In this paper, we present a mixed MIMD / SIMD execution model for a reconfigurable computer. This model is adapted to the use of a specialized associative coprocessor, embedded in this host machine. A main characteris...
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ISBN:
(纸本)0818620528
In this paper, we present a mixed MIMD / SIMD execution model for a reconfigurable computer. This model is adapted to the use of a specialized associative coprocessor, embedded in this host machine. A main characteristic of the model is that it uses four types of processes (decoding, calculus, coprocessor communication and transaction manager), and that in principle one process of each type is allowed on each processor. Time intervals are allocated to operations into partitions of the set of processors. Transfers are usually limited to identifiers, logical addresses and locks. Simulations display a high level of processors occupation. Therefore the machine yield may be very high, and the operations should be very fast.
Recovering from node failures is a critical issue in distributed database systems. In conventional log-based recovery protocols, the nodes providing recovery service may be overburdened, especially when the recovery i...
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ISBN:
(纸本)0769520693
Recovering from node failures is a critical issue in distributed database systems. In conventional log-based recovery protocols, the nodes providing recovery service may be overburdened, especially when the recovery is resource consuming. In this paper, an agent-based dynamic recovery protocol is presented. It divides the whole recovery process into three major steps: log-recovery, agent-recovery, and synchronization. The key idea of this protocol is to cache new database operations initiated during recovery into agents. All these cached operations are then replayed independently for further recovery. The analysis indicates that the new protocol can minimize internode's dependency and improve recovery speed. As a result, system failure rate is cut down and the overall performance gets improved.
This article describes the keynote speech on INODE presented at Fourth international Workshop on systems and Network Telemetry and Analytics (SNTA) which is collocated with international ACM symposium on High -Perform...
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ISBN:
(纸本)9781450383868
This article describes the keynote speech on INODE presented at Fourth international Workshop on systems and Network Telemetry and Analytics (SNTA) which is collocated with international ACM symposium on High -Performance parallel and distributed Computing (HPDC) on June 21 in Stockholm, Sweden.
The author describes the state of the art in models of concurrency. The models are analyzed along two dimensions: communication and computation. Some problems which make it difficult to realize large-scale concurrent ...
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ISBN:
(纸本)0818608935
The author describes the state of the art in models of concurrency. The models are analyzed along two dimensions: communication and computation. Some problems which make it difficult to realize large-scale concurrent systems are examined. Such problems include compositionality, heterogeneity, debugging, resource management, and concurrency control. Some useful comparisons are drawn to problems in distributeddatabases, and it is argued that solutions to these problems cross disciplinary boundaries. Finally, the author discusses trends in building concurrent computers and provides some expectations for the future.
In this paper we introduce and discuss a model of distributed data processing. For this purpose, a typical application system is analyzed and divided into sub-applications. To fulfill the task of the global applicatio...
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ISBN:
(纸本)0818620528
In this paper we introduce and discuss a model of distributed data processing. For this purpose, a typical application system is analyzed and divided into sub-applications. To fulfill the task of the global application, the sub-applications have to communicate in an appropriate manner by exchanging data resp. information. In our model the communication between sub-applications is split up into two steps: the offering of information by sending sub-applications, and its acceptance by receiving sub-applications. For both communication steps synchronous and asynchronous processing modes are defined. Supporting those different communication modes the cooperation between sub-applications can be defined very closely to the specific demands of the application system. This optimizes distributed data processing. At last we demonstrate the prototype implementation of a distributed data management system, which is based on the flexible communication mechanism described in the paper.
Highly parallel scalable multiprocessing systems (HMPs) are powerful tools for solving large-scale scientific and engineering problems. However, these machines are difficult to program since algorithms must exploit lo...
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Highly parallel scalable multiprocessing systems (HMPs) are powerful tools for solving large-scale scientific and engineering problems. However, these machines are difficult to program since algorithms must exploit locality in order to achieve high performance. Vienna Fortran was the first fully specified data-parallel language for HMPs that provided features for the specification of data distribution and alignment at a high level of abstraction. In this paper we outline the major elements of Vienna Fortran and compare it to High Performance Fortran (HPF), a de-facto standard in this area. A significant weakness of HPF is its lack of support for many advanced applications, which require irregular data distributions and dynamic load balancing. We introduce HPF+, an extension of HPF based on Vienna Fortran, that provides the required functionality.
Workflow Management systems automate the execution of business processes allowing the concurrent execution of multiple process instances. Existing systems do not provide a mechanism to guarantee correct concurrent exe...
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ISBN:
(纸本)0818676833
Workflow Management systems automate the execution of business processes allowing the concurrent execution of multiple process instances. Existing systems do not provide a mechanism to guarantee correct concurrent execution and, as a result, it is not possible to coordinate and synchronize different process instances. Part;of the problem is that conventional techniques are not entirely suitable for workflow environments. In databases, locks are the basic mechanism. In operating systems, this is achieved using semaphores or monitors. Neither of these approaches is appropriate for workflow applications. In this paper a method is proposed to enforce correct interleavings and guarantee mutual exclusion, as defined by the user, between concurrent workflow processes. The proposed protocol takes advantage of the semantic constructs associated with workflow management to solve some complex problems like dealing with inherited restrictions and the coarse granularity of workflow specifications.
We introduce the all-software, standard C++-based Aurora distributed shared data system. As with related systems, it provides a shared data abstraction on distributed memory hardware. An innovation in Aurora is the us...
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ISBN:
(纸本)0818677937
We introduce the all-software, standard C++-based Aurora distributed shared data system. As with related systems, it provides a shared data abstraction on distributed memory hardware. An innovation in Aurora is the use of scoped behaviour for per-context data sharing optimizations (i.e., portion of source code, such as a loop or phase). With scoped behaviour a new language scope (e.g., nested braces) can be used to optimize the data sharing behaviour of the selected source code. Different scopes and different shared data can be optimized in different ways. Thus, scoped behaviour provides a novel level of flexibility to incrementally tune the parallel performance of an application.
Semijoin has traditionally been relied upon for reducing the communication cost required for distributed query processing. However, judiciously applying join operations as reducers can lead to further reduction in the...
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ISBN:
(纸本)0818620528
Semijoin has traditionally been relied upon for reducing the communication cost required for distributed query processing. However, judiciously applying join operations as reducers can lead to further reduction in the communication cost. In view of this fact, we explore in this paper the approach of using join operations, in addition to semijoins, as reducers in distributed query processing. We first show that the problem of determining a sequence of join operations for a query graph can be transformed to that of finding a set of cuts to that graph, where a cut to a graph is a partition of the nodes in that graph. In light of the mapping we develop an efficient heuristic algorithm to determine an effective sequence of join reducers for a query. The algorithm using the concept of divide-and-conquer is shown to have polynomial time complexity. Examples are also given to illustrate our results.
Performance fluctuations are common in various software such as databases and software networking stacks. A fluctuation refers different performance (latency, throughput) for similar or identical data-items (e.g. requ...
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ISBN:
(纸本)9781538655559
Performance fluctuations are common in various software such as databases and software networking stacks. A fluctuation refers different performance (latency, throughput) for similar or identical data-items (e.g. requests, queries, packets) due to non-functional states such as cache warmth. While tail latency caused by fluctuations badly affect user experiences, diagnosing them is difficult as reproducing non-functional states in a controlled environment is not feasible. To this end, we estimate elapsed time of each function for each data-item individually to observe a single fluctuation occurrence online so that reproducing non-functional states is no longer needed. The issue is that instrumentation-based tracing methods are too heavy because a function takes a few micro seconds in high-throughput software systems for the multi-core age. We propose a hybrid approach of instrumentation and hardware-based sampling. It enables to diagnose performance fluctuations of high-throughput software systems with acceptable and adjustable overhead. Our evaluations show that it can clearly show a performance fluctuation that occurs by different cache-warmth in a sample application, and that it can be also applied to realistic software.
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