41634108
Utilizing the Metaserver Architecture in the Ninf Global Computing System
Rapid increase in speed and availability of global-network is opening up the possibilities of globally-distributed supercomputing, including our Ninf system. Ninf is designed to utilize existing numerical libraries and resources on the Web. It also has global scheduling server called the Ninf Metaserver, which is responsible for scheduling and load-distribution of parallel tasks. The metaserver keeps track of computational servers, and gathers information needed for scheduling. Using the information, it balances loads over computational servers. We performed preliminary benchmarks using the metaserver. There, we observed that scheduling cost can be ignored and dynamic scheduling by the server gained better score than static-cyclic distribution. We also report on our collaborative efforts in bridging Ninf with NetSolve, a similar system being developed at Univ. of Tennessee/ORNL.
32545241
Ninf: A Network Based Information Library for Global World-Wide Computing Infrastructure
Ninf is an ongoing global network-wide computing infrastructure project which allows users to access computational resources including hardware, software and scientific data distributed across a wide area network. Ninf is intended not only to exploit high performance in network parallel computing, but also to provide high quality numerical computation services and accesses to scientific database published by other researchers. Computational resources are shared as Ninf remote libraries executable at a remote Ninf server. Users can build an application by calling the libraries with the Ninf Remote Procedure Call, which is designed to provide a programming interface similar to conventional function calls in existing languages, and is tailored for scientific computation. In order to facilitate location transparency and network-wide parallelism, Ninf metaserver maintains global resource information regarding computational server and databases, allocating and scheduling coarse-grained computation for global load balancing. Ninf also interfaces with the WWW browsers for easy accessibility.
195869612
The EM-X parallel computer: architecture and basic performance
Latency tolerance is essential in achieving high performance on parallel computers for remote function calls and fine-grained remote memory accesses. EM-X supports interprocessor communication on an execution pipeline with small and simple packets. It can create a packet in one cycle, and receive a packet from the network in the on-chip buffer without interruption. EM-X invokes threads on packet arrival, minimizing the overhead of thread switching. It can tolerate communication latency by using efficient multi-threading and optimizing packet flow of fine grain communication. EM-X also supports the synchronization of two operands, direct remote memory read/write operations and flexible packet scheduling with priority. The paper describes distinctive features of the EM-X architecture and reports the performance of small synthetic programs and larger more realistic programs.
206034930
Performance Evaluation of a Workstation Cluster, TMC CM-5, and Intel Paragon/XP Using a Parallel Homology Analysis Program
Abstract In the homology analysis, required memory size and computing time proportionally increase with the square of the number of amino acids in protein. In order to expand the limit of size and to carry out analysis effectively, we parallelized for homology analysis program adopting the wavefront method with tiling. The performance of a workstation cluster, CM5, and Paragon was compared by using our program. For performance evaluation of these machines, we have made a model of our parallel homology analysis computation. Using the model, we can understand the characteristics of these machines with respect to our program. Execution time estimated by the execution model is in good agreement with the observation. The averaged error of the estimation to the observation on a workstation cluster, CM5, and Paragon are 0.1%, 5%, and 2%. Almost linear speed-up has been observed from 1PU to 20PUs on them. The ratio of the performance of Paragon, CM5, and the workstation cluster is 1:0.38:0.22. This ratio is constant to the variety of the size of problem and the number of processors.
31888240
Performance Improvement by Data Management Layer in a Grid RPC System
A grid RPC system provides a useful and intuitive programming interface for master-worker type applications in a grid environment. In many grid applications, such as parameter search programs, both master and workers are often required to have a large amount of common data. Since in the RPC model the data must be transferred from the master directly to each worker, the master is sometimes a bottleneck, resulting in poor performance. In order to improve the performance in such cases, we propose a model to decouple the data transfer by a data management layer from the RPC programming. We have designed and implemented a prototype data transfer layer called OmniStorage to OmniRPC, which is a grid RPC system for parallel programming in a grid environment. This allows efficient data transmission of a large amount of data by placing intermediate relay servers, taking the network topology into account, to route the communication and cache the common data in the server. We have evaluated the performance of the proposed system by using synthetic workloads and a real grid application. The results show that OmniStorage can improve the performance of OmniRPC applications compared to the case of using only OmniRPC.
12665758
Direct Execution of Linux Binary on Windows for Grid RPC Workers
Local area or campus-type networks consist of PCs using different operating systems such as Windows and Linux. These PCs are expected to have enormous potential computing power for grid computing. The majority of PCs in this type of environment run on Windows, while grid applications and middleware are often developed on Linux. The challenge is to absorb the heterogeneity of operating systems. Grid RPC is a promising programming model for the development of grid applications. We have designed and implemented an agent called BEE, which enables direct execution of Linux binary programs on Windows for a grid RPC worker. We have integrated the BEE agent into an OmniRPC system in order to make use of Windows PCs as computing resources in a hybrid grid environment combining Windows PCs into grid computing resources. The BEE agent allows Linux binaries of the program of the OmniRPC worker to be exported and run under Windows without any modification of its Linux binaries. The results of our experiments show that the performance of a worker program using BEE is almost the same as that of Windows native binary and Cygwin and is better that that of using VMware. We have demonstrated a hybrid grid environment combining Window PCs in a conventional grid of Linux nodes.
43544513
Conservativeness of Lambda over lambda-sigma-Calculus
27739305
Explicit Environments
We introduce λƐ, a simply typed calculus with environments as first class values. As well as the usual constructs of λ and application, we have e[[a]] which evaluates term a in an environment e. Our environments are a set of variable-value pairs, but environments can also be computed by function application and evaluation in some other environments. The notion of environments here is a generalization of explicit substitutions and records. We show that the calculus has desirable properties such as subject reduction, confluence, conservativity over the simply typed λβ-calculus and strong normalizability.
8686702
Theory of Judgments and Derivations
We propose a computational and logical framework NF (Natural Framework) which is suitable for presenting mathematics formally. Our framework is an extendable framework since it is open-ended both computationally and logically in the sense of Martin-Lof's theory or types. NF is developed in three steps. Firstly, we introduce a theory of expressions and schemata which is used to provide a universe for representing mathematical objects, in particular, judgments and derivations as well as other usual mathematical objects. Secondly, we develop a theory of judgments within the syntactic universe of expressions. Finally, we introduce the notions of derivation and derivation game and will show that we can develop mathematics as derivation games by regarding mathematics as an open-ended process of defining new concepts and deriving new judgments. Our theory is inspired by Martin-Lof's theory of expressions and Edinburgh LF, but conceptually much simpler. Our theory is also influenced by Gentzen's natural deduction systems.
46610662
CAL: A Computer Assisted Learning System for Computation and Logic
In this paper, we describe a computer system CAL which assists students' understanding of a lecture course in logic and computation. We introduce a new foundational theory of expressions, which is inspired by the theory of expressions due to Martin-Lof [6], and use the expressions determined by the theory to implement various syntactic objects in CAL. We also introduce the concept of derivation game, and show that various logical and computational systems given in the lecture course can be defined uniformly by derivation games.
1580777
Classical Brouwer-Heyting-Kolmogorov Interpretation
The Brouwer-Heyting-Kolmogorov interpretation explains the meaning of logical operations as operators that construct proofs from proofs of the operands. The BHK interpretation is usually understood as giving intuitionistic interpretation for the logical operators, but, as pointed out by Troelstra and van Dalen [12], it is possible to understand the BHK interpretation classically. We elaborate this idea and develop a classical theory of proofs as abstract mathematical entities where the truth of a proposition becomes equivalent to the existence of proofs of the proposition.