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Showing papers on "Overhead (computing) published in 1999"


Proceedings ArticleDOI
25 Feb 1999
TL;DR: A policy-enabled handoff system that allows users to express policies on what is the "best" wireless system at any moment, and make tradeoffs among network characteristics and dynamics such as cost, performance and power consumption is described.
Abstract: "Access is the killer app" is the vision of the Daedalus project at UC Berkeley. Being able to be connected seamlessly anytime anywhere to the best network still remains an unfulfilled goal. Often, even determining the "best" network is a challenging task because of the widespread deployment of overlapping wireless networks. We describe a policy-enabled handoff system that allows users to express policies on what is the "best" wireless system at any moment, and make tradeoffs among network characteristics and dynamics such as cost, performance and power consumption. We designed a performance reporting scheme estimating current network conditions, which serves as input to the policy specification. A primary goal of this work is to make it possible to balance the bandwidth load across networks with comparable performance. To avoid the problem of handoff instability, i.e., many mobile hosts making the same handoff decision at essentially the same time, we designed randomization into our mechanism. Given the current "best" network, our system determines whether the handoff is worthwhile based on the handoff overhead and potential network usage duration.

562 citations


01 Feb 1999
TL;DR: This document describes a method for compressing the headers of IP/UDP/RTP datagrams to reduce overhead on low-speed serial links.
Abstract: This document describes a method for compressing the headers of IP/UDP/RTP datagrams to reduce overhead on low-speed serial links. In many cases, all three headers can be compressed to 2-4 bytes.

558 citations


Journal ArticleDOI
TL;DR: In this article, a transmission line model for the simulation of electromagnetic transients in power systems is presented, which can be applied to both overhead lines and cables, even in the presence of a strongly frequency dependent transformation matrix and widely different modal time delays.
Abstract: This paper presents a transmission line model for the simulation of electromagnetic transients in power systems. The model can be applied to both overhead lines and cables, even in the presence of a strongly frequency dependent transformation matrix and widely different modal time delays. This has been achieved through a phase domain formulation where the modal characteristics have been utilized in the approximation for the propagation matrix. High computational efficiency is achieved by grouping modes with nearly equal velocities and by columnwise realization of the matrices for propagation and characteristic admittance.

539 citations


Posted Content
TL;DR: This paper proposes three cost-based heuristic algorithms: Volcano-SH and Volcano-RU, which are based on simple modifications to the Volcano search strategy, and a greedy heuristic that incorporates novel optimizations that improve efficiency greatly.
Abstract: Complex queries are becoming commonplace, with the growing use of decision support systems. These complex queries often have a lot of common sub-expressions, either within a single query, or across multiple such queries run as a batch. Multi-query optimization aims at exploiting common sub-expressions to reduce evaluation cost. Multi-query optimization has hither-to been viewed as impractical, since earlier algorithms were exhaustive, and explore a doubly exponential search space. In this paper we demonstrate that multi-query optimization using heuristics is practical, and provides significant benefits. We propose three cost-based heuristic algorithms: Volcano-SH and Volcano-RU, which are based on simple modifications to the Volcano search strategy, and a greedy heuristic. Our greedy heuristic incorporates novel optimizations that improve efficiency greatly. Our algorithms are designed to be easily added to existing optimizers. We present a performance study comparing the algorithms, using workloads consisting of queries from the TPC-D benchmark. The study shows that our algorithms provide significant benefits over traditional optimization, at a very acceptable overhead in optimization time.

336 citations


Proceedings ArticleDOI
Chen Ding1, Ken Kennedy1
01 May 1999
TL;DR: It is demonstrated that run-time program transformations can substantially improve computation and data locality and, despite the complexity and cost involved, a compiler can automate such transformations, eliminating much of the associated run- time overhead.
Abstract: With the rapid improvement of processor speed, performance of the memory hierarchy has become the principal bottleneck for most applications. A number of compiler transformations have been developed to improve data reuse in cache and registers, thus reducing the total number of direct memory accesses in a program. Until now, however, most data reuse transformations have been static---applied only at compile time. As a result, these transformations cannot be used to optimize irregular and dynamic applications, in which the data layout and data access patterns remain unknown until run time and may even change during the computation.In this paper, we explore ways to achieve better data reuse in irregular and dynamic applications by building on the inspector-executor method used by Saltz for run-time parallelization. In particular, we present and evaluate a dynamic approach for improving both computation and data locality in irregular programs. Our results demonstrate that run-time program transformations can substantially improve computation and data locality and, despite the complexity and cost involved, a compiler can automate such transformations, eliminating much of the associated run-time overhead.

232 citations


Proceedings ArticleDOI
06 Jul 1999
TL;DR: Simulation results show substantial performance improvements in terms of throughput, registration overhead, lost and duplicate packets during a handoff, without restrictions on physical placement of foreign agents.
Abstract: Mobile IP provides mobility support for hosts connected to the Internet without changing their IP addresses. Route optimization strategies complement Mobile IP, to alleviate triangle routing, by informing correspondent hosts of the mobile host's care-of address. We propose further strategies that are compatible with route optimization and its security model. First, foreign agents buffer packets for a mobile host and send them to its new location when it leaves. Second, hierarchical foreign agent management reduces the administrative overhead of frequent local handoffs, using an extension of the Mobile IP registration process so security can be maintained. Duplicate packets due to buffer handover are eliminated with the cooperation of mobile hosts. Simulation results show substantial performance improvements in terms of throughput, registration overhead, lost and duplicate packets during a handoff, without restrictions on physical placement of foreign agents.

226 citations


Book
01 Jun 1999
TL;DR: This work presents new algorithms to incrementally refresh a view during deferred maintenance, and shows that, with the proper choice of auxiliary tables, it is possible to lower both per-transaction overhead and view refresh time.
Abstract: Materialized views and view maintenance are important for data warehouses, retailing, banking, and billing applications. We consider two related view maintenance problems: 1) how to maintain views after the base tables have already been modified, and 2) how to minimize the time for which the view is inaccessible during maintenance.Typically, a view is maintained immediately, as a part of the transaction that updates the base tables. Immediate maintenance imposes a significant overhead on update transactions that cannot be tolerated in many applications. In contrast, deferred maintenance allows a view to become inconsistent with its definition. A refresh operation is used to reestablish consistency. We present new algorithms to incrementally refresh a view during deferred maintenance. Our algorithms avoid a state bug that has artificially limited techniques previously used for deferred maintenance.Incremental deferred view maintenance requires auxiliary tables that contain information recorded since the last view refresh. We present three scenarios for the use of auxiliary tables and show how these impact per-transaction overhead and view refresh time. Each scenario is described by an invariant that is required to hold in all database states. We then show that, with the proper choice of auxiliary tables, it is possible to lower both per-transaction overhead and view refresh time.

214 citations


Proceedings ArticleDOI
01 Nov 1999
TL;DR: A compact and fast hybrid signature scheme that can be used to solve the problem of packet source authentication for multicast and which can be viewed as an improvement to off-line/on-line signature schemes.
Abstract: This paper proposes a compact and fast hybrid signature scheme that can be used to solve the problem of packet source authentication for multicast. This scheme can be viewed as an improvement to off-line/on-line signature schemes, in that the signature size overhead is much smaller. Since this is a generic technique, it should have applications to several other practical problems as well.

200 citations


Journal ArticleDOI
TL;DR: A new family of edge-triggered flip-flops has been developed that has the capability of easily incorporating logic functions with a small delay penalty, and greatly reduces the pipeline overhead.
Abstract: In an attempt to reduce the pipeline overhead, a new family of edge-triggered flip-flops has been developed. The flip-flops belong to a class of semidynamic and dynamic circuits that can interface to both static and dynamic circuits. The main features of the basic design are short latency, small clock load, small area, and a single-phase clock scheme. Furthermore, the flip-flop family has the capability of easily incorporating logic functions with a small delay penalty. This feature greatly reduces the pipeline overhead, since each flip-flop can be viewed as a special logic gate that serves as a synchronization element as well.

167 citations


Journal ArticleDOI
TL;DR: The programmable BIST design presented here supports various test modes using a simple controller and built-in self-diagnosis by feeding error information to the external tester, and can test for critical timing faults, reducing tester time for ac parametric test.
Abstract: The programmable BIST design presented here supports various test modes using a simple controller. With the March C algorithm, the BIST circuit's overhead is under 1.3% for a 1-Mbit DRAM and under 0.3% for a 16-Mbit DRAM. The BIST design presented for embedded DRAM supports built-in self-diagnosis by feeding error information to the external tester. Moreover, using a specific test sequence, it can test for critical timing faults, reducing tester time for ac parametric test. The design supports wafer test, pre-burn-in test, burn-in, and final test. It is field-programmable; the user can program test algorithms using predetermined test elements (such as march elements, surround test elements, and refresh modes). The user can optimize the hardware for a specific embedded DRAM with a set of predetermined test elements. Our design is different from the microprogram-controlled BIST described by J. Dreibelbis et al. (1998) which has greater flexibility but higher overhead. Because our design begins at the register-transfer language level, test element insertion (for higher test coverage) and deletion (for lower hardware overhead are relatively easy.

135 citations


Patent
18 Feb 1999
TL;DR: In this article, the authors proposed techniques to include or incorporate return information (data) in an acknowledgement message after an incoming message has been successfully received from a sender in a Global System for Mobile Communications (GSM) network.
Abstract: Techniques that enable wireless client devices to more efficiently utilize available transmission bandwidth in a wireless network are disclosed. In one embodiment, the techniques operates to include or incorporate return information (data) in an acknowledgement message after an incoming message has been successfully received from a sender. As a result, messages are able to be effectively sent over the wireless network with less overhead. The techniques are particularly suitable for a Global System for Mobile Communications (GSM) network that is capable of bi-directional communications with a short message service center (SMSC).

Book ChapterDOI
TL;DR: This study constitutes the first extensive, though not exhaustive, experimental comparison of access structures for spatiotemporal data and finds out that the HR-tree usually outperforms the other candidates, in terms of query processing cost, specially when querying time points and small time intervals.
Abstract: Several applications require management of data which is spatially dynamic, e.g., tracking of battle ships or moving cells in a blood sample. The capability of handling the temporal aspect, i.e., the history of such type of data, is also important. This paper presents and evaluates three temporal extensions of the R-tree, the 3D R-tree, the 2+3 R-tree and the HR-tree, which are capable of indexing spatiotemporal data. Our experiments focus on discretely moving points (i.e., points standing at a specific location for a time period and then moving "instantaneously", and so on and so forth). We explore several parameters, e.g., initial spatial distribution, spatial query area and temporal query length. We found out that the HR-tree usually outperforms the other candidates, in terms of query processing cost, specially when querying time points and small time intervals. However, the main side effect of the HR-tree is its storage requirement, which is much larger than that of the other approaches. To reduce that, we explore a batch oriented updating approach, at the cost of some overhead during query processing time. To our knowledge, this study constitutes the first extensive, though not exhaustive, experimental comparison of access structures for spatiotemporal data.

Proceedings ArticleDOI
24 Oct 1999
TL;DR: A piecewise mapping function according to human visual sensitivity of contrast is used so that adaptivity can be achieved without extra bits for overhead in the embedding of multimedia data into a host image.
Abstract: We propose in this paper a novel method for embedding multimedia data (including audio, image, video, or text; compressed or non-compressed) into a host image. The classical LSB concept is adopted, but with the number of LSBs adapting to pixels of different graylevels. A piecewise mapping function according to human visual sensitivity of contrast is used so that adaptivity can be achieved without extra bits for overhead. The leading information for data decoding is few, no more than 3 bytes. Experiments show that a large amount of bit streams (nearly 30%-45% of the host image) can be embedded without sever degradation of the image quality (33-40 dB, depending on the volume of embedded bits).

Posted Content
TL;DR: This paper proposes an efficient example sampling method for example-based word sense disambiguation systems, characterized by the reliance on the notion of training utility: the degree to which each example is informative for future example sampling when used for the training of the system.
Abstract: This paper proposes an efficient example sampling method for example-based word sense disambiguation systems. To construct a database of practical size, a considerable overhead for manual sense disambiguation (overhead for supervision) is required. In addition, the time complexity of searching a large-sized database poses a considerable problem (overhead for search). To counter these problems, our method selectively samples a smaller-sized effective subset from a given example set for use in word sense disambiguation. Our method is characterized by the reliance on the notion of training utility: the degree to which each example is informative for future example sampling when used for the training of the system. The system progressively collects examples by selecting those with greatest utility. The paper reports the effectiveness of our method through experiments on about one thousand sentences. Compared to experiments with other example sampling methods, our method reduced both the overhead for supervision and the overhead for search, without the degeneration of the performance of the system.

Journal ArticleDOI
TL;DR: This paper presents an effective 3D compression scheme for interactive visualization of very large volume data, that exploits the power of wavelet theory and minimizes the overhead caused during run‐time reconstruction of voxel values.
Abstract: Interactive visualization of very large volume data has been recognized as a task requiring great effort in a variety of science and engineering fields. In particular, such data usually places considerable demands on run-time memory space. In this paper, we present an effective 3D compression scheme for interactive visualization of very large volume data, that exploits the power of wavelet theory. In designing our method, we have compromised between two important factors: high compression ratio and fast run-time random access ability. Our experimental results on the Visual Human data sets show that our method achieves fairly good compression ratios. In addition, it minimizes the overhead caused during run-time reconstruction of voxel values. This 3D compression scheme will be useful in developing many interactive visualization systems for huge volume data, especially when they are based on personal computers or workstations with limited memory.

Patent
09 Sep 1999
TL;DR: In this article, a method and system for compensating for instrumentation overhead in trace data by computing average minimum event times is provided, where the program is executed to generate trace records that are written to a trace file, and the trace events are represented as one or more nodes in a tree data structure.
Abstract: A method and system for compensating for instrumentation overhead in trace data by computing average minimum event times is provided. In order to profile a program, the program is executed to generate trace records that are written to a trace file. A set of trace event records are processed, and the trace events are represented as one or more nodes in a tree data structure. One or more performance statistics are stored at each node in the tree data structure, and a performance statistic at each node is processed to determine an overhead compensation value. The overhead compensation value is determined by computing a local overhead value for each node in the tree data structure. The total execution time of a routine corresponding to the event represented by the node is retrieved, and the local overhead value is computed as the average of the execution time over the number of calls to the routine and the number of calls from the routine to other routines. The minimum of all of the local overhead values is the maximum possible global value used as the overhead compensation value. The overhead compensation value is then applied to the performance statistic at each node.

Journal ArticleDOI
TL;DR: A multitiered performance analysis methodology consisting of a mix of static simulations, dynamic simulations at different time scales, and analytic methods to address the various feasibility issues: impact on coverage; capacity; power control; and effectiveness of burst admission algorithms is proposed.
Abstract: The advantages of code division multiple access (CDMA) for cellular voice have become well known, and IS-95-based systems have now been widely deployed. Attention is now focused on higher data-rate packet services for cellular systems. Although many packet multiple access schemes have been studied over the years, researchers have often studied single cell performance and ignored reuse. Moreover, direct sequence spread spectrum (DSSS) has been considered unsuitable for high data-rate packet multiple access since spreading limits the permitted data rates, DSSS requires large overhead (preambles) for acquisition and requires closed-loop power control. In this paper, we describe a scheme for high data-rate packet service using CDMA that addresses all of the above problems and has been standardized in Revision B of IS-95. A low rate fundamental code channel is maintained that eliminates the need for long preamble and provides closed-loop power control. Reuse is managed by the infrastructure through a "burst-level" admission control based on load and interference-level measurements at the base stations and mobiles. We report on the feasibility of such a burst-mode packet data service for cellular CDMA networks. The focus is not only on the performance of high data-rate users, but also on the impact on voice users sharing the CDMA band. We propose a multitiered performance analysis methodology consisting of a mix of static simulations, dynamic simulations at different time scales, and analytic methods to address the various feasibility issues: impact on coverage; capacity; power control; and effectiveness of burst admission algorithms. Based on the current study, we can conclude that the proposed approach is well suited for third-generation wideband CDMA systems being considered for standardization throughout the world.

Journal ArticleDOI
TL;DR: In this paper, a periodically excited single-degree-of-freedom (SDOF) model of a combined pantograph-catenary system is introduced and its basic dynamic behaviour is discussed.

Proceedings ArticleDOI
26 Apr 1999
TL;DR: This technique uses a special Programmable Address Decoder (PAD) to disable faulty blocks and to re-map their references to healthy blocks to overcomes the rapid degradation of performance as the number of faults increases.
Abstract: This paper presents a new fault-tolerance technique for cache memories. Current fault-tolerance techniques for caches are limited either by the number of faults that can be tolerated or by the rapid degradation of performance as the number of faults increases. In this paper, we present a new technique that overcomes these two problems. This technique uses a special Programmable Address Decoder (PAD) to disable faulty blocks and to re-map their references to healthy blocks. Simulation results show that the performance degradation of direct-mapped caches with PAD is smaller than the previous techniques. However, for set-associative caches, the overhead of PAD is primarily advantageous if a relatively large number of faults is to be tolerated. The area overhead was estimated at about 10% of the overall cache area for a hypothetical design and is expected to be less for actual designs. The access time overhead is negligible.

Journal ArticleDOI
TL;DR: It is shown that a threshold result still exists in three, two, or one spatial dimensions when next-to-nearest-neighbour gates are available, and explicit constructions are presented.
Abstract: I discuss how to perform fault-tolerant quantum computation with concatenated codes using local gates in small numbers of dimensions. I show that a threshold result still exists in three, two, or one dimensions when next-to-nearest-neighbor gates are available, and present explicit constructions. In two or three dimensions, I also show how nearest-neighbor gates can give a threshold result. In all cases, I simply demonstrate that a threshold exists, and do not attempt to optimize the error correction circuit or determine the exact value of the threshold. The additional overhead due to the fault-tolerance in both space and time is polylogarithmic in the error rate per logical gate.

01 Jan 1999
TL;DR: Evidence is presented to show that hybrids can combine the virtues of both schemes and offer competitive performance, and it is argued that a hybrid can better avoid the devils that are the downfall of the separate alternatives.
Abstract: Remembered sets and dirty bits have been proposed as alternative implementations of the write barrier for garbage collection. There are advantages to both approaches. Dirty bits can be efficiently maintained with minimal, bounded overhead per store operation, while remembered sets concisely, and accurately record the necessary information. Here we present evidence to show that hybrids can combine the virtues of both schemes and offer competitive performance. Moreover, we argue that a hybrid can better avoid the devils that are the downfall of the separate alternatives.

Proceedings ArticleDOI
22 Feb 1999
TL;DR: It is shown how the traditional techniques for implementing page-based DSMs can be extended to control the sharing granularity in a flexible way, even when the size of the sharing unit varies, and is smaller than the operating system's page size.
Abstract: In this paper we develop a novel technique, called MULTIVIEW, which enables implementation of page-based fine-grain DSMs. We show how the traditional techniques for implementing page-based DSMs can be extended to control the sharing granularity in a flexible way, even when the size of the sharing unit varies, and is smaller than the operating system's page size. The run-time overhead imposed in the proposed technique is negligible. We present a DSM system, called MILLIPAGE, which builds upon MULTIVIEW in order to support sharing in variable-size units. MILLIPAGE efficiently implements Sequential Consistency and shows comparable (sometimes superior) performance to related systems which use relaxed consistency models. It uses standard user-level operating system API and requires no compiler intervention, page twinning, diffs, code instrumentation, or sophisticated protocols. The resulting system is a thin software layer consisting mainly of a simple, clean protocol that handles page-faults.

Patent
Carl Binding1, Stefan G. Hild1, Luke O'Connor1, Sandeep K. Singhal1, Victor Shoup1, Michael Steiner1 
12 Oct 1999
TL;DR: Piggy-Backed key exchange as mentioned in this paper is a key exchange protocol that piggy-backs the key exchange onto other already-required messages (such as a client's HTTP GET request, or the server's response thereto) to minimize the overhead associated with setting up a secure browser-to-server connection.
Abstract: A method, system, and computer program product for establishing security parameters that are used to exchange data on a secure connection A piggy-backed key exchange protocol is defined, with which these security parameters are advantageously exchanged By piggy-backing the key exchange onto other already-required messages (such as a client's HTTP GET request, or the server's response thereto), the overhead associated with setting up a secure browser-to-server connection is minimized This technique is defined for a number of different scenarios, where the client and server may or may not share an encoding scheme, and is designed to maintain the integrity of application layer communication protocols In one scenario, a client and a server exchange secure messages using a trusted third party

Patent
15 Oct 1999
TL;DR: In this paper, a method for allocating and reallocating channelization codes to new and existing channels in a way that makes the maximum number of codes available at a given time for channels of different rates and different spreading factors was proposed.
Abstract: In spread spectrum communications, a method for allocating and re-allocating channelization codes to new and existing channels in a way that makes the maximum number of codes available at a given time for channels of different rates and different spreading factors. If re-allocations are not performed, a communication system employing the invention has a higher capacity than a system employing a random allocation strategy. The invention also reduces signaling overhead for re-allocations in comparison to a random allocation strategy because fewer re-allocations are necessary.

Proceedings ArticleDOI
21 Mar 1999
TL;DR: This work derives estimators and bounds that drive probabilistic polling algorithms for the estimation of the session size, n, of any potentially large scale multicast session from the binomial (n,p) distribution.
Abstract: We derive estimators and bounds that drive probabilistic polling algorithms for the estimation of the session size, n, of any potentially large scale multicast session. We base our analysis upon a mapping of polling mechanisms to the problem of estimating the parameter n of the binomial (n,p) distribution. From the binomial model, we derive an interval estimator for n, and we characterize the tradeoff between the estimator's quality and its overhead in a manner readily matched to application requirements. We derive other estimators and bounds that enable applications to treat as a tunable parameter the confidence that they will not exceed their overhead limits. We also suggest revised estimators and other improvements for the mechanisms proposed by Bolot, Turletti and Wakeman (1994), and Nonnenmacher and Biersack (see Proceedings of IEEE INFOCOM '98, Los Alamitos, California, IEEE Computer Society Press, 1998).

Proceedings Article
18 Jul 1999
TL;DR: A new scheduling algorithm for parallel single-agent search, transposition table driven work scheduling, that places the transpositiontable at the heart of the parallel work scheduling and achieves nearly-optimal performance.
Abstract: This paper introduces a new scheduling algorithm for parallel single-agent search, transposition table driven work scheduling, that places the transposition table at the heart of the parallel work scheduling. The scheme results in less synchronization overhead, less processor idle time, and less redundant search effort. Measurements on a 128-processor parallel machine show that the scheme achieves nearly-optimal performance and scales well. The algorithm performs a factor of 2.0 to 13.7 times better than traditional work-stealing-based schemes.

Proceedings ArticleDOI
01 May 1999
TL;DR: This paper introduces the concept of "mutable checkpoint," which is neither a tentative checkpoint nor a permanent checkpoint, to design efficient checkpointing algorithms for mobile computing systems and presents techniques to minimize the number of mutable checkpoints.
Abstract: Mobile computing raises many new issues such as lack of stable storage, low bandwidth of wireless channel, high mobility, and limited battery life. These new issues make traditional checkpointing algorithms unsuitable. Coordinated checkpointing is an attractive approach for transparently adding fault tolerance to distributed applications since it avoids domino effects and minimizes the stable storage requirement. However, it suffers from high overhead associated with the checkpointing process in mobile computing systems. Two approaches have been used to reduce the overhead: First is to minimize the number of synchronization messages and the number of checkpoints; the other is to make the checkpointing process nonblocking. These two approaches were orthogonal previously until the Prakash-Singhal algorithm (28) combined them. However, we (8) found that this algorithm may result in an inconsistency in some situations and we proved that there does not exist a nonblocking algorithm which forces only a minimum number of processes to take their checkpoints. In this paper, we introduce the concept of "mutable checkpoint," which is neither a tentative checkpoint nor a permanent checkpoint, to design efficient checkpointing algorithms for mobile computing systems. Mutable checkpoints can be saved anywhere, e.g., the main memory or local disk of MHs. In this way, taking a mutable checkpoint avoids the overhead of transferring large amounts of data to the stable storage at MSSs over the wireless network. We present techniques to minimize the number of mutable checkpoints. Simulation results show that the overhead of taking mutable checkpoints is negligible. Based on mutable checkpoints, our nonblocking algorithm avoids the avalanche effect and forces only a minimum number of processes to take their checkpoints on the stable storage.

Proceedings ArticleDOI
Michinobu Nakao1, Seiji Kobayashi1, Kazumi Hatayama1, K. Iijima1, S. Terada1 
28 Sep 1999
TL;DR: Efficient test point selection algorithms, which are suitable for utilizing overhead reduction approaches such as restricted cell replacement, test point flip-flops sharing, are proposed to meet the above requirements.
Abstract: This paper presents a practical test point insertion method for scan-based BIST. To apply test point insertion in actual LSIs, especially high performance LSIs, it is important to reduce the delay penalty and the area overhead of the inserted test points. Here efficient test point selection algorithms, which are suitable for utilizing overhead reduction approaches such as restricted cell replacement, test point flip-flops sharing, are proposed to meet the above requirements. The effectiveness of the algorithms is demonstrated by some experiments.

Proceedings ArticleDOI
21 Apr 1999
TL;DR: New compression algorithms for FPGA configurations that can significantly reduce this overhead are developed, which results in a single compression methodology which achieves higher compression ratios than existing algorithms in an off-line version, as well as a somewhat lower quality compression approach for on-line use in dynamic circuit generation and other mapping-time critical situations.
Abstract: The time it takes to reconfigure FPGAs can be a significant overhead for reconfigurable computing. In this paper we develop new compression algorithms for FPGA configurations that can significantly reduce this overhead. By using runlength and other compression techniques, files can be compressed by a factor of 3.6 times. Bus transfer and decompression hardware are also discussed. This results in a single compression methodology which achieves higher compression ratios than existing algorithms in an off-line version, as well as a somewhat lower quality compression approach which is suitable for on-line use in dynamic circuit generation and other mapping-time critical situations.

Journal ArticleDOI
TL;DR: This paper presents an index-based checkpointing algorithm for distributed systems with the aim of reducing the total number of checkpoints while ensuring that each checkpoint belongs to at least one consistent global checkpoint (or recovery line).
Abstract: This paper presents an index-based checkpointing algorithm for distributed systems with the aim of reducing the total number of checkpoints while ensuring that each checkpoint belongs to at least one consistent global checkpoint (or recovery line). The algorithm is based on an equivalence relation defined between pairs of successive checkpoints of a process which allows us, in some cases, to advance the recovery line of the computation without forcing checkpoints in other processes. The algorithm is well-suited for autonomous and heterogeneous environments, where each process does not know any private information about other processes and private information of the same type of distinct processes is not related (e.g., clock granularity, local checkpointing strategy, etc.). We also present a simulation study which compares the checkpointing-recovery overhead of this algorithm to the ones of previous solutions.