749 research outputs found
Remote observing with the Caltech millimeter-wave array
Remote observing with Caltech's millimeter wave array at the Owens Valley Radio Observatory (OVRO) is being extended to use the graphical capabilities commonly available on computers today. To allow the instrument to be clearly presented to the user, a rich interface has been developed that combines the use of color highlights, graphical representation of data, and audio. Java and internet protocols are used to extend this interface across the Web to provide remote access. Compression techniques are used to enable use over low bandwidth links. This paper presents the design goals, implementation details, and current status of this effort with emphasis on the monitoring of the array
ShareJIT: JIT Code Cache Sharing across Processes and Its Practical Implementation
Just-in-time (JIT) compilation coupled with code caching are widely used to
improve performance in dynamic programming language implementations. These code
caches, along with the associated profiling data for the hot code, however,
consume significant amounts of memory. Furthermore, they incur extra JIT
compilation time for their creation. On Android, the current standard JIT
compiler and its code caches are not shared among processes---that is, the
runtime system maintains a private code cache, and its associated data, for
each runtime process. However, applications running on the same platform tend
to share multiple libraries in common. Sharing cached code across multiple
applications and multiple processes can lead to a reduction in memory use. It
can directly reduce compile time. It can also reduce the cumulative amount of
time spent interpreting code. All three of these effects can improve actual
runtime performance.
In this paper, we describe ShareJIT, a global code cache for JITs that can
share code across multiple applications and multiple processes. We implemented
ShareJIT in the context of the Android Runtime (ART), a widely used,
state-of-the-art system. To increase sharing, our implementation constrains the
amount of context that the JIT compiler can use to optimize the code. This
exposes a fundamental tradeoff: increased specialization to a single process'
context decreases the extent to which the compiled code can be shared. In
ShareJIT, we limit some optimization to increase shareability. To evaluate the
ShareJIT, we tested 8 popular Android apps in a total of 30 experiments.
ShareJIT improved overall performance by 9% on average, while decreasing memory
consumption by 16% on average and JIT compilation time by 37% on average.Comment: OOPSLA 201
Proxy compilation for Java via a code migration technique
There is an increasing trend that intermediate representations (IRs) are used to deliver programs in more and more languages, such as Java. Although Java can provide many advantages, including a wider portability and better optimisation opportunities on execution, it introduces extra overhead by requiring an IR translation for the program execution. For maximum execution performance, an optimising compiler is placed in the runtime to selectively optimise code regions regarded as āhotspotsā. This common approach has been effectively deployed in many implementation of programming languages. However, the computational resources demanded by this approach made it less efficient, or even difficult to deploy directly in a resourceconstrained environment. One implementation approach is to use a remote compilation technique to support compilation during the execution. The work presented in this dissertation supports the thesis that execution performance can be improved by the use of efficient optimising compilation by using a proxy dynamic optimising compiler. After surveying various approaches to the design and implementation of remote compilation, a proxy compilation system called Apus is defined. To demonstrate the effectiveness of using a dynamic optimising compiler as a proxy compiler, a complete proxy compilation system is written based on a research-oriented Java VirtualMachine (JVM). The proxy compilation system is discussed in detail, showing how to deliver remote binaries and manage a cache of binaries by using a code migration approach. The proxy compilation client shows how the proxy compilation service is integrated with the selective optimisation system to maximise execution performance. The results of empirical measurements of the system are given, showing the efficiency of code optimisation from either the proxy compilation service and a local binary cache. The conclusion of this work is that Java execution performance can be improved by efficient optimising compilation with a proxy compilation service by using a code migration technique
PhotoRaptor - Photometric Research Application To Redshifts
Due to the necessity to evaluate photo-z for a variety of huge sky survey
data sets, it seemed important to provide the astronomical community with an
instrument able to fill this gap. Besides the problem of moving massive data
sets over the network, another critical point is that a great part of
astronomical data is stored in private archives that are not fully accessible
on line. So, in order to evaluate photo-z it is needed a desktop application
that can be downloaded and used by everyone locally, i.e. on his own personal
computer or more in general within the local intranet hosted by a data center.
The name chosen for the application is PhotoRApToR, i.e. Photometric Research
Application To Redshift (Cavuoti et al. 2015, 2014; Brescia 2014b). It embeds a
machine learning algorithm and special tools dedicated to preand
post-processing data. The ML model is the MLPQNA (Multi Layer Perceptron
trained by the Quasi Newton Algorithm), which has been revealed particularly
powerful for the photo-z calculation on the base of a spectroscopic sample
(Cavuoti et al. 2012; Brescia et al. 2013, 2014a; Biviano et al. 2013).
The PhotoRApToR program package is available, for different platforms, at the
official website (http://dame.dsf.unina.it/dame_photoz.html#photoraptor).Comment: User Manual of the PhotoRaptor tool, 54 pages. arXiv admin note:
substantial text overlap with arXiv:1501.0650
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