Instruction prefetching techniques for ultra low-power multicore architectures

As the gap between processor and memory speeds increases, memory latencies have become a critical bottleneck for computing performance. To reduce this bottleneck, designers have been working on techniques to hide these latencies. On the other hand, design of embedded processors typically targets low cost and low power consumption. Therefore, techniques which can satisfy these constraints are more desirable for embedded domains. While out-of-order execution, aggressive speculation, and complex branch prediction algorithms can help hide the memory access latency in high-performance systems, yet they can cost a heavy power budget and are not suitable for embedded systems. Prefetching is another popular method for hiding the memory access latency, and has been studied very well for high-performance processors. Similarly, for embedded processors with strict power requirements, the application of complex prefetching techniques is greatly limited, and therefore, a low power/energy solution is mostly desired in this context. In this work, we focus on instruction prefetching for ultra-low power processing architectures and aim to reduce energy overhead of this operation by proposing a combination of simple, low-cost, and energy efficient prefetching techniques. We study a wide range of applications from cryptography to computer vision and show that our proposed mechanisms can effectively improve the hit-rate of almost all of them to above 95%, achieving an average performance improvement of more than 2X. Plus, by synthesizing our designs using the state-of-the-art technologies we show that the prefetchers increase system’s power consumption less than 15% and total silicon area by less than 1%. Altogether, a total energy reduction of 1.9X is achieved, thanks to the proposed schemes, enabling a significantly higher battery life

A Hybrid Instruction Prefetching Mechanism for Ultra Low-Power Multicore Clusters

The instruction memory hierarchy plays a critical role in performance and energy efficiency of ultralow-power (ULP) processors for the Internet-of-Things (IoT) end-nodes. This is mainly due to the extremely tight power envelope and area budgets, which imply small instruction-caches (I-Cache) operating at very low supply voltages (near-threshold). The challenge is aggravated by the fact that multiple processors, fetching in parallel, require plenty of bandwidth from the I-Caches. In this letter, we propose a low-cost and energy efficient hybrid instruction-prefetching mechanism to be integrated with a ULP multicore cluster. We study its performance for a wide range of IoT applications, from cryptography to computer vision, and show that it can effectively improve the hit-rate of almost all of them to above 95% (average performance improvement of over 2 \times ). In addition, we designed our prefetcher and integrated it in a 4-cores cluster in 28 nm fully-depleted silicon-on-insulator (FDSOI) technology. We show that system's power consumption increases only by about 11% and silicon area by less than 1%. Altogether, a total energy reduction of 1.9x is achieved, thanks to more than 2x performance improvement, enabling a significantly longer battery life

Factors Affecting the Success of Mentoring Programs for Anesthesia Technology Students: A Systematic Review

Introduction: Research results have shown that there are various factors in the success of guidance programs. Ignorance of these success factors can lead to the failure of these guidance programs. The present study was conducted with the aim of determining the effective factors in the success of guidance programs for intelligence students. Methods: This article is a systematic review. To retrieve related studies, keywords related to mentor, mentoring, academic success, nurse anesthetist, etc.) with success factors in intelligence guidance programs in Scopus, PubMed, WOS, CINAHL, ERIC, Cochrane, Magiran, SID, Iranian Medical Articles Bank and Google Scholar search engine were investigated with the criteria of finding articles in Persian and English that referred to the guidance program for intelligence students in medical centers during the years 1990 to 2021. Results: After removing duplicate articles, 1077 studies were screened, and according to the prisma checklist, 13 articles were eligible for inclusion and analysis in the study. Based on the results, the mentoring relationship consists of three stages before the start, during and after the completion of the program. Observing the principles of guidance at every stage leads to the formation of success in guidance. Success factors are generally categorized into four areas: personal, motivational, educational and environmental. To point out some of the characteristics of success in mentoring, it is possible to match mentor (mentor) and mentee (disciple), determine responsibilities and goals, enthusiasm, availability, non-judgement and criticism of mentor and disciple, providing constructive feedback and having awareness of He mentioned his attitude and geographical and cultural factors. Conclusion: In order to achieve success in intelligence mentoring, it should be noted that at the very beginning, people are compatible with each other, as well as know each other's responsibilities and goals so that they can design the continuation of the mentoring program. This issue shows the higher importance of the stage before starting mentoring (the first stage) and the individual field compared to the rest of the stages and areas

Effect of type and aggregate gradation on the functional properties of porous asphalt (case study of Iran)

Abstract Porous asphalt mixtures are gaining popularity due to their ability to effectively drain surface water and mitigate traffic noise in regions with high rainfall. However, compared to conventional asphalt pavements, these types of pavements with high void content necessitate specific guidelines for achieving an optimal mix design. The performance characteristics of porous asphalt mixtures are notably influenced by the grading and composition of materials, especially with regards to their resistance to moisture damage. This study aimed to investigate the properties of porous asphalt mixtures using limestone and siliceous aggregates with varying gradations, while maintaining bitumen contents of 5% and 6%. In accordance with the regulations set forth by the National Center for Asphalt Technology, the findings indicate that siliceous-based aggregates exhibit improved void characteristics (increased by 3%) and permeability (increased by 11%). However, they also display reduced resistance to moisture-induced failures (decreased by 4%). On the other hand, adhering to the gradation recommendations provided by the National Asphalt Pavement Association guidelines, except for a slight decrease of 3% in moisture sensitivity, yields an overall enhancement of 25% in other performance characteristics. To analyze the data, statistical methods were employed, resulting in regression models with a minimum R2 value of 0.97. These models helped determine the optimal binder percentage for different aggregate types and gradations, providing valuable insights for practical implementation

Randomized Prospective Comparison of Two Protocols for Head-up Tilt Testing in Patients with Normal Heart and Recurrent Unexplained Syncope

Background: This randomized study was aimed to compare the diagnostic value of two head-up tilt testing protocols using sublingual nitroglycerin for provocation in patients with recurrent unexplained syncope and normal heart. Methods: The patients with normal findings in physical examination, electrocardiography and echocardiography were randomly submitted to one of upright tilt test protocols. The only difference between two protocols was that nitroglycerin was administered after a five minute resting phase in supine position during protocol B. We also considered eighty normal persons as the control group. Results: Out of 290 patients that underwent tilt testing, 132 patients were in group A versus 158 patients in group B. Both groups had an identical distribution of clinical characteristics. Tilt test was positive in 79 patients in group A (25 in passive phase, 54 in active phase) versus 96 patients in group B (43 in passive phase, 53 in active phase). There was no significant difference between results in two groups (P value=0.127). Forty cases were tested with protocol A and forty underwent tilt testing with protocol B. Tilt test was positive in 4 cases with protocol A versus 3 cases in protocol B. The positive rates of tilt testing with protocol A was 60% while it was 61% in protocol B. The specificity of testing with protocol A was 90% and it was 92.5% in protocol B. Conclusions: According to our data, adding a period of rest and returning to supine position before nitroglycerin administration had no additional diagnostic yield