Telomere: Real-Time NAND Flash Storage

Modern solid-state disks achieve high data transfer rates due to their massive internal parallelism. However, out-of-place updates for flash memory incur garbage collection costs when valid data needs to be copied during space reclamation. The root cause of this extra cost is that solid-state disks are not always able to accurately determine data lifetime and group together data that expires before the space needs to be reclaimed. Real-time systems found in autonomous vehicles, industrial control systems, and assembly-line robots store data from hundreds of sensors and often have predictable data lifetimes. These systems require guaranteed high storage bandwidth for read and write operations by mission-critical real-time tasks. In this article, we depart from the traditional block device interface to guarantee the high throughput needed to process large volumes of data. Using data lifetime information from the application layer, our proposed real-time design, called Telomere , is able to intelligently lay out data in NAND flash memory and eliminate valid page copies during garbage collection. Telomere’s real-time admission control is able to guarantee tasks their required read and write operations within their periods. Under randomly generated tasksets containing 500 tasks, Telomere achieves 30% higher throughput with a 5% storage cost compared to pre-existing techniques.

Low I/O Intensity-aware Partial GC Scheduling to Reduce Long-tail Latency in SSDs

This article proposes a low I/O intensity-aware scheduling scheme on garbage collection (GC) in SSDs for minimizing the I/O long-tail latency to ensure I/O responsiveness. The basic idea is to assemble partial GC operations by referring to several determinable factors (e.g., I/O characteristics) and dispatch them to be processed together in idle time slots of I/O processing. To this end, it first makes use of Fourier transform to explore the time slots having relative sparse I/O requests for conducting time-consuming GC operations, as the number of affected I/O requests can be limited. After that, it constructs a mathematical model to further figure out the types and quantities of partial GC operations, which are supposed to be dealt with in the explored idle time slots, by taking the factors of I/O intensity, read/write ratio, and the SSD use state into consideration. Through a series of simulation experiments based on several realistic disk traces, we illustrate that the proposed GC scheduling mechanism can noticeably reduce the long-tail latency by between 5.5% and 232.3% at the 99.99th percentile, in contrast to state-of-the-art methods.

Analisis Performa Prototype Game Pada Platform Android

Saat ini, Perkembangan teknologi sudah sangat maju. Sebagian masyarakat sudah menggunakan dan memiliki Smart Phones ataupun Mobile Phones. Salah satu aspek didalam Smart Phones adalah Game Mobile yang dapat didownload di App Store, maupun Play Store. Game Mobile memiliki kesesuaian dengan pengguna saat ini. Dalam pengembangan game mobile, salah satu yang penting adalah perfomansi yang optimum game bisa berjalan di perangkat. Penelitian merupakan penelitian awal untuk mengetahui perfomasi prototype game yang sedang dikerjakan. Analisa perfomansi mencakup komputasi rendering, scripting, phyics, animasi, garbage collection, global illumination, UI dan others. Perfomasi dilakukan dengan menggunakan tools unity profiler yang tersedia di unity 3D IDE. Hasil observasi menunjukan bahwa prototype game yang sudah dikembangkan masih mempunyai perfomansi komputasi yang buruk karena FPS yang dihasilkan hanya sampai level 15-20 FPS di mana idealnya mendapatkan 60 FPS. Diperlukan riset lanjutan untuk menentukan langkah optimasi pada prototype game sebelum melangkah ke pengembangan game yang full fitur.

Efficient Key-Value Data Placement for ZNS SSD

Log-structured merge-tree (LSM-Tree)-based key–value stores are attracting attention for their high I/O (Input/Output) performance due to their sequential write characteristics. However, excessive writes caused by compaction shorten the lifespan of the Solid-state Drive (SSD). Therefore, there are several studies aimed at reducing garbage collection overhead by using Zoned Namespace ZNS; SSD in which the host can determine data placement. However, the existing studies have limitations in terms of performance improvement because the lifetime and hotness of key–value data are not considered. Therefore, in this paper, we propose a technique to minimize the space efficiency and garbage collection overhead of SSDs by arranging them according to the characteristics of key–value data. The proposed method was implemented by modifying ZenFS of RocksDB and, according to the result of the performance evaluation, the space efficiency could be improved by up to 75%.

Solid Waste Recycling Issues in Georgia

Georgia has made many commitments by signing the Association Agreement with the European Union, including the development of an effective waste management program. Waste management policies should include issues such as: waste management, landfills, identification and classification of waste facilities, urban wastewater treatment and more. There are four types of waste: household waste; Medical waste; Biological waste and industrial waste. Each type of waste can cause great harm to the environment. The medical and industrial waste are especially dangerous. About 5-10 thousand tons of medical waste are generated in Georgia. There is less waste planning opportunities and experience at the municipal level. In small towns and rural settlements, there are not enough garbage collection containers and garbage trucks. With the economic development of the country, the amount of waste generated and collected is increasing. Like developing countries, solid waste management in Georgia is associated with challenges of national, regional and local importance, as well as financial and environmental problems. The important steps have been taken in recent years to rectify the situation: a system for the safe disposal of municipal waste in a landfill environment and health has been established in Tbilisi and the regions. There is less waste planning opportunities and experience at the municipal level. In small towns and rural settlements, there are not enough garbage collection containers and garbage trucks. With the economic development of the country, the amount of waste generated and collected is increasing. The Work has already begun on arranging new landfills. The Waste Management Code, accompanying by-laws, the National Waste Management Strategy (2016-2030) and the National Waste Management Action Plan have made it the preferred course for Georgia to become a country focused on waste prevention and recycling. Despite the positive changes, according to experts on the issue, the country still has a long way to go to achieve this goal. Several factors are particularly challenging: 1. Incentive mechanisms for waste prevention, reuse, recycling and recovery are being developed; 2. Waste processing companies should be established or strengthened; 3. Effective mechanisms for waste management costs (both for citizens and companies) to be developed; 4. An extended producer obligation should be introduced, which implies the responsibility of the producer and / or importer for the collection and treatment of specific wastes hazardous to humans and health. Key words: Solid waste, Garbage processing plants, Household waste, Medical waste, Biological waste, Industrial waste.

Characteristics and Risk Assessments of Mercury Pollution Levels at Domestic Garbage Collection Points Distributed within the Main Urban Areas of Changchun City

The mercury that is released from the centralized treatment of municipal solid waste is an important source of atmospheric mercury. We chose the main urban area of Changchun as a representative area. Environmental factors such as total mercury content, temperature, wind speed, and other factors were measured in samples from the trash cans of two types of collection points (trash cans and garbage stations), the topsoil under the selected trash cans, and the ambient air above the selected trash cans. The potential ecological risks of mercury pollution were evaluated. The results showed that the mercury content levels of all sample types in the refuse transfer station were higher than the garbage cans and there were no significant differences observed between soil surface mercury and garbage cans. The mercury content levels in the atmosphere and the surface soil at the garbage collection points were found to increase along the cascade relationship of the garbage collection. However, there were no correlations observed between the atmospheric mercury content levels and the surface soil mercury content levels with the attachments and the sum of the former two. There were no correlations observed between surface soil and the attachments, or among the attachments, surface soil, and the atmospheric mercury content levels. The mercury content levels in the attachments, surface soil, and atmosphere of the garbage collection points in the study area were negatively correlated with the loop lines. Meanwhile, the potential ecological risk indexes of the garbage cans and garbage stations were found to be high. The chronic non-carcinogenic risks of mercury to children and adults were determined to be very low. The risks of mercury to children were higher when compared with adults. The highest non-carcinogenic risks of mercury pollution were determined to be within the central area of Changchun.