7148263
User-Friendly Methodology for Automatic Exploration of Compiler Options: A Case Study on the Intel XScale Microarchitecture
A duct adapter for use in conjunction with an air conditioning unit is disclosed. This adapter attaches to a discharge opening of an air conditioning unit and acts to divide the stream of conditioned air into multiple streams, one being discharged into the enclosure containing the air conditioning unit and a separate stream being discharged into a duct for delivery at a distant location. Means for attaching the adapter to the air conditioning unit and a damper assembly therein are additionally disclosed.
8575175
A User-Friendly Methodology for Automatic Exploration of Compiler Options
This paper introduces a practical methodology for automatic exploring compiler optimization options. The strategy behind this methodology is to provide an intelligent mechanism, in which the compiler will automatically identify optimized combination of compiler options for a given application. The decision made by the compiler is based on user requirements on what aspects of the generated code are the most critical for the compiled application through a specialized user interface. A set of pre-built databases of candidate optimized combinations of compiler options will help the compiler to make the right decision. This methodology will dramatically help users to get rid of the burden of fully understanding the compiler’s inner structure and organization to make the most profitable combination of options. All this work is taken by the compiler and the infrastructure proposed in this paper. This paper presents this methodology and describes its principles and technical mechanisms of the components.
206929170
Optimizing the Fast Fourier Transform on a Multi-core Architecture
The rapid revolution in microprocessor chip architecture due to multicore technology is presenting unprecedented challenges to the application developers as well as system software designers: how to best exploit the parallelism potential due to such multi-core architectures? In this paper, we report an in-depth study on such challenges based on our experience of optimizing the fast Fourier transform (FFT) on the IBM Cyclops-64 chip architecture - a large-scale multi-core chip architecture consisting 160 thread units, associated memory banks and an interconnection network that connect them together in a shared memory organization. We demonstrate how multi-core architectures like the C64 could be used to achieve a high performance implementation of FFT both in 1D and 2D cases. We analyze the optimization challenges and opportunities including problem decomposition, load balancing, work distribution, and data-reuse, together with the exploiting of the C64 architecture features such as the multi-level of memory hierarchy and large register files. Furthermore, the experience learned during the hand-tuned optimization process have provided valuable guidance in our compiler optimization design and implementation. The main contributions of this paper include: 1) our study demonstrates that successful optimization for C64-like large-scale multi-core architectures requires a careful analysis that can identify certain domain-specific features of a target application (e.g. FFT) and match them well with some key multi-core architecture features; 2) our optimization, assisted with hand-tuned process, provided quantitative evidence on the importance of each optimization identified in 1); 3) automatic optimization by our compiler, the design and implementation of which is guided by the feedbacks from 1) and 2), shows excellent results that are often comparable to the results derived from our time-consuming hand-tuned code.
4777365
Argos: Efficient Refresh in an XQL-Based Web Caching System
The Web has become a major conduit to information repositories of all kinds. Web caches are employed to store web views to provide an immediate response to recurring queries. However, the accuracy of the replicates in web caches encounters challenges due to the dynamicity of web data. We are thus developing and evaluating a web caching system equipped with an efficient refresh strategy. With the assistance of a novel index structure - the Aggregation Path Index (APIX), we built Argos, a web caching system based on the GMD XQL query engine. Argos achieves a high degree of self-maintenance by diagnosing irrelevant data update cases. It hence greatly improves the refresh performance of the materialized web view. We also report preliminary experimental results assessing the performance of Argos compared to the state-of-the-art solution in the literature.
3138071
Statistical relationship determination in automatic thesaurus construction
Statistical relationship determination among terms is one of the key issues in automatic thesaurus construction. We systematically analyze existing relevant approaches based on their underlying probabilistic assumptions, and propose a combined approach that overcomes their limitations.
17289553
On the complexity of the minimum and maximum global snapshot problems
Deriving the minimum and maximum global snapshots is very useful for some error detection problems in distributed programs. Several researchers, e.g., Groselj (1993) and Chen and Wu (1996), have shown that the minimum and maximum global snapshot problems are linear-time reducible to the maximum constant-ratio network flow (MCNF) problem, here defined as the well-known maximum network flow problem with m=/spl Theta/(n), where m is the number of edges and n is the number of vertices in the given flow network. The authors show in a reverse way that the MCNF problem is also linear-time reducible to these global snapshot problems. Thus, one can conclude that the global snapshot problems are "as difficult as" the MCNF problem in terms of time complexity.
7800069
Detection of summative global predicates
In distributed programs, we usually keep some global predicates from being satisfied to make it easy to run the programs correctly. A common type of global predicates are: the total number of certain tokens in the whole distributed system is always the same or in specific ranges. In this paper, we call this summative predicates, classified into the following four: (1) at some global state of the system, N/spl ne/K, (2) NK (or N/spl ges/K), and (4) N=K, where N is the total number of tokens and K is a constant. This paper investigates the methods of detecting various summative global predicates. The first class of summative predicates are trivial to detect by simply checking each message. For the second class of summative predicates, B. Groselj (1993) and V.K. Garg (1995) solved the problem by reducing the problem to a maximum network flow problem. In this paper, we propose an elegant technique, called normalization, to allow the second and third classes of summative predicates to be solved by also reducing the problem to a maximum network flow problem. For the fourth class of summative predicates, we prove that it is an NP-complete problem.
6721638
Adaptive video streaming in vertical handoff: a case study
Video streaming has become a popular form of transferring video over the Internet. With the emergence of mobile computing needs, a successful video streaming solution demands 1) uninterrupted services even with the presence of mobility and 2) adaptive video delivery according to current link properties. We study the need and evaluate the performance of adaptive video streaming in vertical handoff scenarios. We use universal seamless handoff architecture (USHA) to create a seamless handoff environment, and use the video transfer protocol (VTP) to adapt video streaming rates according to "eligible rate estimates". Using testbed measurements experiments, we verify the importance of service adaptation, as well as show the improvement of user-perceived video quality, via adapting video streaming in the vertical handoffs.