Sampling and Timing: A Task for the Environmetal Process

Sampling and timing is considered a responsibility of the environment of controller software. In this paper we will illustrate a concept whereby an environmental process and multi-way events play an important role in applying timing for untimed CSP software architectures. We use this timing concept for building our control applications based on CSP concepts and with our CSP for C++ (CTC++) library. We present a concept of sampling of control applications that is orthogonal to the application. This implies global timing on the basis of timed events. We also support traditional local timing on the based of timed processes

Model-Based Proactive Read-Validation in Transaction Processing Systems

Concurrency control protocols based on read-validation schemes allow transactions which are doomed to abort to still run until a subsequent validation check reveals them as invalid. These late aborts do not favor the reduction of wasted computation and can penalize performance. To counteract this problem, we present an analytical model that predicts the abort probability of transactions handled via read-validation schemes. Our goal is to determine what are the suited points-along a transaction lifetime-to carry out a validation check. This may lead to early aborting doomed transactions, thus saving CPU time. We show how to exploit the abort probability predictions returned by the model in combination with a threshold-based scheme to trigger read-validations. We also show how this approach can definitely improve performance-leading up to 14 % better turnaround-as demonstrated by some experiments carried out with a port of the TPC-C benchmark to Software Transactional Memory

Aspect-oriented interaction in multi-organisational web-based systems

Separation of concerns has been presented as a promising tool to tackle the design of complex systems in which cross-cutting properties that do not fit into the scope of a class must be satisfied. Unfortunately, current proposals assume that objects interact by means of object-oriented method calls, which implies that they embed interactions with others into their functional code. This makes them dependent on this interaction model, and makes it difficult to reuse them in a context in which another interaction model is more suited, e.g., tuple spaces, multiparty meetings, ports, and so forth. In this paper, we show that functionality can be described separately from the interaction model used, which helps enhance reusability of functional code and coordination patterns. Our proposal is innovative in that it is the first that achieves a clear separation between functionality and interaction in an aspect-oriented manner. In order to show that it is feasible, we adapted the multiparty interaction model to the context of multiorganisational web-based systems and developed a class framework to build business objects whose performance rates comparably to handmade implementations; the development time, however, decreases significantly.Comisión Interministerial de Ciencia y Tecnología TIC2000-1106-C02-0

A Power Cap Oriented Time Warp Architecture

Controlling power usage has become a core objective in modern computing platforms. In this article we present an innovative Time Warp architecture oriented to efficiently run parallel simulations under a power cap. Our architectural organization considers power usage as a foundational design principle, as opposed to classical power-unaware Time Warp design. We provide early experimental results showing the potential of our proposal

Prompt Application-Transparent Transaction Revalidation in Software Transactional Memory

Software Transactional Memory (STM) allows encapsulating shared-data accesses within transactions, executed with atomicity and isolation guarantees. The assessment of the consistency of a running transaction is performed by the STM layer at specific points of its execution, such as when a read or write access to a shared object occurs, or upon a commit attempt. However, performance and energy efficiency issues may arise when no shared-data read/write operation occurs for a while along a thread running a transaction. In this scenario, the STM layer may not regain control for a considerable amount of time, thus not being able to early detect if such transaction has become inconsistent in the meantime. To tackle this problem we present an STM architecture that, thanks to a lightweight operating system support, is able to perform a fine-grain periodic (hence prompt) revalidation of running transactions. Our proposal targets Linux and x86 systems and has been integrated with the open source TinySTM package. Experimental results with a port of the TPC-C benchmark to STM environments show the effectiveness of our solution

A fine-grain time-sharing Time Warp system

Although Parallel Discrete Event Simulation (PDES) platforms relying on the Time Warp (optimistic) synchronization protocol already allow for exploiting parallelism, several techniques have been proposed to further favor performance. Among them we can mention optimized approaches for state restore, as well as techniques for load balancing or (dynamically) controlling the speculation degree, the latter being specifically targeted at reducing the incidence of causality errors leading to waste of computation. However, in state of the art Time Warp systems, events’ processing is not preemptable, which may prevent the possibility to promptly react to the injection of higher priority (say lower timestamp) events. Delaying the processing of these events may, in turn, give rise to higher incidence of incorrect speculation. In this article we present the design and realization of a fine-grain time-sharing Time Warp system, to be run on multi-core Linux machines, which makes systematic use of event preemption in order to dynamically reassign the CPU to higher priority events/tasks. Our proposal is based on a truly dual mode execution, application vs platform, which includes a timer-interrupt based support for bringing control back to platform mode for possible CPU reassignment according to very fine grain periods. The latter facility is offered by an ad-hoc timer-interrupt management module for Linux, which we release, together with the overall time-sharing support, within the open source ROOT-Sim platform. An experimental assessment based on the classical PHOLD benchmark and two real world models is presented, which shows how our proposal effectively leads to the reduction of the incidence of causality errors, as compared to traditional Time Warp, especially when running with higher degrees of parallelism

AnchorNet: A Weakly Supervised Network to Learn Geometry-sensitive Features For Semantic Matching

Despite significant progress of deep learning in recent years, state-of-the-art semantic matching methods still rely on legacy features such as SIFT or HoG. We argue that the strong invariance properties that are key to the success of recent deep architectures on the classification task make them unfit for dense correspondence tasks, unless a large amount of supervision is used. In this work, we propose a deep network, termed AnchorNet, that produces image representations that are well-suited for semantic matching. It relies on a set of filters whose response is geometrically consistent across different object instances, even in the presence of strong intra-class, scale, or viewpoint variations. Trained only with weak image-level labels, the final representation successfully captures information about the object structure and improves results of state-of-the-art semantic matching methods such as the deformable spatial pyramid or the proposal flow methods. We show positive results on the cross-instance matching task where different instances of the same object category are matched as well as on a new cross-category semantic matching task aligning pairs of instances each from a different object class.Comment: Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition. 201