Dennis Gannon - Dept. Computer Science - Indiana University
Title:Building Grid Applications and Portals:
An Approach Based on Components,
Web Services and Workflow Tools.
Date: 1 Sept.
Large scale Grid applications are often composed a distributed collection
of parallel simulation codes, instrument monitors, data miners, rendering
and visualization tools. For example, consider a severe storm prediction
system driven by a grid of weather sensors. Typically these applications
are very complex to build, so users interact with them through a Grid
portal front end. This talk outlines an approach based on a web service
component architecture for building these applications and portal
interfaces. We illustrate how the traditional parallel application can be
wrapped by a web service factory and integrated into complex workflows.
Additional issues that are addressed include: grid security, web service
tools and workflow composition tools. The talk will try to outline several
important classes of unsolved problems and possible new research
directions for building grid applications.
Some Techniques for Automated, Resource-Aware Distributed and
Mobile Computing in a Multi-Paradigm Programming System
Date: 3 Sept.
Distributed parallel execution systems speed up applications by
splitting tasks into processes whose execution is assigned to
different receiving nodes in a high-bandwidth network. On the
distributing side, a fundamental problem is grouping and scheduling
such tasks such that each one involves sufficient computational cost
when compared to the task creation and communication costs and other
such practical overheads. On the receiving side, an important issue
is to have some assurance of the correctness and characteristics of
the code received and also of the kind of load the particular task
is going to pose, which can be specified by means of certificates.
In this paper we present in a tutorial way a number of general
solutions to these problems, and illustrate them through their
implementation in the Ciao multi-paradigm language and program
development environment. This system includes facilities for
parallel and distributed execution, an assertion language for
specifying complex programs properties (including safety and
resource-related properties), and compile-time and run-time tools
for performing automated parallelization and resource control, as
well as certification of programs with resource consumption
assurances and efficient checking of such certificates.
Mateo Valero - DAC-UPC - Barcelona
Date: 1 Sept
A promising approach for dealing with very long latency memory accesses (cache
misses to main memory) is to dramatically increase the number of in-flight
instructions in an out-of-order processor. Current processors commit
instructions in program order. Consequently, a huge quantity of resources are
needed to maintain thousands of instructions in flight. We need to do research
in new techniques oriented to better use of resources. We observe that many
inefficiencies can be eliminated if we change the model of in order commit of
instructions. We need to design processors that support some form of
out-of-order commit of instructions. But, of course, we also need to maintain
To implement out-of-order instruction commit, we propose checkpointing a few
very specific instructions with the objective of reducing and managing all the
critical resources in the architecture such as ROB, Register File and
Instruction Queues. We apply checkpointing, for example, to long-latency load
instructions and/or hard-to-predict branch instructions. This mechanism of
In this talk, we will comment papers describing the previous
mechanisms and we will open new topics for research.
- makes the existence of the classical ROB unnecessary.
- allows release the resources in an aggressive way. For example,
strategic checkpointing allows an efficient implementation of early release and
allocation of registers.
- allows more intelligent management of the instruction queues.
Murray Cole - School of Informatics - Edinburgh UK
Title: Why structured parallel programming matters
Date: 3 Sept 2004
Simple parallel programming frameworks such as Pthreads, or the six function core of
MPI, are universal in the sense that they support the expression of arbitrarily
complex patterns of computation and interaction between concurrent activities.
Pragmatically, their descriptive power is constrained only by the programmer's
creativity and capacity for attention to detail.
Meanwhile, as our understanding of the structure of parallel algorithms
develops, it has become clear that many parallel
applications can be characterized and classified by their adherence to
one or more of a number of generic patterns.
For example, many diverse applications share the underlying control
and data flow of the pipeline paradigm, whether expressed in terms
of message passing, or by constrained access to shared data.
A number of research programs, using terms such as skeleton, template,
archetype and pattern, have sought to exploit this phenomenon
by allowing the programmer to explicitly express such meta-knowledge
in the program source, through the use of new libraries, annotations and control constructs,
rather than leaving it implicit in the interplay of more primitive universal mechanisms.
While early work stressed productivity and portability
(the programmer is no longer required to repeatedly
``reinvent the wheel'') we argue that the true significance of this approach lies in
the capture of complex algorithmic knowledge which would be impossible to determine by
static examination of an equivalent unstructured source.
This enables developments
in a number of areas. With respect to low-level performance,
it allows the run-time system, library code or compiler to make clever optimizations
based on detailed foreknowledge of the evolving computation. With respect to
high-level performance, it enables a methodology of
improvement through powerful restructuring transformations. Similarly, with
respect to program correctness, it allows arguments to be pursued at a
much coarser, more tractable grain than would otherwise be possible.
Last modified: Fri Nov 28 17:00:22 CET 2003