waashk/acm huggingface dataset:
a comparison of architectural support for messaging in the tmc cm-5 and the cray t3d programming models based on messaging continue to be an important programming model for parallel machines. messaging costs are strongly influenced by a machine's network interface architecture. we examine the impact of architectural support for messaging in two machines --- the tmc cm-5 and the cray t3d --- by exploring the design and performance of several messaging implementations. the additional features in the t3d support remote operations: memory access, fetch-and-increment, atomic swaps, and prefetch.experiments on the cm-5 show that requiring processor involvement for message reception can increase the communication overheads from 60% to 300% for moderate variations in computation grain size at the destination. in contrast, the t3d hardware for remote operations decouples message reception from processor activity, producing high-performance messaging independent of computation grain size or variability.in addition, hardware support for a shared address space in the t3d can be used to solve the output contention problem (output hot spots), producing messaging implementations that are robust over a wide variety of traffic patterns. atomic swap hardware can be used to build a distributed message queue, enabling a "pull" messaging scheme where the destination requests data transfer upon receive. this scheme uses prefetches to mask receive latency. while this yields performance robust over output contention, its base cost is competitive only for small messages (up to 64 bytes) because of the high cost of issuing and resolving prefetches in the t3d. emulation shows that if the interaction costs can be reduced by a factor of eight (250ns to 31ns), perhaps by moving the prefetch queue on chip, and there is a corresponding increase in the prefetch queue size, the pull scheme can give superior performance in all eases. vijay karamcheti andrew a. chien
highly personalized information delivery to mobile clients  the inherent limitations of mobile devices necessitate information to be delivered to mobile clients to be highly personalized according to their profiles. this information may be coming from a variety of resources like web servers, company intranets, email servers. a critical issue for such systems is scalability, that is, the performance of the system should be in acceptable limits when the number of users increases dramatically. another important issue is being able to express highly personalized information in the user profiles which requires a querying power as that of sql on relational databases. finally, the results should be customized according to user needs and preferences. since the queries will be executed on the documents fetched over the internet, it is natural to expect the documents to be xml documents.  this paper describes an architecture for mobile network operators to deliver highly personalized information from xml resources to mobile clients. to achieve high scalability in this architecture, we index the user profiles rather than the documents because of the excessively large number of profiles expected in the system. in this way all queries that apply to a document at a given time are executed in parallel through a finite state machine (fsm) approach while parsing the document. furthermore the queries that have the same fsm representation are grouped and only one finite state machine is created for each group which contributes to the excellent performance of the system as demonstrated in the performance evaluation section.  to provide for user friendliness and expressive power, we have developed a graphical user interface that translates the user profiles into xml-ql. xml- ql's querying power and its elaborate construct statement allow the format of the results to be specified. the results to be pushed to the mobile clients are converted to wireless markup language (wml) by the delivery component of the system.  bahattin ozen ozgur kilic mehmet altinel asuman dogac
reliable and efficient hop-by-hop flow control  hop-by-hop flow control can be used to fairly share the bandwidth of a network among competing flows. no data is lost even in overload conditions; yet each flow gets access to the maximum throughput when the network is lightly loaded. however, some schemes for hop-by-hop flow control require too much memory; some of them are not resilient to errors. we propose a scheme for making hop- by-hop flow control resilient and show that it has advantages over schemes proposed by kung. we also describe a novel method for sharing the available buffers among the flows on a link; our scheme allows us to potentially reduce the memory requirement (or increase the number of flows that can be supported) by an order of magnitude. most of the work is described in the context of an atm network that uses credit based flow control. however our ideas extend to networks in which flows can be distinguished, and to rate based flow control schemes.  cuneyt ozveren robert simcoe george varghese
the big three - today's 16-bit microprocessor  this paper reports on the functional evaluation of the three 16-bit microprocessors, namely the intel 8086, the zilog z8000, and the motorola mc68000. these microprocessors were employed in several crt applications, both monochrome and color. execution time benchmark tests were made, mechanization problems compared and instruction/architectural characteristics highlighted. conclusions and recommendations are made applicable to terminals and similar sperry univac products.  r. k. bell w. d. bell t. c. cooper t. k. mcfarland
using space-time grid for efficient management of moving objects  efficient storage and retrieval of moving objects in dbms have received significant interest recently. there are applications that would benefit from the management of dynamically changing information about moving objects. in this paper, we develop a system that manages such information interacting with moving objects. we model the space-time domain space as a grid (space-time grid) and model the trajectory of a moving object as a polyline in the space- time grid. the polyline is the result of the interactions among other moving objects. in this paper, the insertion algorithm and several other query processing algorithms are presented.  hae don chon divyakant agrawal amr el abbadi
synchronizing processors through memory requests in a tightly coupled multiprocessor  to satisfy the growing need for computing power, a high degree of parallelism will be necessary in future supercomputers. up to the late 70s, supercomputers were either multiprocessors (simd-mimd) or pipelined monoprocessors. current commercial products combine these two levels of parallelism.  effective performance will depend on the spectrum of algorithms which is actually run in parallel. in a previous paper [je86], we have presented the dspa processor, a pipeline processor which is actually performant on a very large family of loops.  in this paper, we present the greedy network, a new interconnection network (in) for tightly coupled multiprocessors (tcms). then we propose an original and cost effective hardware synchronization mechanism. when dspa processors are connected with a shared memory through a greedy network and synchronized by our synchronization mechanism, a very high parallelism may be achieved at execution time on a very large spectrum of loops including loops where independency of the successive iterations cannot be checked at compile time as e.g. loop 1:  do 1 i=1 n  1 a(p(i)=a(q(i))  a. seznec y. jegou
problems and approaches for a teraflop processor  this paper discusses problems associated with designing a processor capable of sustaining a teraflop (1012 floating point operations per second) of processing power. several researcher have speculated on achieving this performance. the technical problems of a practical design are shown to be formidable. however, none of these problems requires a technology breakthrough for their solution. the predictable advances of the next generation of technology together with a major engineering effort is all that will be required to build such a parallel machine with usable teraflop processing power.  a. h. frey g. c. fox
the horizon supercomputing system: architecture and software  horizon is the name currently being used to refer to a shared-memory multiple instruction stream - multiple data stream (mimd) computer architecture under study by independent groups at the supercomputing research center and at tera computer company. its performance target is a sustained rate of 100 giga (1011) floating point operations per second (flops). horizon achieves this speed with a few hundred identical scalar processors. each processor has a horizontal instruction set that allows the production of one or more floating point results per cycle without resorting to vector operations. memory latency is hidden, assuming enough parallelism is available, by allowing processors to switch context on each machine cycle.  in this overview, the horizon architecture is introduced and its performance is estimated. the processor instruction set and a simple programming example are given. additional details on the processor architecture, interconnection network design, performance analyses, machine simulator, compiler development, and application studies can be found in companion papers.  j. t. kuehn b. j. smith
performance analysis of redundant-path networks for multiprocessor systems  performance of a class of multistage interconnection networks employing redundant paths is investigated. redundant path networks provide significant tolerance to faults at minimal costs; in this paper improvements in performance and very graceful degradation are also shown to result from the availability of redundant paths. a markov model is introduced for the operation of these networks in the circuit-switched mode and is solved numerically to obtain the performance measures of interest. the structure of the networks that provide maximal performance is also characterized.  krishnan padmanabhan duncan h. lawrie
the eifel retransmission timer  we analyze two alternative retransmission timers for the transmission control protocol (tcp). we first study the retransmission timer of tcp-lite which is considered to be the current de facto standard for tcp implementations. after revealing four major problems of tcp-lite's retransmission timer, we propose a new timer, named the eifel retransmission timer, that eliminates these. the strength of our work lies in its hybrid analysis methodology. we develop models of both retransmission timers for the class of network-limited tcp bulk data transfers in steady state. using those models, we predict the problems of tcp-lite's retransmission timer and develop the eifel retransmission timer. we then validate our model-based analysis through measurements in a real network that yield the same results.  r. ludwig k. sklower
network support for ip traceback  this paper describes a technique for tracing anonymous packet flooding attacks in the internet back toward their source. this work is motivated by the increased frequency and sophistication of denial-of-service attacks and by the difficulty in tracing packets with incorrect, or "spoofed," source addresses. in this paper, we describe a general purpose traceback mechanism based on probabilistic packet marking in the network. our approach allows a victim to identify the network path(s) traversed by attack traffic without requiring interactive operational support from internet service providers (isps). moreover, this traceback can be performed "post mortem"\---after an attack has completed. we present an implementation of this technology that is incrementally deployable, (mostly) backward compatible, and can be efficiently implemented using conventional technology.  stefan savage david wetherall anna karlin tom anderson
implementation trade-offs in using a restricted data flow architecture in a high performance risc microprocessor the implementation of a superscalar, speculative execution sparc-v9 microprocessor incorporating restricted data flow principles required many design trade-offs. consideration was given to both performance and cost. performance is largely a function of cycle time and instructions executed per cycle while cost is primarily a function of die area. here we describe our restricted data flow implementation and the means with which we arrived at its configuration. future semiconductor technology advances will allow these trade-offs to be relaxed and higher performance restricted data flow machines to be built. m. simone a. essen a. ike a. krishnamoorthy t. maruyama n. patkar m. ramaswami m. shebanow v. thirumalaiswamy d. tovey
performance of multipath routing for on-demand protocols in mobile ad hoc networks  mobile ad hoc networks are characterized by multi-hop wireless links, absence of any cellular infrastructure, and frequent host mobility. design of efficient routing protocols in such networks is a challenging issue. as class of routing protocols called on- demandprotocols hs recently found attention because of their low routing overhead. the on-demand protocols depend on query floods to discover routes whenever a new route is needed. such floods take up a substantial portion of network bandwidth. we focus on a particular on-demand protocol, called dynamic source routing, and show how intelligent use of multipath techniques can reduce the frequency of query floods. we develop an analytic modeling framework to determine the relative frequency of query floods for various techniques. our modeling effort shows that while multipath routing is significantly better than single path routing, the performance advantage is small beyond a few paths and for long paths lengths. it also shows that providing all intermediate nodes in the primary (shortest) route with alternative paths has a significantly better performance than providing only the source with alternate paths. we perform some simulation experiments which validate these findings.  asis nasipuri robert castañeda samir r. das
distributed round-robin and first-come first-serve protocols and their applications to multiprocessor bus arbitration  two new distributed protocols for fair and efficient bus arbitration are presented. the protocols implement round-robin (rr) and first-come first-serve (fcfs) scheduling, respectively. both protocols use relatively few control lines on the bus, and their logic is simple. the round-robin protocol, which uses statically assigned arbitration numbers to resolve conflict during an arbitration, is more robust and simpler to implement than previous distributed rr protocols that are based on rotating agent priorities. the proposed fcfs protocol uses partly static arbitration numbers, and is the first practical proposal for a fcfs arbiter known to the authors. the proposed protocols thus have a better combination of efficiency, cost, and fairness characteristics than existing multiprocessor bus arbitration algorithms.  three implementations of our rr protocol, and two implementations of our fcfs protocol, are discussed. simulation results are presented that address: 1) the practical potential for unfairness in the simpler implementation of the fcfs protocol, 2) the practical implications of the higher waiting time variance in the rr protocol, and 3) the allocation of bus bandwidth among agents with unequal request rates in each protocol. the simulation results indicate that there is very little practical difference in the performance of the two protocols.  m. k. vernon u. manber
dynamic capacity allocation and hybrid multiplexing techniques for atm wireless lans  we consider digital wireless multimedia lans and time- varying traffic rates. to deal effectively with the dynamics of the time- varying traffic rates, a traffic monitoring algorithm (tma) is deployed to dynamically allocate channel capacities to the heterogeneous traffics. the tma is implemented as a higher level protocol that dictates the capacity boundaries within two distinct framed transmission techniques: a framed time domain-based (ftdb) technique and a framed cdma (fcdma) technique. the performance of the tma in the presence of the ftdb technique is compared to its performance in the presence of the fcdma technique for some traffic scenarios. the performance metrics used for the tma-ftdb and tma-fcdma combinations are channel capacity utilization factors, traffic rejection rates, and traffic delays. it is found that the tma-ftdb is superior to the tma-fcdma when the speed of the transmission links is relatively low and the lengths of the transmitted messages are relatively short. as the speed of the transmission links and the length of the transmitted messages increase, the tma-fcdma eventually outperforms the tma-ftdb.  anthony burrell harold p. stern p. papantoni-kazakos
a comparison of channel scanning schemes for distributed formation and reconfiguration  a packet radio network (for example, wireless lan, mobile tactical network) consists of a number of nodes, each equipped with a transceiver, exchanging data packets via radio channels. in this paper we identify and discuss issues related to the process of forming a network in an automatic and distributed manner. during network initialisation and reconfiguration, the time to complete the network formation process is an important performance parameter. we define two measures which can be used for computing the network formation time. also, we present a comparative evaluation of two channel-scanning schemes (synchronous and asynchronous) for multiple frequency operations using a broadcast access scheme based on csma. our study of networks with different spatial distributions of nodes shows that the asynchronous scanning scheme performs better when the ratio of the number of 1-hop neighbours to the number of available channels is high. its performance is somewhat worse than that of the synchronous scheme for sparse networks. it is also sensitive to changes in the channel dwell time of the receivers, compared with the synchronous case.  a. o. mahajan a. j. dadej k. v. lever
amtree: an active approach to multicasting in mobile networks  active networks (ans) are a new paradigm in computer networking. in ans, programs can be injected into routers and switches to extend the functionalities of the network. this allows programmers to enhance existing protocols and enables the rapid deploymentof new protocols. little work has been done in the area of multicast routing in heterogeneous environments. in this paper, we propose amtree, an an-based multicast tree that is bidirectional, optimizable on demand and adaptive to source migration. we show how ans can be exploited to enable multicast tree to be modified and optimized efficiently. by filtering unnecessary signaling messages, maintaining minimal storage at routers and incorporating features from shared-tree methods we are able to achieve a scalable solution. furthermore, we introduce an an-based optimisation algorithm that is executed on demand by receivers. besides that we introduce a fast rejoin protocol for receiver migration that makes no assumptions about the existence of multicast services in foreign networks. the performance of amtree is compared to those of the bidirectional home agent (ha) method and the remote subscription method. we found that compared to the bidirectional ha method amtree has a much lower handoff and end-to-end latency. unlike the bidirectional ha method where end-to-end latency increases as the mobile host (mh) migrates further away from its ha, amtree's latency remains fairly constant. we found that after optimization, the resulting tree's end-to-end latency to be comparable to the remote subscription method but without the need for building a new multicast tree after each handoff.  kwan-wu chin mohan kumar
adaptive resource management algorithms for indoor mobile computing environments emerging indoor mobile computing environments seek to provide a user with an advanced set of communication-intensive applications, which require sustained quality of service in the presence of wireless channel error, user mobility, and scarce available resources. in this paper, we investigate two related approaches for the management of critical networking resources in indoor mobile computing environments: adaptively re-adjusting the quality of service within pre-negotiated bounds in order to accommodate network dynamics and user mobility. classifying cells based on location and handoff profiles, and designing advance resource reservation algorithms specific to individual cell characteristics.preliminary simulation results are presented in order to validate the approaches for algorithmic design. a combination of the above approaches provide the framework for resource management in an ongoing indoor mobile computing environment project at the university of illinois. songwu lu vaduvur bharghavan
high-level specification and efficient implementation of pipelined circuits  this paper describes a novel approach to high-level synthesis of complex pipelined circuits, including pipelined circuits with feedback. this approach combines a high-level, modular specification language with an efficient implementation. in our system, the designer specifies the circuit as a set of independent modules connected by conceptually unbounded queues. our synthesis algorithm automatically transforms this modular, asynchronous specification into a tightly coupled, fully synchronous implementation in synthesizable verilog.  maria-cristina marinescu martin rinard
the performance of query control schemes for the zone routing protocol in this paper, we study the performance of route query control mechanisms for the recently proposed zone routing protocol (zrp) for ad-hoc networks. the zrp proactively maintains routing information for a local neighborhood (routing zone), while reactively acquiring routes to destinations beyond the routing zone. this hybrid routing approach has the potential to be more efficient in the generation of control traffic than traditional routing schemes. however, without proper query control techniques, the zrp can actually produce more traffic than standard flooding protocols.our proposed query control schemes exploit the structure of the routing zone to provide enhanced detection (query detection (qd1/qd2)), termination (loop-back termination (lt), early termination (et)) and prevention (selective bordercasting (sbc)) of overlapping queries. we demonstrate how certain combinations of these techniques can be applied to single channel or multiple channel ad-hoc networks to improve both the delay and control traffic performance of the zrp. our query control mechanisms allow the zrp to provide routes to all accessible network nodes with only a fraction of the control traffic generated by purely proactive distance vector and purely reactive flooding schemes, and with a response time as low as 10% of a flooding route query delay. zygmunt j. haas marc r. pearlman
packet voice communicatins over pc based local area networks  this paper presents actual implementations of packet voice communication systems over two types of pc based local area networks. one is a token-passing ring network and the other is an ethernet network. the system configuration, system operation and system performance analysis is described for both networks. a formula for the maximum allowable number of active voice stations is presented for both systems.  the last part of the paper describes a proposed design for a distributed packet voice communications protocol. the protocol presented deals with the higher levels of the communication system. the purpose of the protocol is to establish and maintain a telephone conversation between two users by using the underlying network services.  eluzor friedman chaim ziegler