8973422
ESP: a language for programmable devices
This paper presents the design and implementation of Event-driven State-machines Programming (ESP)—a language for programmable devices. In traditional languages, like C, using event-driven state-machine forces a tradeoff that requires giving up ease of development and reliability to achieve high performance. ESP is designed to provide all of these three properties simultaneously.
ESP provides a comprehensive set of features to support development of compact and modular programs. The ESP compiler compiles the programs into two targets—a C file that can be used to generate efficient firmware for the device; and a specification that can be used by a verifier like SPlN to extensively test the firmware.
As a case study, we reimplemented VMMC firmware that runs on Myrinet network interface cards using ESP. We found that ESP simplifies the task of programming with event-driven state machines. It required an order of magnitude fewer lines of code than the previous implementation. We also found that model-checking verifiers like SPIN can be used to effectively debug the firmware. Finally, our measurements indicate that the performance overhead of using ESP is relatively small.
890006
Dynamic memory management for programmable devices
2904394
Physical simulation for animation and visual effects: parallelization and characterization for chip multiprocessors
We explore the emerging application area of physics-based simulation for computer animation and visual special effects. In particular, we examine its parallelization potential and characterize its behavior on a chip multiprocessor (CMP). Applications in this domain model and simulate natural phenomena, and often direct visual components of motion pictures. We study a set of three workloads that exemplify the span and complexity of physical simulation applications used in a production environment: fluid dynamics, facial animation, and cloth simulation. They are computationally demanding, requiring from a few seconds to several minutes to simulate a single frame; therefore, they can benefit greatly from the acceleration possible with large scale CMPs.
 Starting with serial versions of these applications, we parallelize code accounting for at least 96% of the serial execution time, targeting a large number of threads.We then study the most expensive modules using a simulated 64-core CMP.
 For the code representing key modules, we achieve parallel scaling of 45x, 50x, and 30x for fluid, face, and cloth simulations, respectively. The modules have a spectrum of parallel task granularity and locking behavior, and all but one are dominated by loop-level parallelism. Many modules operate on streams of data. In some cases, modules iterate over their data, leading to significant temporal locality. This streaming behavior leads to very high on-die and main memory bandwidth requirements. Finally, most modules have little inter-thread communication since they are data-parallel, but a few require heavy communication between data-parallel operations.
8714791
Hybrid transactional memory
High performance parallel programs are currently difficult to write and debug. One major source of difficulty is protecting concurrent accesses to shared data with an appropriate synchronization mechanism. Locks are the most common mechanism but they have a number of disadvantages, including possibly unnecessary serialization, and possible deadlock. Transactional memory is an alternative mechanism that makes parallel programming easier. With transactional memory, a transaction provides atomic and serializable operations on an arbitrary set of memory locations. When a transaction commits, all operations within the transaction become visible to other threads. When it aborts, all operations in the transaction are rolled back.Transactional memory can be implemented in either hardware or software. A straightforward hardware approach can have high performance, but imposes strict limits on the amount of data updated in each transaction. A software approach removes these limits, but incurs high overhead. We propose a novel hybrid hardware-software transactional memory scheme that approaches the performance of a hardware scheme when resources are not exhausted and gracefully falls back to a software scheme otherwise.
6728312
Evaluating synchronization on shared address space multiprocessors: methodology and performance
Synchronization is an area that exhibits rich hardware-software interactions in multiprocessors. It was studied extensively using microbenchmarks a decade ago. However, its performance implications are not well understood on modern systems or on real applications. We study the impact of synchronization primitives and algorithms on a modern, 64processor, hardware-coherent shared address space multiprocessor: the SGI Origin 2000. In addition to the actual results on a modern system, we examine the key methodological issues in studying synchronization, for both microbenchmarks and applications. We find that although the efficient hardware support (Fetch&Op) for synchronization provided on our machine usually helps lock and barrier microbenchmarks, it does not help in improving application performance when compared to good software algorithms that use the processor-provided LL-SC instructions. This is true even in applications that spend a significant amount of time in synchronization operations. More elaborate hardware support is unlikely to have a significant benefit either. From the applications’ perspective, it is usually the waiting time due to load imbalance or serialization that dominates synchronization time, not the overhead of the synchronization operations themselves, even in apparently balanced cases where the overhead may be expected to be substantial.
6762565
Compilation, architectural support, and evaluation of SIMD graphics pipeline programs on a general-purpose CPU
Graphics and media processing is quickly emerging to become one of the key computing workloads. Programmable graphics processors give designers extra flexibility by running a small program for each fragment in the graphics pipeline. We investigate low-cost mechanisms to obtain good performance for modern graphics programs on a general purpose CPU. We present a compiler that compiles SIMD graphics program and generates efficient code on a general purpose CPU. The generated code can process between 25-0.3 million vertices per second on a 2.2 GHz Intel Pentium/spl reg/ 4 processor for a group of typical graphics programs. We also evaluate the impact of three changes in the architecture and compiler. Adding support for new specialized instructions improves the performance of the programs by 27.4% on average. A novel compiler optimization called mask analysis improves the performance of the programs by 19.5% on average. Increasing the number of architectural SIMD registers from 8 to 16 registers significantly reduces the number of memory accesses due to register spills.
20172442
Scheduling Web Advertisements: A Note on the Minspace Problem
Free services to internet users are commonly available on many web sites e.g., Hotmail and Yahoo. For such sites, revenue generated from advertisements (hereafter also called “ads”) placed on the web pages is critical for survival. An effective way to schedule ads on web pages to optimize certain performance measures is an important problem that these sites need to address.In this note, we report improved approximation algorithms for the following problem: ads from a set of n ads A = {Ai,...,An} are to be placed on a web page during a planning horizon that is divided into N time intervals. In each time interval, ads are shown in a rectangular space called a slot. An ad Ai is specified by its size si and frequency wi and is to be scheduled in exactly wi slots. We are required to find a schedule that minimizes the maximum fullness among all the slots, where the fullness of a slot is the sum of the sizes of ads scheduled in that slot. Our results include (i) the first online algorithm with a performance bound of $$2 - \frac{1}{N}$$, and (ii) two offline algorithms with performance guarantees of $$1 + 1\frac{1}{\sqrt{2}}$$ and $$\frac{3}{2}$$, respectively. These bounds are significant improvements over those for previously known algorithms presented in Adler, Gibbons, and Matias (2002) and Dawande, Kumar, and Sriskandarajah (2003).
7470034
Recognition of human actions using moment based features and artificial neural networks
This paper presents performance of view-based approach in automated recognition of predefined hand and gross body actions using artificial neural network. This approach represents motion by a static grey scale image template computed by collapsing the temporal components into the cumulative image-difference of frames. The seven invariant Hu moments are used as the feature vectors. The performance of the system is tested in real time using feed forward multilayer perceptron (MLP) based on back propagation.
1282113
Discriminative Fields for Modeling Spatial Dependencies in Natural Images
In this paper we present Discriminative Random Fields (DRF), a discriminative framework for the classification of natural image regions by incorporating neighborhood spatial dependencies in the labels as well as the observed data. The proposed model exploits local discriminative models and allows to relax the assumption of conditional independence of the observed data given the labels, commonly used in the Markov Random Field (MRF) framework. The parameters of the DRF model are learned using penalized maximum pseudo-likelihood method. Furthermore, the form of the DRF model allows the MAP inference for binary classification problems using the graph min-cut algorithms. The performance of the model was verified on the synthetic as well as the real-world images. The DRF model outperforms the MRF model in the experiments.
17210903
Reconfigurable Instruction Set Extension for Enabling ECC on an 8-Bit Processor
Pervasive networks with low-cost embedded 8-bit processors are set to change our day-to-day life. Public-key cryptography provides crucial functionality to assure security which is often an important requirement in pervasive applications. However, it has been the hardest to implement on constraint platforms due to its very high computational requirements. This contribution describes a proof-of-concept implementation for an extremely low-cost instruction set extension using reconfigurable logic, which enables an 8-bit micro-controller to provide full size elliptic curve cryptography (ECC) capabilities. Introducing full size public-key security mechanisms on such small embedded devices will allow new pervasive applications. We show that a standard compliant 163-bit point multiplication can be computed in 0.113 sec on an 8-bit AVR micro-controller running at 4 Mhz with minimal extra hardware, a typical representative for a low-cost pervasive processor. Our design not only accelerates the computation by a factor of more than 30 compared to a software-only solution, it also reduces the code-size, data-RAM and power requirements.
1842198
On Deploying Wireless Sensors to Achieve Both Coverage and Connectivity
It is well-known that placing disks in the triangular lattice pattern is optimal for achieving full coverage on a plane. With the emergence of wireless sensor networks, however, it is now no longer enough to consider coverage alone when deploying a wireless sensor network; connectivity must also be con-sidered. While moderate loss in coverage can be tolerated by applications of wireless sensor networks, loss in connectivity can be fatal. Moreover, since sensors are subject to unanticipated failures after deployment, it is not enough to have a wireless sensor network just connected, it should be k-connected (for k > 1 ). In this paper, we propose an optimal deployment pattern to achieve both full coverage and 2-connectivity, and prove its optimality for all values of rc/rs, where rc is the communication radius, and rs is the sensing radius. We also prove the optimality of a previously proposed deployment pattern for achieving both full coverage and 1-connectivity, when rc/rs < √3 .Finally, we compare the efficiency of some popular regular deployment patterns such as the square grid and triangular lattice, in terms of the number of sensors needed to provide coverage and connectivity.