Program Mapping onto Network Processors by Recursive Bipartitioning and Refining
Mapping packet processing applications onto embedded network processors (NP) is a challenging task due to the unique constraints of NP systems and the characteristics of network application domains. A remarkable difference with general multiprocessor task scheduling is that NPs are often programmed into a hybrid parallel and pipeline topology. In this paper, we introduce a multilevel balancing and refining algorithm for NP program mapping. We use a divide- and-conquer approach to recursively bipartition the task graph into disjoint subdomains. At each level of bipartition, the processing resources will be co-allocated so that an estimation of throughput can be derived. The bipartition continues until the code of the tasks can be fit into the instruction memory of processing elements. Then the algorithm iteratively refines the solution by migrating tasks from the bottleneck stage to other stages. The performance of our scheme is evaluated with a suite of NP benchmarks using SUIF/Machine SUIF compiler and Intel IXA Architecture Tool. The throughput improvement is significant: average throughput is increased by 20%, and the maximum is 108%.

title: Low power network processor design using clock gating
abstract: Network processors (NPs) have emerged as successful platforms to providing both high performance and flexibility in building powerful routers. Typical NPs incorporate multiprocessing and multi-threading to achieve maximum parallel processing capabilities. We observed that under low incoming traffic rates, most processing elements (PEs) in NPs are nearly idle and yet still consume dynamic power. This paper develops a low power technique to reduce the activities of PEs according to the varying traffic volume. We propose to monitor the average number of idle threads in a time window, and gate off the clock network of unused PEs when a subset of PEs is enough to handle the network traffic. We show that our technique brings significant reduction in power consumption (up to 30%) of NPs with no packet loss and little impact to the overall throughput.

title: Asymptotics of Efficiency Loss in Competitive Market Mechanisms
abstract: We consider the loss of efficiency in competitive market mechanisms used to allocate network resources. We model large heterogeneous populations of users assuming that each user has a random utility function. We show that if the utility functions are bounded, the competitive equilibrium will be nearly as efficient as the social optimum with high probability as the number of users increases. This is the case for inelastic capacity as well as elastic capacity, under some standard assumptions. This result extends to a network setup where sources and destinations are picked at random. If, however, the utility functions are not bounded, then the loss of efficiency does not converge to zero. Collaborating simulations are also presented.

title: Fast Online Policy Gradient Learning with SMD Gain Vector Adaptation
abstract: Reinforcement learning by direct policy gradient estimation is attractive in theory but in practice leads to notoriously ill-behaved optimization problems. We improve its robustness and speed of convergence with stochastic meta-descent, a gain vector adaptation method that employs fast Hessian-vector products. In our experiments the resulting algorithms outperform previously employed online stochastic, offline conjugate, and natural policy gradient methods.

title: Evolution of a Controller with a Free Variable Using Genetic Programming
abstract: A mathematical formula containing one or more free variables is “general” in the sense that it provides a solution to an entire category of problems. For example, the familiar formula for solving a quadratic equation contains free variables representing the equation’s coefficients. Previous work has demonstrated that genetic programming can automatically synthesize the design for a controller consisting of a topological arrangement of signal processing blocks (such as integrators, differentiators, leads, lags, gains, adders, inverters, and multipliers), where each block is further specified (“tuned”) by a numerical component value, and where the evolved controller satisfies user-specified requirements. The question arises as to whether it is possible to use genetic programming to automatically create a “generalized” controller for an entire category of such controller design problems — instead of a single instance of the problem. This paper shows, for an illustrative problem, how genetic programming can be used to create the design for ‘both the topology and tuning of controller, where the controller contains a free variable.

title: Text classification without negative examples revisit
abstract: Traditionally, building a classifier requires two sets of examples: positive examples and negative examples. This paper studies the problem of building a text classifier using positive examples (P) and unlabeled examples (U). The unlabeled examples are mixed with both positive and negative examples. Since no negative example is given explicitly, the task of building a reliable text classifier becomes far more challenging. Simply treating all of the unlabeled examples as negative examples and building a classifier thereafter is undoubtedly a poor approach to tackling this problem. Generally speaking, most of the studies solved this problem by a two-step heuristic: first, extract negative examples (N) from U. Second, build a classifier based on P and N. Surprisingly, most studies did not try to extract positive examples from U. Intuitively, enlarging P by P' (positive examples extracted from U) and building a classifier thereafter should enhance the effectiveness of the classifier. Throughout our study, we find that extracting P' is very difficult. A document in U that possesses the features exhibited in P does not necessarily mean that it is a positive example, and vice versa. The very large size of and very high diversity in U also contribute to the difficulties of extracting P'. In this paper, we propose a labeling heuristic called PNLH to tackle this problem. PNLH aims at extracting high quality positive examples and negative examples from U and can be used on top of any existing classifiers. Extensive experiments based on several benchmarks are conducted. The results indicated that PNLH is highly feasible, especially in the situation where |P| is extremely small.

title: Parameter Free Bursty Events Detection in Text Streams
abstract: Text classification is a major data mining task. An advanced text classification technique is known as partially supervised text classification, which can build a text classifier using a small set of positive examples only. This leads to our curiosity whether it is possible to find a set of features that can be used to describe the positive examples. Therefore, users do not even need to specify a set of positive examples. As the first step, in this paper, we formalize it as a new problem, called hot bursty events detection, to detect bursty events from a text stream which is a sequence of chronologically ordered documents. Here, a bursty event is a set of bursty features, and is considered as a potential category to build a text classifier. It is important to know that the hot bursty events detection problem, we study in this paper, is different from TDT (topic detection and tracking) which attempts to cluster documents as events using clustering techniques. In other words, our focus is on detecting a set of bursty features for a bursty event. In this paper, we propose a new novel parameter free probabilistic approach, called feature-pivot clustering. Our main technique is to fully utilize the time information to determine a set of bursty features which may occur in different time windows. We detect bursty events based on the feature distributions. There is no need to tune or estimate any parameters. We conduct experiments using real life data, a major English newspaper Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Very Large Data Base Endowment. To copy otherwise, or to republish, requires a fee and/or special permission from the Endowment. Proceedings of the 31st VLDB Conference, Trondheim, Norway, 2005 in Hong Kong, and show that the parameter free feature-pivot clustering approach can detect the bursty events with a high success rate.