waashk/acm huggingface dataset:
requirements for optimal execution of oops with tests  both the efficient execution of branch intensive code and knowing the bounds on same are important issues in computing in general and supercomputing in particular. in prior work, it has been suggested, implied, or left as a possible maximum, that the hardware needed to execute code with branches optimally, i.e., oracular performance, is exponentially dependent on the total number of dynamic branches to be executed, this number of branches being proportional at least to the number of iterations of the loop. for classes of code taking at least one cycle per iteration to execute, this is not the case. for loops containing one test (normally in the form of a boolean recurrence of order 1), it is shown that the hardware necessary varies from exponential to polynomial in the length of the dependency cycle l, while execution time varies from one time cycle per iteration to less than l time cycles per iteration; the variation depends on specific code dependencies.  a. uht
performance modelling of a hslan slotted ring protocol  the slotted ring protocol which is evaluated in this paper is suitable for use at very large transmission rates. in terms of modelling it is a multiple cyclic server system. a few approximative analytical models of this protocol are presented and evaluated vs the simulation in this paper. the cyclic server model shows to be the most accurate and usable over a wide range of parameters. a performance analysis based on this model is presented.  m. zafirovic- vukotic i. g. m. m. niemegeers
a methodology for designing communication protocols  we propose a compositional technique for designing protocols. the technique involves specifying constraints between the events of the component protocols. a constraint may either require synchronization between certain events of the component protocols or may require inhibiting an event in one protocol on the occurrence of an event in another component protocol. we find both types of constraints useful in composing protocols. we demonstrate the applicability of the technique by deriving several protocols. the technique facilitates modular design and verification. our technique, in conjunction with the sequential composition technique, can be used to design complex protocols.  gurdip singh
a general class of processor interconnection strategies  a new class of general topologies is proposed in this paper for interconnecting a large network of computers in parallel and distributed environment. these structures have been shown to possess small internode distances, fairly low number of links per node, easy message routing and large number of alternate paths that can be used in case of faults in the system. the interconnection is based on a mixed radix number system, presented in this paper. the technique results in a variety of structures for a given number of processors n, depending on the required diameter in the network.  a bus oriented structure is also introduced here, based on the same mathematical framework. these structures possess only two i/o ports per processor and are also shown to have small internode distances.  laxmi n. bhuyan dharma p. agrawal
vm-based shared memory on low-latency, remote-memory-access networks recent technological advances have produced network interfaces that provide users with very low-latency access to the memory of remote machines. we examine the impact of such networks on the implementation and performance of software dsm. specifically, we compare two dsm systems---cashmere and treadmarks---on a 32-processor dec alpha cluster connected by a memory channel network.both cashmere and treadmarks use virtual memory to maintain coherence on pages, and both use lazy, multi-writer release consistency. the systems differ dramatically, however, in the mechanisms used to track sharing information and to collect and merge concurrent updates to a page, with the result that cashmere communicates much more frequently, and at a much finer grain.our principal conclusion is that low-latency networks make dsm based on fine-grain communication competitive with more coarse-grain approaches, but that further hardware improvements will be needed before such systems can provide consistently superior performance. in our experiments, cashmere scales slightly better than treadmarks for applications with false sharing. at the same time, it is severely constrained by limitations of the current memory channel hardware. in general, performance is better for treadmarks. leonidas kontothanassis galen hunt robert stets nikolaos hardavellas michal cierniak srinivasan parthasarathy wagner meira sandhya dwarkadas michael scott
performance evaluation of tcp/rlp protocol stack over cdma wireless link  due to the high frame error rate in wireless communication channels, an additional link layer protocol, radio link protocol (rlp), has been introduced in the newly approved data services option standard for wideband spread spectrum digital cellular system. in this paper, we investigate performance issues of a typical cod division multiple access (cdma) wireless link using the protocol stack given in the standard. in particular, we focus on the dynamics of the tcp and rlp layers of the protocol stack since the fluctuation of systemperformance is largely caused by automatic repeat request (arq) mechanisms implemented at these two layers. we compare the network performance of default parameter setting to those of other possible parameter settings. analytical and simulation results presented in this paper can provide guidance to those attempting to further improve performance of interest.  gang bao
constructing instruction traces from cache-filtered address traces (citcat) instruction traces are useful tools for studying many aspects of computer systems, but they are difficult to gather without perturbing the systems being traced. in the past, researchers have collected instruction traces through various techniques, including single-stepping, instruction inlining, hardware monitoring, and processor simulation. these approaches, however, fail to produce accurate traces because they interfere with the processor's normal execution.because processors are deterministic machines, their behavior can be predicted if their initial states and external inputs are known. we have developed a technique, called "citcat," which exploits this fact to generate nearly perfect instruction traces through trace-driven simulation. citcat combines the best features of instruction inlining, hardware monitoring, and processor simulation to produce long, accurate instruction traces without perturbing the system being traced. because citcat instruction traces are computed, rather than stored, this hybrid technique delivers not just accurate traces, but also an extremely efficient trace compression algorithm. charlton d. rose j. kelly flanagan
the intel 8087 numeric data processor  this paper describes a new device, the intel®8087 numeric data processor, with unprecedented speed, accuracy and capability. its modified stack architecture and instruction set are explained illustrative examples are included. the 8087, which conforms to the proposed ieee floating-point standard, is a coprocessor in the intel®8086 family. it supports seven data types: three real, three integer and one packed bcd format, and performs all necessary numeric operations from addition to logarithmic and trigonometric functions.  john palmer
tornet: a local area network  tornet is an experimental local area computer network presently being designed and built in the computer group laboratory of the department of electrical engineering at the university of toronto. the network consists of a number of local rings, each attached to a central ring. the local rings employ a variation on the slotted-ring format that uses a limited insertion technique to achieve reasonable response times for character traffic among many devices and small computers. two fixed-length packet formats (one byte or 128 bytes of data) are used on the local rings. only the longer format is used on the central ring which generally provides record level access to shared specialized equipment.  the main objective in the local ring design is a low-cost port for inexpensive terminals, sensors, etc. the paper concentrates on the functional characteristics of the local rings, including delay-throughput comparisons with other well-known ring schemes.  z. g. vranesic v. c. hamacher w. m. loucks s. g. zaky
network and single user performance evaluation of a mobile data system over flat fading transmission channels  in this paper the contrasting effects of transmission impairments and capture on both the network and single user performance of a slotted aloha system are investigated in a mobile radio environment, accounting for frequency non- selective random propagation phenomena, and employing the packet error probability in order to define packet losses and capture. with this study we demonstrate that it is possible to generalize in a real propagation context a method previously proposed in literature for evaluating the network behavior in terms of steady-state throughput, backlog and stability in conventional transmission conditions, i.e., when all the transmission channels were error- free and the collisions caused the loss of all the packets involved. moreover, we indicate under which specific constraints on the terminal mobility we can apply this method to analytically predict the single user performance, which we show being an important design parameter. through the numerical results reported we quantitatively point out that in the absence of coding capture increases system stability and moderately improves the overall system throughput and backlog. we also outline the trade-off between an increased capture gain obtained by means of coding and the corresponding system cost in terms of complexity and bandwidth occupancy. furthermore, we demonstrate the unfairness which affects the single user performance and the consequent need for countermeasures in order not to discriminate among users differently located within the network; yet, this last solution is detrimental as regards the positive capture effects.  piero castoldi gianni immovilli maria luisa merani
ip multicast channels: express support for large-scale single-source applications in the ip multicast model, a set of hosts can be aggregated into a group of hosts with one address, to which any host can send. however, internet tv, distance learning, file distribution and other emerging large- scale multicast applications strain the current realization of this model, which lacks a basis for charging, lacks access control, and is difficult to scale.this paper proposes an extension to ip multicast to support the _channel_ model of multicast and describes a specific realization called _explicitly requested single-source (express)_ multicast. in this model, a multicast _channel_ has exactly one explicitly designated source, and zero or more channel _subscribers_. a single protocol supports both channel subscription and efficient collection of channel information such as subscriber count. we argue that express addresses the aforementioned problems, justifying this multicast service model in the internet. hugh w. holbrook david r. cheriton
framework for a taxonomy of fault-tolerance attributes in computer systems  a conceptual framework is presented that relates various aspects of fault- tolerance in the context of system structure and architecture. such a framework is an essential first step for the construction of a taxonomy of fault-tolerance.  a design methodology for fault-tolerant systems is used as the means to identify and classify the major aspects of fault-tolerance: system pathology, fault detection and recovery algorithms, and methods of modeling and evaluation.  a computing system is described in terms of four universes of observation and interpretation, ordered in the following sequence: physical, logic, information, and interface, or user's. the description is used to present a classification of faults, i.e., the causes of undesired behavior of computing systems.  algirdas avizienis
performance of broadcast and unknown server (bus) in atm lan emulation  in this paper, we develop performance models of the broadcast and unkn own server (bus) in the lane. the traffic on the bus is divided into two classes: the broadcast and multicast traffic, and the unicast relay flow. the broadcast and multicast traffic is assumed to form a markov modulated poisson process (mmpp). the traffic for a particular unicast relay flow is an mmpp as well. however, the number of active unicast relay flows sojourning on the bus is determined by a tandem queueing system, where the flow arrival process is poisson, the address resolution delay is exponentially distributed, and the connection setup delay is three-stage erlang distributed. the size of data frames in traffic flows is a random variable with three possible values: short, medium, and large. in order to deal with the intractability (i.e., largeness and stiffness) of the underlying markov chain, a hierarchical model is used to decompose the system. with the help of stochastic petri net package (spnp), a software package for the automated generation and solution of markovian stochastic systems, and the decomposition method, we study the performance of the bus module under different loads. we also investigate the effect of address resolution delay and connection setup delay on the performance of the bus.  hairong sun xinyu zang kishor s. trivedi
a testbed for wide area atm research  asynchronous transfer mode (atm) has been advocated as the basis of multiservice telecommunications in the next century. however, the public telecommunication technology of the 1990's will be isdn, which presents a circuit switched subscriber interface. an obvious approach to building a wide area atm network is to build it on top of primary rate isdn. in this paper we describe the lessons learned through the design and deployment of such a network.  d. l. tnnenhouse i. m. leslie
a general multi-microprocessor interconnection mechanism for non-numeric processing  mmps interconnection problems are discussed in terms of a single time-shared bus. the performance drawbacks usually associated with the single bus alternative are attributed to the high bus utilization at the basic building block level. the pended transaction bus protocol is presented as a general solution to such utilizations. such a bus is developed to support more than 50 processors without severe contention. the basic protocol of the mc68000 as a current generation microprocessor is investigated, and shown ineffective for true multi-microprocessor systems.  hoo-min d. toong svein o. strommen earl r. goodrich
a binary feedback scheme for congestion avoidance in computer networks  we propose a scheme for congestion avoidance in networks using a connectionless protocol at the network layer. the scheme uses a minimal amount of feedback from the network to the users, who adjust the amount of traffic allowed into the network. the routers in the network detect congestion and set a congestion- indication bit on packets flowing in the forward direction. the congestion indication is communicated back to the users through the transport- level acknowledgment. the scheme is distributed, adapts to the dynamic state of the network, converges to the optimal operating point, is quite simple to implement, and has low overhead. the scheme maintains fairness in service provided to multiple sources. this paper presents the scheme and the analysis that went into the choice of the various decision mechanisms. we also address the performance of the scheme under transient changes in the network and pathological overload conditions.  k. k. ramakrishnan r. jain
retrospective on high-level language computer architecture  high-level language computers (hllc) have attracted interest in the architectural and programming community during the last 15 years; proposals have been made for machines directed towards the execution of various languages such as algol,1,2 apl,3,4,5 basic,6,7 cobol,8,9 fortran,10,ll lisp,12,13 pascal,14 pl/i,15,16,17 snobol,18,19 and a host of specialized languages. though numerous designs have been proposed, only a handful of high- level language computers have actually been implemented.4,7,9,20,21 in examining the goals and successes of high-level language computers, the authors have found that most designs suffer from fundamental problems stemming from a misunderstanding of the issues involved in the design, use, and implementation of cost-effective computer systems. it is the intent of this paper to identify and discuss several issues applicable to high-level language computer architecture, to provide a more concrete definition of high-level language computers, and to suggest a direction for high-level language computer architectures of the future.  david r. ditzel david a. patterson
intersystem location update and paging schemes for multitier wireless networks  global wireless networks enable mobile users to communicate regardless of their locations. one of the most important issues is location management in a highly dynamic environment because mobile users may roam between different wireless networks, network operators, and geographical regions. in this paper, a location tracking mechanism is introduced, which consists of intersystem location updates using the concept of boundary location area (bla) and paging using the concept of boundary location register (blr). the bla is determined by a dynamic location update policy in which the velocity and the quality of service (qos) are taken into account on a per-user basis. the blr is used to maintain the records of mobile users crossing the boundary of networks. this mechanism not only reduces location tracking costs but also significantly decreases call loss rates and average paging delays. the performance evaluation of the proposed schemes is provided to demonstrate their effectiveness in multitier wireless networks.  wenye wang ian f. akyildiz
monotonic evolution: an alternative to induction variable substitution for dependence analysis  we present a new approach to dependence testing in the presence of induction variables. instead of looking for closed form expressions, our method computes _monotonic evolution_ which captures the direction in which the value of a variable changes. this information is then used in the dependence test to help determine whether array references are dependence-free. under this scheme, closed form computation and induction variable substitution can be delayed until after the dependence test and be performed on-demand. to improve computative efficiency, we also propose an optimized (non-iterative) data-flow algorithm to compute evolution. experimental results show that dependence tests based on evolution information matches the accuracy of that based on closed-form computation (implemented in polaris), and when no closed form expressions can be calculated, our method is more accurate than that of polaris.  peng wu albert cohen jay hoeflinger david padua
network locality at the scale of processes  packets on a lan can be viewed as a series of references to and from the objects they address. the amount of locality in this reference stream may be critical to the efficiency of network implementations, if the locality can be exploited through caching or scheduling mechanisms. most previous studies have treated network locality with an addressing granularity of networks or individual hosts. this paper describes some experiments tracing locality at a finer grain, looking at references to individual processes, and with fine- grained time resolution. observations of typical lans show high per-process locality; that is, packets to a host usually arrive for the process that most recently sent a packet, and often with little intervening delay.  jeffrey c. mogul
establishment communication systems: lan's or pabx's - which is better?  in the sixties and early seventies, major activities in networking were focused on private and public data networks using either circuit and packet- switching technology or integrating both switching methods into a single network. in this time frame, manufacturers of main frames defined and implemented network architectures, iso started work on the reference model of the open-system interconnect architecture, and ccitt recommended the x-series of interfaces.  local-area communication networks (lan's) represent a comparatively new field of activity which can be viewed as an extension to data networks for making high-speed packet-switching services available to the in-house domain. currently, much research and development work is being pursued in this field, both at universities and in industry. the term local refers to communication on the users' premises, i.e., within a building or among a cluster of buildings.  local data and voice communication are not new. a typical example of a system widely used today for local data communication between hosts and display terminals is a star configuration where the terminals are attached to control units tightly coupled to a processor via i/o channels. the necessary terminal control functions are provided in the control unit and shared among a set of terminals. the most widely used local communication system is the private automatic branch exchange (pabx). most pabx's installed today are optimised for real-time voice, and use analog technology.  k. kummerle
energy efficiency of tcp in a local wireless environment the focus of this paper is to analyze the energy consumption performance of various versions of tcp, namely, tahoe, reno and newreno, for bulk data transfer in an environment where channel errors are correlated. we investigate the performance of a single wireless tcp connection by modeling the correlated packet loss/error process (e.g., as induced by a multipath fading channel) as a firstorder markov chain. based on a unified analytical approach, we compute the throughput and energy performance of various versions of tcp. the main findings of this study are that (1) error correlations significantly affect the energy performance of various versions of analogous conclusions for throughput), and in particular they result in considerably better performance for tahoe and newreno than iid errors, and (2) the congestion control mechanism implemented by tcp does a good job at saving energy as well, by backing off and idling during error bursts. an interesting conclusion is that, unlike throughput, the energy efficiency metric may be very sensitive to the tcp version used and to the choice of the protocol parameters, so that large gains appear possible. michele zorzi ramesh r. rao
a grammar-based methodology for protocol specification and implementation  a new methodology for specifying and implementing communication protocols is presented. this methodology is based on a formalism called "real-time asynchronous grammars" (rtag), which uses a syntax similar to that of attribute grammars to specify allowable message sequences. in addition rtag provides mechanisms for specifying data-dependent protocol activities, real- time constraints, and concurrent activities within a protocol entity. rtag encourages a top-down approach to protocol design that can be of significant benefit in expressing and reasoning about highly complex protocols. as an example, an rtag specification is given for part of the class 4 iso transport protocol (tp-4).  because rtag allows protocols to be specified at a highly detailed level, major parts of an implementation can be automatically generated from a specification. an rtag parser can be written which, when combined with an rtag specification of a protocol and a set of interface and utility routines, constitutes an implementation of the protocol. to demonstrate the viability of rtag for implementation generation, an rtag parser has been integrated into the kernel of the 4.2 bsd unix operating system, and has been used in conjunction with the rtag tp-4 specification to obtain an rtag-based tp-4 implementation in the dod internet domain.  david p. anderson lawrence h. landweber