Techniques to Improve Energy Efficiency on Heterogeneous Multiprocessors under Timing and Quality Constraints

Traditionally, applications are executed without the notion of a computational deadline and often use all available system resources, which leads to higher\ua0energy consumption. User specification of Quality of Service (QoS) constraints,\ua0in terms of completion time and solution quality, opens up for allocation of\ua0just enough resources to an application to finish just in time and thereby save\ua0energy. Modern heterogeneous multiprocessor (HMP) platforms provide a\ua0set of configurable resources, including a frequency range of dynamic voltage\ua0frequency scaling (DVFS), one among a set processor types, and one or a\ua0plurality of processors of each type. They can be configured at run-time to\ua0open up new opportunities for resource management.This thesis presents techniques to reduce energy consumption under QoS\ua0constraints by allocating resources at run-time on heterogeneous multiprocessor platforms targeting sequential and parallel iterative and task-parallel\ua0applications. The proposed techniques rely on a progress-tracking framework\ua0that monitors and predicts how much time is left until the application finishes.\ua0Furthermore, the proposed framework enables the prediction of computation\ua0demand and performance requirements for future iterations or tasks.\ua0The first contribution of this thesis is a resource management technique,\ua0called SLOOP, targeting single-threaded applications. SLOOP allocates resources, i.e., processor type and DVFS, for each iteration to meet deadlines\ua0while using the prediction of computational demand and execution time.The second contribution of this thesis is a resource-management scheme, called SaC, for multi-threaded applications executing on HMPs, where resources\ua0also include the number of processors besides DVFS and processor type. SaC\ua0first chooses the most energy-efficient configuration that meets the deadline.\ua0The proposed technique collects execution-time slack over subsequent iterations\ua0to select a configuration that can save energy.The third contribution of this thesis is a resource manager, called Task-RM, for task-parallel applications executing on HMPs under QoS constraints. Task-RM exploits the variance in task execution times and imbalance between\ua0sibling tasks to allocate just enough resources in terms of DVFS and processor type. It uses an innovative off-line analysis to avoid redoing scheduling analysis\ua0at run-time.Finally, the fourth contribution is a scheme, called Approx-RM, that can exploit accuracy-energy trade-offs in approximate iterative applications. Approx-RM allocates an appropriate amount of resources while guaranteeing timing\ua0and solution quality specifications. Approx-RM first predicts the iteration count required to meet the quality target and then allocates enough resources\ua0on an HMP in terms of DVFS, processor type, and processor count to save\ua0energy while meeting a performance target

Techniques to Save Energy in Heterogeneous Multicore Architectures under QoS Constraints

Typically, applications are run with available system resources leading to over-provisioning of resources which can lead to high energy consumption. If the computational demand is specified, in terms of a Quality of Service\ua0(QoS) contract, it is possible to devote just enough resources to applications\ua0and thereby reduce energy consumption. Modern heterogeneous multicore\ua0platforms, such as ARM big.LITTLE, typically provide a multidimensional\ua0space of resources, called configuration space, such as Voltage-Frequency (V-F)\ua0settings, thread count and processor types, which can be configured at run-time\ua0to open up new opportunities for resource management.\ua0This thesis presents techniques to improve energy efficiency under the constraint of QoS by managing the resource allocation at run-time for applications\ua0run on heterogeneous multicore platforms. The applications considered are iterative with a computational deadline associated with each loop iteration.\ua0The proposed techniques apply to a framework that uses applications’ outer loop iterations as a means for progress-tracking and prediction of the execution time.A first contribution of the thesis is a resource management technique for single-threaded applications that uses core type (e.g. big or little cores) and\ua0V-F settings as a configuration space to select a configuration, for each iteration,\ua0based on the execution-time prediction of future iterations and computational\ua0deadlines. The thesis shows that an energy saving of 25% over the race-to-idle\ua0state-of-the-art technique is achieved without missing any deadlines. This\ua0scheme incurs only 0.6% and 0.8% of timing and energy overheads, respectively.\ua0A second contribution of the thesis is a novel resource-management policy\ua0for multi-threaded applications. Here, the configuration space is extended to\ua0also consider the thread count, i.e., the number of cores assigned to multi-threaded applications. The proposed technique first chooses the most energy-efficient configuration that meets the computational deadline. Since an iteration\ua0typically finishes before the deadline, the proposed technique collects the\ua0generated execution-time slack over subsequent iterations with the goal of\ua0selecting a configuration that can save more energy. To allow for on-line exploration of the configuration space, at low overhead, a third contribution of\ua0the thesis is an online, low-overhead prediction method based on interpolation,\ua0that measures the execution statistics at end points of each configuration-space\ua0dimension and interpolates the values at intermediate configurations. Overall,\ua0the proposed technique saves 61% energy compared to the state-of-the-artrace-to-idle technique without missing any deadlines. Further, it only incurs\ua00.6% and 0.7% of timing and energy overheads, respectively

Understanding of Elementary School Teachers of 3rd World Country about Levels of SOLO Taxonomy

The study was entitled as “Conceptual awareness of elementary school teachers about SOLO Taxonomy in district Vehari”. The main objectives of the present study were: (1) to find out the understanding of the teachers regarding pre-structural level of SOLO taxonomy. (2) To explore conceptual awareness of teachers about the uni-structural level of SOLO taxonomy. (3) To examine the conceptual awareness of teachers about the multi-structural level of SOLO taxonomy. (4) To find out the awareness of teachers about the relational level of SOLO taxonomy. (5) To analyze the understanding of teachers about the extended abstract level of SOLO taxonomy. The population of the study comprised all the primary teachers in District Vehari. The sample included the primary teachers teaching to primary classes. As many as 272 primary teachers were selected from the Tehsil Vehari through random sampling technique. Questionnaire was constructed with a five point Likert scale and was administered to the sample. The collected data was first tabulated and then analyzed by using the frequency and percentage method. The researcher found that majority of the teachers was confused about the perception of pre-structural level. Most of the teachers have greater thoughtful perception toward first level of SOLO taxonomy, Uni-structural level. The third level of SOLO taxonomy, Multi-structural level is the level that is highly achieved and comprehensible by the primary teachers. The relational level was percept and understood by the primary teacher to a great extent. Primary teachers’ perception about the extended abstract level was reasonable. It also concluded that the problem of conceptual awareness about the levels of Structure of Observed Learning Outcomes (SOLO) taxonomy could be improved but not totally resolved. The major recommendations were that primary teachers may have a dire need of training concerning the levels of SOLO taxonomy. Teachers may educate regarding pre-structural level. DTEs may more focus on relational level of SOLO taxonomy during workshops to educate the primary teachers for better understanding. Primary teachers may be equipped with the related literature and rich material about the levels of SOLO taxonomy. DOI: 10.5901/mjss.2014.v5n23p113

Fish Scales and Their Biomimetic Applications

Biomaterials are evolving quite rapidly over the last decade. Many applications have been considered toward their involvement in saving lives in the line of duty for law enforcement agencies and military operations. This article discusses recent work on the role of biomaterials that can be considered as a competitive alternative to composites, being used against ballistic impacts. The fish-scaled biomaterials are focused on in this paper, highlighting their excellent mechanical properties and structural configurations. In its natural environment, the scale provides fishes with an armor plating, which is significantly effective in their survival against attacks of predator and the impact inflicted from sharp teeth. These bioinspired materials, if engineered properly, can provide an excellent alternative to current Kevlar® type armors, which are significantly heavier and can cause fatigue to the human body over long-term usage. The investigated materials can provide effective alternatives to heavier and expensive materials currently used in different industrial applications. Additionally, some recent development in the usage of fish scales as a biomaterial and its applications in rapid prototyping techniques are presented. Finally, this review provides useful information to researchers in developing and processing cost-effective biomaterials

Viterbi Accelerator for Embedded Processor Datapaths

We present a novel architecture for a lightweight Viterbi accelerator that can be tightly integrated inside an embedded processor. We investigate the accelerator’s impact on processor performance by using the EEMBC Viterbi benchmark and the in-house Viterbi Branch Metric kernel. Our evaluation based on the EEMBC benchmark shows that an accelerated 65-nm 2.7-ns processor datapath is 20% larger but 90% more cycle efficient than a datapath lacking the Viterbi accelerator, leading to an 87% overall energy reduction and a data throughput of 3.52 Mbit/s

Pharmacognostic, phytochemical, biological and spectroscopic analyses of Capparis decidua (Forsk.) Edgew root and stem bark

Purpose: To investigate the pharmacognostic, phytochemical, biological and spectroscopic analyses of Capparis decidua (Forsk.) Edgew root and stem bark.Methods: Plant material (root and stem bark) was collected, authenticated, shade-dried and extracted by maceration using methanol as a solvent separately. Powder microscopy was performed using a binocular microscope. Fluorescence, physico-chemical analysis and phytochemical screening for the presence of secondary metabolites were performed using standard methods. Brine shrimp lethalitybioassay was carried out using Artemia salina bioassay, while enzymatic modulatory study was performed by α-amylase inhibition assay. Microscopic analysis was carried out with scanning electron microscopy. Spectroscopic analysis was performed by Fourier transform infrared spectroscopy (FTIR).Results: Powder microscopy showed the presence of different cellular structures. Various colors were observed under ultraviolet (UV) and ordinary light when treated with different reagents. Phytochemical screening revealed the presence of alkaloids, tannins, saponins and flavonoids but phenol and cardiac glycosides were absent from both extracts. The root bark of the plant showed significant brine shrimp lethality activity.Conclusion: Capparis decidua (Forsk.) Edgew root and stem bark contain a variety of bioactive compounds that have medicinal and therapeutic potentials. Therefore, further investigations are required to elucidate their pharmacological properties. Keywords: Capparis decidua (Forsk.) Edgew, Phytochemical, Spectroscopy, α-Amylas

Effects of a high-dose 24-h infusion of tranexamic acid on death and thromboembolic events in patients with acute gastrointestinal bleeding (HALT-IT): an international randomised, double-blind, placebo-controlled trial

Background: Tranexamic acid reduces surgical bleeding and reduces death due to bleeding in patients with trauma. Meta-analyses of small trials show that tranexamic acid might decrease deaths from gastrointestinal bleeding. We aimed to assess the effects of tranexamic acid in patients with gastrointestinal bleeding. Methods: We did an international, multicentre, randomised, placebo-controlled trial in 164 hospitals in 15 countries. Patients were enrolled if the responsible clinician was uncertain whether to use tranexamic acid, were aged above the minimum age considered an adult in their country (either aged 16 years and older or aged 18 years and older), and had significant (defined as at risk of bleeding to death) upper or lower gastrointestinal bleeding. Patients were randomly assigned by selection of a numbered treatment pack from a box containing eight packs that were identical apart from the pack number. Patients received either a loading dose of 1 g tranexamic acid, which was added to 100 mL infusion bag of 0·9% sodium chloride and infused by slow intravenous injection over 10 min, followed by a maintenance dose of 3 g tranexamic acid added to 1 L of any isotonic intravenous solution and infused at 125 mg/h for 24 h, or placebo (sodium chloride 0·9%). Patients, caregivers, and those assessing outcomes were masked to allocation. The primary outcome was death due to bleeding within 5 days of randomisation; analysis excluded patients who received neither dose of the allocated treatment and those for whom outcome data on death were unavailable. This trial was registered with Current Controlled Trials, ISRCTN11225767, and ClinicalTrials.gov, NCT01658124. Findings: Between July 4, 2013, and June 21, 2019, we randomly allocated 12 009 patients to receive tranexamic acid (5994, 49·9%) or matching placebo (6015, 50·1%), of whom 11 952 (99·5%) received the first dose of the allocated treatment. Death due to bleeding within 5 days of randomisation occurred in 222 (4%) of 5956 patients in the tranexamic acid group and in 226 (4%) of 5981 patients in the placebo group (risk ratio [RR] 0·99, 95% CI 0·82–1·18). Arterial thromboembolic events (myocardial infarction or stroke) were similar in the tranexamic acid group and placebo group (42 [0·7%] of 5952 vs 46 [0·8%] of 5977; 0·92; 0·60 to 1·39). Venous thromboembolic events (deep vein thrombosis or pulmonary embolism) were higher in tranexamic acid group than in the placebo group (48 [0·8%] of 5952 vs 26 [0·4%] of 5977; RR 1·85; 95% CI 1·15 to 2·98). Interpretation: We found that tranexamic acid did not reduce death from gastrointestinal bleeding. On the basis of our results, tranexamic acid should not be used for the treatment of gastrointestinal bleeding outside the context of a randomised trial

Task-RM: A Resource Manager for Energy Reduction in Task-Parallel Applications under Quality of Service Constraints

Improving energy efficiency is an important goal of computer system design. This article focuses on a general model of task-parallel applications under quality-of-service requirements on the completion time. Our technique, called\ua0Task-RM, exploits the variance in task execution-times and imbalance between tasks to allocate just enough resources in terms of voltage-frequency and core-allocation so that the application completes before the deadline. Moreover, we provide a solution that can harness additional energy savings with the availability of additional processors. We observe that, for the proposed run-time resource manager to allocate resources, it requires specification of the soft deadlines to the tasks. This is accomplished by analyzing the energy-saving scenarios offline and by providing\ua0Task-RM\ua0with the performance requirements of the tasks. The evaluation shows an energy saving of 33% compared to race-to-idle and 22% compared to dynamic slack allocation (DSA) with an overhead of less than 1%

SLOOP: QoS-Supervised Loop Execution to Reduce Energy on Heterogeneous Architectures

Most systems allocate computational resources to each executing task without any actual knowledge of the application’s Quality-of-Service (QoS) requirements. Such best-effort policies lead to overprovisioning of the resources and increase energy loss. This work assumes applications with soft QoS requirements and exploits the inherent timing slack to minimize the allocated computational resources to reduce energy consumption. We propose a lightweight progress-tracking methodology based on the outer loops of application kernels. It builds on online history and uses it to estimate the total execution time. The prediction of the execution time and the QoS requirements are then used to schedule the application on a heterogeneous architecture with big out-of-order cores and small (LITTLE) in-order cores and select the minimum operating frequency, using DVFS, that meets the deadline. Our scheme is effective in exploiting the timing slack of each application. We show that it can reduce the energy consumption by more than 20% without missing any computational deadlines

SaC: Exploiting execution-time slack to save energy in heterogeneous multicore systems

Reducing the energy to carry out computational tasks is key to almost any computing application. We focus in this paper on iterative applications that have explicit computational deadlines per iteration. Our objective is to meet the computational deadlines while minimizing energy. We leverage the vast configuration space offered by heterogeneous multicore platforms which typically expose three dimensions for energy saving configurability: Voltage/frequency levels, thread count and core type (e.g. ARM big/LITTLE). We note that when choosing the most energy-efficient configuration that meets the computational deadline, an iteration will typically finish before the deadline and execution-time slack will build up across iterations. Our proposed slack management policy - SaC (Slack as a Currency) - proactively explores the configuration space to select configurations that can save substantial amounts of energy. To avoid the overheads of an exhaustive search of the configuration space, our proposal also comprises a low-overhead, on-line method by which one can assess each point in the configuration space by linearly interpolating between the endpoints in each configuration-space dimension. Overall, we show that our proposed slack management policy and linear-interpolation configuration assessment method can yield 62% energy savings on top of race-to-idle without missing any deadlines