcelona Supercomputing Center (BSC).

The meeting started out with workshop and tutorial sessions on how to make efficient use of the PowerXCell Architecture which can also be found in the Playstation 3.
In addition, BSC offers daily tours showing mare nostrum, one of Europe’s fastes supercomputers. This supercomputer is very likely the first one which has been installed in a church.