16999625
Memory Subsystem Characterization in a 16-Core Snoop-Based Chip-Multiprocessor Architecture
In this paper we present an exhaustive evaluation of the memory subsystem in a chip-multiprocessor (CMP) architecture composed of 16 cores. The characterization is performed making use of a new simulator that we have called DCMPSIM and extends the Rice Simulator for ILP Multiprocessors (RSIM) with the functionality required to model a contemporary CMP in great detail. 
 
To better understand the behavior of the memory subsystem, we propose a taxonomy of the L1 cache misses found in CMPs which subsequently we use to determine where the hot spots of the memory hierarchy are and, thus, where computer architects have to place special emphasis to improve the performance of future dense single-chip multiprocessors, which will integrate 16 or more processor cores.
9781969
CORBA Lightweight Components : A Model for Distributed Component-BasedHeterogeneous Computation
In this article we present CORBA Lightweight Components, CORBA-LC, a new network-centered reflective component model which allows building distributed applications assembling binary independent components spread on the network. It provides a peer network view in which the component dependencies are managed automatically to perform an intelligent application run-time deployment, leading to better utilization of resources. We show the validity of the CORBA-LC approach in dealing with CSCW and Grid Computing applications.
17330539
Automatic Code Generation for Non-Funtional Aspects in the CORBA-LC Component Model
Component Technology allows a better modularity and reusability of applications. Components are even better suited for the development of distributed applications, as those applications can be partitioned in terms of components installed and running (deployed) in the di erent hosts participating in the system. Components, apart from implementing their own functionality, have other requirements in term of non-functional aspects such as CPU power utilization, load balancing, fault-tolerance, etc. The code for ensuring these aspects can be automatically generated based on the requirements stated by components and applications, thus leveraging the component implementer of having to deal with these non-functional aspects. In this paper we present (1) architecture of the automatic code generator, and (2) the characteristics of the generated code for dealing with the aforementioned non-functional aspects in the context of CORBA LC.CORBA LC is a lightweight distributed re ective component model based on CORBA that imposes a peer network model in which the whole network acts as a repository for managing and assigning the whole set of resources: components, CPU cycles, memory, etc.
6582409
A Low Overhead Fault Tolerant Coherence Protocol for CMP Architectures
It is widely accepted that transient failures will appear more frequently in chips designed in the near future due to several factors such as the increased integration scale. On the other hand, chip-multiprocessors (CMP) that integrate several processor cores in a single chip are nowadays the best alternative to more efficient use of the increasing number of transistors that can be placed in a single die. Hence, it is necessary to design new techniques to deal with these faults to be able to build sufficiently reliable chip multiprocessors (CMPs). In this work, we present a coherence protocol aimed at dealing with transient failures that affect the interconnection network of a CMP, thus assuming that the network is no longer reliable. In particular, our proposal extends a token-based cache coherence protocol so that no data can be lost and no deadlock can occur due to any dropped message. Using GEMS full system simulator, we compare our proposal against a similar protocol without fault tolerance (TOKENCMP). We show that in absence of failures our proposal does not introduce overhead in terms of increased execution time over TOKENCMP. Additionally, our protocol can tolerate message loss rates much higher than those likely to be found in the real world without increasing execution time more than 15%
17271240
DualFS: a new journaling file system without meta-data duplication
In this paper we introduce DualFS, a new high performance journaling file system that puts data and meta-data on different devices (usually, two partitions on the same disk or on different disks), and manages them in very different ways. Unlike other journaling file systems, DualFS has only one copy of every meta-data block. This copy is in the meta-data device, a log which is used by DualFS both to read and to write meta-data blocks. By avoiding a time-expensive extra copy of meta-data blocks, DualFS can achieve a good performance as compared to other journaling file systems. Indeed, we have implemented a DualFS prototype, which has been evaluated with microbenchmarks and macrobenchmarks, and we have found that DualFS greatly reduces the total I/O time taken by the file system in most cases (up to 97%), whereas it slightly increases the total I/O time only in a few and limited cases.
1081050
An efficient implementation of a 3D wavelet transform based encoder on hyper-threading technology
Video medical compression algorithms based on the 3D wavelet transform obtain both excellent compression rates and very good quality, at the expense of a higher execution time. The goal of this work is to improve the execution time of our 3D Wavelet Transform Encoder. We examine and exploit the characteristics and advantages of a hyper-threading processor. The Intel Hyper-threading Technology (HT) is a technique based on simultaneous multi-threading (SMT), which allows several independent threads to issue instructions to multiple functional units in a single cycle. In particular, we present two approaches: data-domain and functional, which differ in the way that the decomposition of the application is performed. The first approach is based on data division, where the same task is performed simultaneously by each thread on an independent part of the data. In the second approach, the processing is divided in different tasks that are executed concurrently on the same data set. Based on the latter approach, we present three proposals that differ in the way that the tasks of the application are divided between the threads. Results show speedups of up to 7% and 34% by the data-domain and functional decomposition, respectively, over a version executed without hyper-threading technology. Finally, we design several implementations of the best method with Pthreads and OpenMP using functional decomposition. We compare them in terms of execution speed, ease of implementation and maintainability of the resulting code.
16750894
A Genetic Algorithm for Solving a Production and Delivery Scheduling Problem with Time Windows
This paper deals with the problem of selecting and scheduling a set of orders to be processed by a manufacturing plant and immediately delivered to the customer site. Constraints to be considered are the limited production capacity, the available number of vehicles and the time windows within which orders must be served. We describe the problem relating it to similar problems studied in the literature. A genetic algorithm to solve the problem is developed and tested empirically with randomly generated problems. Comparisons with an exact procedure and a tabu search procedure show that the method finds very good-quality solutions.
32636956
Viral System to Solve Optimization Problems: An Immune-Inspired Computational Intelligence Approach
This paper presents Viral System as a new immune-inspired computational intelligence approach to deal with optimization problems. The effectiveness of the approach is tested on the Steiner problem in networks a well known NP-Hard problem providing great quality solutions in the order of the best known approaches or even improving them.
7433683
Viral systems: A new bio-inspired optimisation approach
The paper presents a new approach to deal with combinatorial problems. It makes use of a biological analogy inspired by the performance of viruses. The replication mechanism, as well as the hosts' infection processes is used to generate a metaheuristic that allows the obtention of valuable results. The viral system (VS) theoretical context is described and it is applied to a library of medium-to-large-sized cases of the Steiner problem for which the optimal solution is known. The method is compared with the metaheuristics that have provided the best results for the Steiner problem. The VS provides better solutions than genetic algorithms and certain tabu search approaches. For the most sophisticated tabu search approaches (the best metaheuristic approximations to the Steiner problem solution) VS provides solutions of similar quality.