10316420
Balancing push and pull for data broadcast
The increasing ability to interconnect computers through internet-working, wireless networks, high-bandwidth satellite, and cable networks has spawned a new class of information-centered applications based on data dissemination. These applications employ broadcast to deliver data to very large client populations. We have proposed the Broadcast Disks paradigm [Zdon94, Acha95b] for organizing the contents of a data broadcast program and for managing client resources in response to such a program. Our previous work on Broadcast Disks focused exclusively on the “push-based” approach, where data is sent out on the broadcast channel according to a periodic schedule, in anticipation of client requests. In this paper, we study how to augment the push-only model with a “pull-based” approach of using a backchannel to allow clients to send explicit requests for data to the server. We analyze the scalability and performance of a broadcast-based system that integrates push and pull and study the impact of this integration on both the steady state and warm-up performance of clients. Our results show that a client backchannel can provide significant performance improvement in the broadcast environment, but that unconstrained use of the backchannel can result in scalability problems due to server saturation. We propose and investigate a set of three techniques that can delay the onset of saturation and thus, enhance the performance and scalability of the system.
7889988
Crash recovery in client-server EXODUS
In this paper, we address the correctness and performance issues that arise when implementing logging and crash recovery in a page-server environment. The issues result from two characteristics of page-server systems: 1) the fact that data is modified and cached in client database buffers that are not accessible by the server, and 2) the performance and cost trade-offs that are inherent in a client-server environment. We describe a recovery system that we have implemented for the client-server version of the EXODUS storage manager. The implementation supports efficient buffer management policies, allows flexibility in the interaction between clients and the server, and reduces the server load by generating log records at clients. We also present a preliminary performance analysis of the implementation.
2033914
Data Staging for On-Demand Broadcast
:A>@<b_DCGAdPBEG>R<:c\A8:Q@L]J.A8<0H(L[MOz:CTL0PBc:zbP[<bc4EGADCG ? >@_DA8EHGbP[HP[CTA>@<::ADCTAD<.HTQRJz:CTL0PBcb_DPBEwHw_DPBbP[zbQRA bP0EqPBc\A>Uc\ADPBCGAdP$c:P]HFP z:CGL.PBc:_8PBEwHP[<P]HGHGCFPB_ HG>@?BA4c:P]HFP c\A8QR>@?BA8CGJ P[QRHGA8CG<kP]HG>@?BA2MSLBCQ@PBCG0A&_Q@>RA8<.H  LB:a:QUP]HT>RL0<bE8`v:ADCTAbP0Evz ADAD<Ew>@B<:>Rk_8P[<.HvyL0CGZ HGL]P[CFc:EOc\A8?BA8QRL0:>R<b$LB<\QR>@<:Az:CTL0P0c:_DP0EKHET_F:Adc\a:QR >@<:P[Q@BLBCT>RHG:E MSLBCEGJ\EKHTADE :ADCTA!P[Q@Q c:P]HFP >RHGADEOPBCGAyCGAdPBc\>@QRJPY?]PB>RQUP[z:Q@A>@<¡HG:AEGADCT?BADCd¢ E6P[>@< ADLBCTJB` :A8EGA£EwHGabc:>RAdE(>@B<bLBCTA HG:Ac:P]HFP2P[<: P[0ADAD<.H>UETEwa:AdEOHTbP]HP[CT>@EGA:A8<HG:A c:P[HTP HTL£z A z:CTL0P0c:_DP0EKH£akEKH&z A L0z\HTPB>R<bA8c MSCGL0¤EGA8_DLB<bcbP[CTJ EwHGLBCFP[0A LBC,CTADL[HTA Q@L\_DP]HT>RL0<bE8`¥<¦HT:>@E4bPBkA8C8V  A§:CTLB L0EGA HG:CTADA_LB:Q@ADA8<0HFP[CTJ ̈EGLBQ@a\HG>@LB<kE HGL EGab_F ̈©Ba[«a ¬­«aD®B ̄±°.®_L0<b_A8CG<kED2§L0: LBCGHGa:<:>UEw HG>U_ ET_F:A8c:a:QR>@<:kVEGADCT?BA8C2_DP0_F:>R<bbVP[<bc bCGADMSAHT_F: >@<:b`&bA8EGAHGA8_Fb<:>@3.a:AdE$A ́\:Q@LB>RH:>@<.HTE$:CTL]? >@c:A8c z J,HG:AET_F:A8c\abQR>@<:,P[Q@BLBCT>RHG:,`$μ¶c:AHTPB>RQ@A8c kA8Cw MSLBCTP[<b_DA AD?]P[Q@abP]HT>RL0< akEw>@<:P[<·¥K ̧o1 a:QRHG>U_DPBEwHw zbP0EwAdc HGAdEKHTzkAdc EG:L]vE$HTbP]HHG:AdEwA4c:P]HFP EwHTPBB>@<: HGAd_F:<:>U3.a:A8Ev_8P[< c\CFP[P]HT>@_8P[Q@QRJA8<:bPB<b_A HT:A$kA8Cw MSLBCTP[<b_DA L[M£P Q@PBCG0AEG_8P[Q@A,LB<\c\ADPB<bcz:CTL0P0c  _DP0EKHvEGJ\EKHTAD,`
2567437
Dynamic Query Operator Scheduling for Wide-Area Remote Access
Distributed databases operating over wide-area networks such as the Internet, must deal with the unpredictable nature of the performance of communication. The response times of accessing remote sources can vary widely due to network congestion, link failure, and other problems. In such an unpredictable environment, the traditional iterator-based query execution model performs poorly. We have developed a class of methods, called query scrambling, for dealing explicitly with the problem of unpredictable response times. Query scrambling dynamically modifies query execution plans on-the-fly in reaction to unexpected delays in data access. In this paper we focus on the dynamic scheduling of query operators in the context of query scrambling. We explore various choices for dynamic scheduling and examine, through a detailed simulation, the effects of these choices. Our experimental environment considers pipelined and non-pipelined join processing in a client with multiple remote data sources and delayed or possibly bursty arrivals of data. Our performance results show that scrambling rescheduling is effective in hiding the impact of delays on query response time for a number of different delay scenarios.
2815522
Efficient Filtering of XML Documents for Selective Dissemination of Information
Information Dissemination applications are gaining increasing popularity due to dramatic improvements in communications bandwidth and ubiquity. The sheer volume of data available necessitates the use of selective approaches to dissemination in order to avoid overwhelming users with unnecessaryinformation. Existing mechanisms for selective dissemination typically rely on simple keyword matching or “bag of words” information retrieval techniques. The advent of XML as a standard for information exchangeand the development of query languages for XML data enables the development of more sophisticated filtering mechanisms that take structure information into account. We have developed several index organizations and search algorithms for performing efficient filtering of XML documents for large-scale information dissemination systems. In this paper we describe these techniques and examine their performance across a range of document, workload, and scale scenarios.
1006062
The design of an acquisitional query processor for sensor networks
We discuss the design of an acquisitional query processor for data collection in sensor networks. Acquisitional issues are those that pertain to where, when, and how often data is physically acquired (sampled) and delivered to query processing operators. By focusing on the locations and costs of acquiring data, we are able to significantly reduce power consumption over traditional passive systems that assume the a priori existence of data. We discuss simple extensions to SQL for controlling data acquisition, and show how acquisitional issues influence query optimization, dissemination, and execution. We evaluate these issues in the context of TinyDB, a distributed query processor for smart sensor devices, and show how acquisitional techniques can provide significant reductions in power consumption on our sensor devices.
14211318
An architecture for fast processing of large unstructured data sets
This paper presents a general system architecture tailored to perform searching, filtering, compression, encryption, and other operations on unstructured data streaming from a disk system. The system achieves high performance on such applications by providing for parallelism, hardware-application specialization and reconfiguration, and hardware placement near the disk systems. A limited prototype of a single compute node has been implemented and is described. The prototype is tailored to applications involving complex searching and its performance is compared to a pure software implementation having the same search capabilities. Performance is considered in terms of data set size, query string hit rate and query complexity. Performance results as a function of these parameters are presented and the results indicate that, for data set sizes above 1.4 MB, the prototype compute node is between one and two orders of magnitude faster than a pure software implementation. At high data set sizes, on an individual node, speedups of about 200 and a sustained throughput of 300 MB/sec have been achieved.
20626063
One-dimensional optimization on multiprocessor systems
This paper presents a straightforward approach to determining how best to utilize an MIMD multiprocessor in the solution of one-dimensional optimization problems involving continuous unimodal functions and nongradient search techniques. A methodology is presented which allows one to consider a variety of speedup functions which may occur in parallel function and systems evaluation. It is shown how the best of two parallel optimization strategies can be determined for a given accuracy, number of processors, and speedup function.
52807784
Clocked and asynchronous instruction pipelines
Clocked (synchronous) and self-timed (asynchronous) represent the two prinicipal methodologies associated with timing control and synchronization of digital systems. In this paper, clocked and the asynchronous instruction pipelines are modeled and compared. The approach which yields the best performance is dependent on technology parameters, operating range and pipeline algorithm characteristics. Design curves are presented which permit selection of the best approach for a given application and technology environment.
40669893
Identity-Based Encryption from the Weil Pairing
We propose a fully functional identity-based encryption scheme (IBE). The scheme has chosen ciphertext security in the random oracle model assuming an elliptic curve variant of the computational Diffie-Hellman problem. Our system is based on the Weil pairing. We give precise definitions for secure identity based encryption schemes and give several applications for such systems.
42557345
Performance effects of synchronization in parallel processors
We investigate synchronization activities in application executing on distributed-memory MIMD architectures. Three applications are used to quantify the performance impact of synchronization as the number of processors is increased. We also investigate the performance improvement possible when synchronization is supported in hardware. The results show that significant performance improvement can be achieved. The hardware support should include barrier synchronization, operate-and-broadcast, and operations over subsets of processors.<<ETX>>