A high-performance matrix-matrix multiplication methodology for CPU and GPU architectures

Current compilers cannot generate code that can compete with hand-tuned code in efficiency, even for a simple kernel like matrix–matrix multiplication (MMM). A key step in program optimization is the estimation of optimal values for parameters such as tile sizes and number of levels of tiling. The scheduling parameter values selection is a very difficult and time-consuming task, since parameter values depend on each other; this is why they are found by using searching methods and empirical techniques. To overcome this problem, the scheduling sub-problems must be optimized together, as one problem and not separately. In this paper, an MMM methodology is presented where the optimum scheduling parameters are found by decreasing the search space theoretically, while the major scheduling sub-problems are addressed together as one problem and not separately according to the hardware architecture parameters and input size; for different hardware architecture parameters and/or input sizes, a different implementation is produced. This is achieved by fully exploiting the software characteristics (e.g., data reuse) and hardware architecture parameters (e.g., data caches sizes and associativities), giving high-quality solutions and a smaller search space. This methodology refers to a wide range of CPU and GPU architectures

Dynamic Dc Ramp Shift Digital Control Technique For Improved Transient Response

A new control scheme aiming to improve the dynamic behavior of digitally controlled DC-DC converters in terms of improved settling time and overshoot is presented in this paper. The proposed approach enhances the transient response by dynamically controlling the ramp of the Digital Pulse Width Modulator (DPWM) unit by applying DC shift to the conventional ramp-based PWM during load change. This will help the compensator reach the steady-state value faster. The dynamic DC ramp shift design method presented in this paper utilizes the existing system digital controller, and does not require any additional circuitry. The presented control scheme is first analyzed, then simulated and finally experimentally verified using a DSP implementation. © 2009 IEEE

Solving the sequential ordering problem using branch and bound

The Sequential Ordering Problem (SOP) is an NP-hard problem with a wide range of applications in the domains of scheduling, logistics and compilers. The development of powerful computers and effective algorithmic techniques has made it possible to devise exact algorithms that can solve larger instances of this problem. In this paper, we present an enhanced exact algorithm for this problem using a branch-and-bound (B&B) approach. The proposed algorithm is based on a new lower-bound technique and a local-search domination technique. The new lower-bound technique uses the dynamic Hungarian algorithm to solve a Minimum-Cost Perfect Matching relaxation of the SOP. The local search domination technique prunes the sub-tree below the current node in the B&B tree if a better partial solution is found. The performance of the proposed algorithm is evaluated experimentally using three different benchmark suites: TSPLIB, SOPLIB and COMPILERS. The results of the experimental evaluation show that the proposed algorithm finds exact solutions considerably faster than previously proposed algorithms. The proposed approach significantly reduces the optimality gap to 0.217, 0.122, and 0.004 for the three respective benchmark sets, and closes five instances that were previously open

Adequacy of consent in patients with distal radius fractures

Health professionals have a legal and ethical obligation to obtain a valid consent before any procedure. The aim of this study was to assess the adequacy of consent for treatment of distal radius fractures. It also outlines potential improvements that could be made. A study of patients undergoing treatment for distal radius fracture was undertaken. We analysed the risks and complications recorded on the consent form. The common recorded risks were infection (95.6%), vascular injuries (77.8%), nerve injuries (66.7%) and stiffness (42.2%); 31.1% of the consent forms had abbreviations. Junior doctors who consented the patients performed 6.7% of the procedures. The poor documentation of risks or complications indicates that patients are not given appropriate information to ensure that the consent is valid. Proper documentation and refining of consent forms is mandatory to ensure that all major risks are understood by patients. This could go a long way in preventing litigation