5 research outputs found
Characterizing traits of coordination
How can one recognize coordination languages and technologies? As this report
shows, the common approach that contrasts coordination with computation is
intellectually unsound: depending on the selected understanding of the word
"computation", it either captures too many or too few programming languages.
Instead, we argue for objective criteria that can be used to evaluate how well
programming technologies offer coordination services. Of the various criteria
commonly used in this community, we are able to isolate three that are strongly
characterizing: black-box componentization, which we had identified previously,
but also interface extensibility and customizability of run-time optimization
goals. These criteria are well matched by Intel's Concurrent Collections and
AstraKahn, and also by OpenCL, POSIX and VMWare ESX.Comment: 11 pages, 3 table
The essence of component-based design and coordination
Is there a characteristic of coordination languages that makes them
qualitatively different from general programming languages and deserves special
academic attention? This report proposes a nuanced answer in three parts. The
first part highlights that coordination languages are the means by which
composite software applications can be specified using components that are only
available separately, or later in time, via standard interfacing mechanisms.
The second part highlights that most currently used languages provide
mechanisms to use externally provided components, and thus exhibit some
elements of coordination. However not all do, and the availability of an
external interface thus forms an objective and qualitative criterion that
distinguishes coordination. The third part argues that despite the qualitative
difference, the segregation of academic attention away from general language
design and implementation has non-obvious cost trade-offs.Comment: 8 pages, 2 figures, 3 table
Optimizing for confidence - Costs and opportunities at the frontier between abstraction and reality
Is there a relationship between computing costs and the confidence people
place in the behavior of computing systems? What are the tuning knobs one can
use to optimize systems for human confidence instead of correctness in purely
abstract models? This report explores these questions by reviewing the
mechanisms by which people build confidence in the match between the physical
world behavior of machines and their abstract intuition of this behavior
according to models or programming language semantics. We highlight in
particular that a bottom-up approach relies on arbitrary trust in the accuracy
of I/O devices, and that there exists clear cost trade-offs in the use of I/O
devices in computing systems. We also show various methods which alleviate the
need to trust I/O devices arbitrarily and instead build confidence
incrementally "from the outside" by considering systems as black box entities.
We highlight cases where these approaches can reach a given confidence level at
a lower cost than bottom-up approaches.Comment: 11 pages, 1 figur
Machines are benchmarked by code, not algorithms
This article highlights how small modifications to either the source code of
a benchmark program or the compilation options may impact its behavior on a
specific machine. It argues that for evaluating machines, benchmark providers
and users be careful to ensure reproducibility of results based on the machine
code actually running on the hardware and not just source code. The article
uses color to grayscale conversion of digital images as a running example.Comment: 34 pages, 11 figures, 11 listings, 17 table