Technology Implications for Large Last-Level Caches

Large last-level cache (L3C) is efficient for bridging the performance and power gap between processor and memory. Several memory technologies, including SRAM, STT-RAM (MRAM), and embedded DRAM (eDRAM), have been used or considered as the technology to implement L3Cs. However, each of them has inherent weaknesses: SRAM is relatively low density and dissipates high leakage; STT-RAM has long write latency and requires high write energy; eDRAM requires refresh. As future processors are expected to have larger last-level caches, the objective of this dissertation is to study the tradeoffs associated with using each of these technologies to implement L3Cs. In order to make useful comparisons between L3Cs built with SRAM, STT-RAM, and eDRAM, we consider and implement several levels of details. First, to obtain unbiased cache performance and power properties (i.e., read/write access latency, read/write access energy, leakage power, refresh power, area), we prototype caches based on realistic memory and device models. Second, we present simplistic analytical models that enable us to quickly examine different memory technologies under various scenarios. Third, we review power-optimization techniques for each of the technologies, and propose using a low-cost dead-line prediction scheme for eDRAM-based L3Cs to eliminate unnecessary refreshes. Finally, the highlight of this dissertation is the comparison and analysis of low-leakage SRAM, low write-energy STT-RAM, and refresh-optimized eDRAM. We report system performance, last-level cache energy breakdown, and memory hierarchy energy breakdown, using an augmented full-system simulator with the execution of a range of workloads and input sets. From the insights gained through simulation results, STT-RAM has the highest potential to save energy in future L3C designs. For contemporary processors, SRAM-based L3C results in the fastest system performance, whereas eDRAM consumes the lowest energy

Refresh Matters: Energy and Performance Analysis of Large Last-Level Cache Built with Gain Cell Embedded DRAM

Embedded dynamic random access memories (eDRAMs) have high density and low leakage futures, making them suitable for implementing large last-level caches (L3Cs). However, refresh operations are required, which negatively impact the power and performance. This article investigates the impact of refresh on energy and performance of eDRAM-based L3Cs. Experiments show that refresh has minor impact on system performance but continues to be the primary source of eDRAM-based L3C energy consumption.Inte

Characterization of Natural Dye Extracted from Wormwood and Purple Cabbage for Dye-Sensitized Solar Cells

This study used natural dyes as sensitizers of dye-sensitized solar cells (DSSCs) to replace expensive chemical synthetic dyes. We prepared two natural dyes, chlorophyll dye and anthocyanin dye, by extracting them from wormwood and purple cabbage, respectively. Moreover, we mixed the prepared chlorophyll dye and anthocyanin dye at 5 different volume ratios to form cocktail dyes. For preparation of photoelectrode, P25 TiO2 nanoparticles were used to prepare paste, which was coated on fluorine-doped tin oxide (FTO) conductive glass by the spin coating method at different spin coating speeds in order to form TiO2 thin films with different thicknesses. The DSSC prepared by the cocktail dye achieves photoelectric conversion efficiency (η) of 1.95%, open-circuit voltage (VOC) of 0.765 V, and short-circuit current density (JSC) of 5.83 mA/cm2. Moreover, the prepared DSSC sensitized solely by chlorophyll extract of wormwood achieved a photoelectric conversion efficiency (η) of 0.9%, whereas the DSSC sensitized solely by anthocyanin extract of purple cabbage achieved a photoelectric conversion efficiency of 1.47%, achieving the longest lifetime of electrons amongst these three dyes

Taiwan Oscillation Network

The Taiwan Oscillation Network (TON) is a ground-based network to measure solar intensity oscillations to study the internal structure of the Sun. K-line full-disk images of 1000 pixels diameter are taken at a rate of one image per minute. Such data would provide information onp-modes withl as high as 1000. The TON will consist of six identical telescope systems at proper longitudes around the world. Three telescope systems have been installed at Teide Observatory (Tenerife), Huairou Solar Observing Station (near Beijing), and Big Bear Solar Observatory (California). The telescopes at these three sites have been taking data simultaneously since October of 1994. Anl – v diagram derived from 512 images is included to show the quality of the data

Producing Reliable Full-System Simulation Results: A Case Study of CMP with Very Large Caches

The greater detail and improved realism of full-system architecture simulation makes it a valuable computer architecture design tool. However, its unique characteristics introduce new sources of simulation variability which could make the results of such simulations less reliable. Meanwhile, the demand for more levels of cache and larger caches has increased to improve the system power and performance. This paper presents techniques to produce reliable results in full-system simulation of CMP computer systems with large caches. Specifically, we propose the detailed emulation replay warmup technique to deal with cold or incompletely warmed up large caches. We also propose the region of interest synchronization technique to prevent simulating non-representative phase when running multi-program workloads. Furthermore, we quantify the variation reduction one can achieve when using processor affinity and checkpointing. Finally, we show that by applying all four of these simulation techniques, the simulation variability is limited to less than 1% and the simulation results are therefore more reliable.Oregon Microarchitecture Lab, Intel Corporatio

Thermal Conductivity of Carbon Nanotubes and their Polymer Nanocomposites: A Review

Thermally conductive polymer composites offer new possibilities for replacing metal parts in several applications, including power electronics, electric motors and generators, heat exchangers, etc., thanks to the polymer advantages such as light weight, corrosion resistance and ease of processing. Current interest to improve the thermal conductivity of polymers is focused on the selective addition of nanofillers with high thermal conductivity. Unusually high thermal conductivity makes carbon nanotube (CNT) the best promising candidate material for thermally conductive composites. However, the thermal conductivities of polymer/CNT nanocomposites are relatively low compared with expectations from the intrinsic thermal conductivity of CNTs. The challenge primarily comes from the large interfacial thermal resistance between the CNT and the surrounding polymer matrix, which hinders the transfer of phonon dominating heat conduction in polymer and CNT. This article reviews the status of worldwide research in the thermal conductivity of CNTs and their polymer nanocomposites. The dependence of thermal conductivity of nanotubes on the atomic structure, the tube size, the morphology, the defect and the purification is reviewed. The roles of particle/polymer and particle/particle interfaces on the thermal conductivity of polymer/CNT nanocomposites are discussed in detail, as well as the relationship between the thermal conductivity and the micro- and nano-structure of the composite

Women with endometriosis have higher comorbidities: Analysis of domestic data in Taiwan

AbstractEndometriosis, defined by the presence of viable extrauterine endometrial glands and stroma, can grow or bleed cyclically, and possesses characteristics including a destructive, invasive, and metastatic nature. Since endometriosis may result in pelvic inflammation, adhesion, chronic pain, and infertility, and can progress to biologically malignant tumors, it is a long-term major health issue in women of reproductive age. In this review, we analyze the Taiwan domestic research addressing associations between endometriosis and other diseases. Concerning malignant tumors, we identified four studies on the links between endometriosis and ovarian cancer, one on breast cancer, two on endometrial cancer, one on colorectal cancer, and one on other malignancies, as well as one on associations between endometriosis and irritable bowel syndrome, one on links with migraine headache, three on links with pelvic inflammatory diseases, four on links with infertility, four on links with obesity, four on links with chronic liver disease, four on links with rheumatoid arthritis, four on links with chronic renal disease, five on links with diabetes mellitus, and five on links with cardiovascular diseases (hypertension, hyperlipidemia, etc.). The data available to date support that women with endometriosis might be at risk of some chronic illnesses and certain malignancies, although we consider the evidence for some comorbidities to be of low quality, for example, the association between colon cancer and adenomyosis/endometriosis. We still believe that the risk of comorbidity might be higher in women with endometriosis than that we supposed before. More research is needed to determine whether women with endometriosis are really at risk of these comorbidities

Association of combination antiretroviral therapy with risk of neurological diseases in patients with HIV/AIDS in Taiwan: a nested case-control study

Heterogeneous neurocognitive impairment remains an important issue, even in the era of combination antiretroviral therapy (cART), with an incidence ranging from 15% to 65%. Although ART drugs with higher penetration scores to the central nervous system (CNS) show better HIV replication control in the CNS, the association between CNS penetration effectiveness (CPE) scores and neurocognitive impairment remains inconclusive. To explore whether ART exposure is associated with the risk of neurological diseases among patients with HIV/AIDS, this study in Taiwan involved 2,571 patients with neurological diseases and 10,284 matched, randomly selected patients without neurological diseases between 2010 and 2017. A conditional logistic regression model was used in this study. The parameters for ART exposure included ART usage, timing of exposure, cumulative defined daily dose (DDD), adherence, and cumulative CPE score. Incident cases of neurological diseases, including CNS infections, cognitive disorders, vasculopathy, and peripheral neuropathy, were obtained from the National Health Insurance Research Database in Taiwan. Odds ratios (ORs) for the risk of neurological diseases were conducted using a multivariate conditional logistic regression model. Patients with a history of past exposure (OR: 1.68, 95% confidence interval [CI]:1.22–2.32), low cumulative DDDs (< 2,500) (OR: 1.28, 95% CI: 1.15–1.42), low adherence (0 < adherence (ADH) ≤ 0.8) (OR: 1.46, 95% CI: 1.30–1.64), or high cumulative CPE scores (>14) (OR: 1.34, 95% CI: 1.14–1.57) had a high risk of neurological diseases. When stratified by classes of ART drugs, patients with low cumulative DDDs or low adherence had a high risk of neurological diseases, including NRTIs, PIs, NNRTIs, INSTIs, and multi-drug tablets. Subgroup analyses also suggested that patients with low cumulative DDDs or low adherence had a high risk of neurological diseases when they had high cumulative CPE scores. Patients with high cumulative DDDs or medication adherence were protected against neurological diseases only when they had low cumulative CPE scores (≤ 14). Patients may be at risk for neurological diseases when they have low cumulative DDDs, low adherence, or usage with high cumulative CPE scores. Continuous usage and low cumulative CPE scores of ART drugs may benefit neurocognitive health in patients with HIV/AIDS

Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants

Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m2. In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, they had a much larger gain in height than they did in BMI. The unhealthiest changes—gaining too little height, too much weight for their height compared with children in other countries, or both—occurred in many countries in sub-Saharan Africa, New Zealand, and the USA for boys and girls; in Malaysia and some Pacific island nations for boys; and in Mexico for girls. Interpretation The height and BMI trajectories over age and time of school-aged children and adolescents are highly variable across countries, which indicates heterogeneous nutritional quality and lifelong health advantages and risks