18 research outputs found
Optimizing File Systems for High-Performance Storage Devices
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Όλ¬Έ (λ°μ¬)-- μμΈλνκ΅ λνμ : 곡과λν μ κΈ°Β·μ»΄ν¨ν°κ³΅νλΆ, 2018. 2. μΌνμ.High-performance storage technologies such as solid-state drives (SSDs) provide low-latency, high throughput, and high I/O parallelism to legacy storage systems. SSDs access data without mechanical overhead, and they often leads to order-of-magnitude improvements in performance over legacy storage devices such as hard disk drives (HDDs).
However, replacing HDDs with SSDs while keeping the software I/O stack or not exploiting SSD features does not lead to maximum performance.
In this dissertation, we optimize file systems to fully exploit the SSD features (e.g., low-latency and high I/O parallelism).
First, we analyze and explore I/O strategies in the existing file systems on low-latency SSDs.
The file systems issue and complete several I/O requests when blocks are not contiguous, which does not take advantage of the low-latency of SSDs.
To address this problem, we propose efficient I/O strategies, which transfer requests from discontiguous host memory buffers in the file systems to discontiguous storage segments in a single I/O request.
Thus, they enable file systems to fully exploit the performance of low-latency SSDs.
Second, we investigate the locking and I/O parallelism in the existing file systems on highly parallel SSDs.
In the file systems, the coarse-grained locking to access shared data structures is used and I/O operations are serialized by a single thread. For these reasons, the file systems often face the problem of lock contention and underutilization of I/O bandwidth on multi-cores with highly parallel SSDs.
To address these issues, we enable concurrent updates on data structures and parallelize I/O operations.
We implement our techniques in EXT4/JBD2 and evaluate them on low-latency and highly parallel SSDs.
The experimental results show that our optimized file system improves the performance compared to the existing EXT4 file system.Chapter 1 Introduction 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Approach and Contributions . . . . . . . . . . . . . . . . . . . . 3
1.3 Dissertation Structure . . . . . . . . . . . . . . . . . . . . . . . . 4
Chapter 2 Background 6
2.1 High-performance Storage Devices . . . . . . . . . . . . . . . . . 6
2.2 Crash Consistency in File Systems . . . . . . . . . . . . . . . . . 7
2.3 Read and Write Operations in the Existing File Systems . . . . . 9
2.4 Journal I/O in the Journaling File Systems . . . . . . . . . . . . 10
2.5 Recovery in the Journaling File Systems . . . . . . . . . . . . . . 13
2.6 Existing Locking and I/O Parallelism in Journaling File Systems 14
Chapter 3 Design and Implementation 24
3.1 Optimizing File Systems for Low-latency Storage Devices . . . . 24
3.1.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.1.2 Implementation . . . . . . . . . . . . . . . . . . . . . . . . 30
3.2 Optimizing File Systems for Highly Parallel Storage Devices . . . 33
3.2.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2.2 Implementation . . . . . . . . . . . . . . . . . . . . . . . . 39
Chapter 4 Evaluation 50
4.1 Evaluating the Optimized File System for Low-latency Storage . 50
4.1.1 Run-time Performance . . . . . . . . . . . . . . . . . . . . 52
4.1.2 Recovery Performance . . . . . . . . . . . . . . . . . . . . 57
4.1.3 Experimental Analysis . . . . . . . . . . . . . . . . . . . . 59
4.2 Evaluating the Optimized File System for Highly Parallel Storage 61
4.2.1 Run-time Performance . . . . . . . . . . . . . . . . . . . . 63
4.2.2 Recovery Performance . . . . . . . . . . . . . . . . . . . . 66
4.2.3 Experimental Analysis . . . . . . . . . . . . . . . . . . . . 67
Chapter 5 Related Work 69
5.1 Analysis and Evaluation of High-Performance storage . . . . . . 69
5.2 Study of Journaling File Systems . . . . . . . . . . . . . . . . . . 70
5.3 File and I/O System Optimizations for Low-latency Storage . . . 72
5.4 Study of Scalability in Operating Systems . . . . . . . . . . . . . 75
5.5 File and I/O System Optimizations for Highly Parallel Storage . 75
Chapter 6 Conculsion 78
6.1 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.2 Future work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79Docto
Clinical and Cytogenetic study on 3,672 Genetic Amniocentesis: YUMC 20 years experience from 1985 to 2004 years
Objective: To systematic analyze the change of the annual distribution and indications, age distribution of the patients and chromosomal results according to patientβs age and indications in midtrimester genetic amniocentesis
Methods: This study conducted between 1985 and 2004 collected 3,672 amniocenteses procedure which were done at College of Medicine, after prenatal genetic counceling for mothers who have high risk for carrying chromosomally abnormal babies.
Results: 1. The incidence of amniocentesis had been in gradual increase since the 1980ββs, however, the number has increased sharply for the patiences in mid 1990βs. 2. Of the 3,672 amniocentesis cases, 32.2% was maternal age 30 to 34 which was most common age group and followed by age 35 to 39 was 29.9% and age 25 to 29 was 27.8%. 3. The indications for amniocentesis were advanced maternal age (36.1%), abnormal maternal serum markers (31.7%) and abnormal ultrasonographic findings which implies chromosomal abnormality (9.6%). In the 1980βs, amniocentesis had earlier been used primarily for those in advanced maternal age groups, at least 35 years older. Recently maternal serum markers and ultrasonography play an important role as an indicator for the amniocentesis. 4. From the 3,672 cases, 3,556 cases showed normal diploidy and 116 cases abnormal karyotype which consisted 3.16%. In autosomal disorders, 36 Down syndrome, 15 Edward syndrome, 2 Patau syndrome were diagnosed. In Sex chromosomal anomaly, 5 Turner syndrome, 6 47XYY, and 2 Klinefelter syndrome. Add to that 31 translocation including 21 Reciprocal translocation and 10 Robertsonian translocation, and 8 deletions and 4 mosaicisms were diagnosed. Of the 354 cases with abnormal ultrasonic findings, 19 (5.4%) resulted in chromosomal anomaly. Of the 1,164 casaes with positive maternal serum markers, 42 (3.6%) resulted in chromosomal anomaly. Those who had abnormal ultrasonographic findings implying chromosomal abnormality were found to have correlation with chromosomal abnomality than other indications.
Conclusion: Midtrimester genetic amniocentesis is an important diagnostic tool in prenatal diagnosis, of which the annual incidence has been recently increased abruptly. Not only maternal age, but the maternal serum markers and ultrasonograms should be considered in prenatal counseling. Amniocentesis should be well informed to the general population.ope
An Optimal Resource Allocation Scheme for Increasing RocksDB Parallelism on High-Performance Computing Systems
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High-performance computing systems are becoming more widely used because of the increased computing power and the emergence of high-performance storage devices. The performance of applications operating on the high-performance computing systems depends on how the systemsβ available resources are allocated and applied. Facebook, a leading social network service company, uses a key-value store called RocksDB, optimized for high-performance storage devices for data storage and management. RocksDB provides a variety of configurations that allow administrators to optimally allocate available resources on their systems. In this paper, we analyzed the impact of the allocation methods of available resources of the high-performance computing systems on the performance of RocksDB. Based on this, we propose an optimal resource allocation technique that can improve the performance by increasing the parallelism of RocksDB.N
An Efficient File Distribution Scheme for Multiple Storage Devices based on I/O Characteristics of the Key-Value Store
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Όλ¬Έμμλ μμ©μμ μμ±νλ νμΌλ€μ I/O νΉμ±μ κ³ λ €νμ¬ λ€μμ μ₯μΉμ ν¨μ¨μ μΌλ‘ λΆλ¦¬ μ μ₯νλ κΈ°λ²μ μ μνλ€. μ€ν κ²°κ³Όλ₯Ό ν΅ν΄ μ½κΈ°μ μ°κΈ° μ°μ°μ λΆλ¦¬νμ¬ μ²λ¦¬ν¨μΌλ‘μ¨ μμ©μ μ±λ₯μ΄ μ΅λ 21% ν₯μλ¨μ 보μΈλ€.
Recently, many data centers have adopted high-performance storage devices to manage the ever-increasing data. In addition, multiple devices are used to efficiently process large amounts of data. However, despite the use of high-performance storage devices, performance can still be degraded when read and write operations are mixed in the workload. This is because the handling read operation is delayed until the write operations are completed. Thus, in this paper, we propose an efficient file distribution scheme based on I/O characteristics. The experimental results show that the performance of the application is improved by up to 21% by separating the read and write operations.N
A Secure P2P E-coupon Service based on Blockchain
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Electronic coupons are a digital form of paper coupons and are intended to provide discounts or rewards to customers in order to drive purchases of products and services. With the evolution of electronic commerce, electronic coupons have been employed as effective marketing methods and are widely used in many areas. However, electronic coupons have various problems in terms of security. In particular, the illegal use of electronic coupons and the problems of forgery and corruption are causing great damage to enterprises. In this paper, we propose a new service that applies blockchain to electronic coupon service to solve the problem of illegal use. Unlike the existing services, which issues and use coupons between individuals without a central trust institution, the proposed electronic coupon service solves security problems, prevents fraudulent use, and by enabling direct settlement between the shops, the stability, and efficiency of electronic coupons get enhanced.N
Framework-assisted Priority Boosting and Load Balancing for Improving Interactivity of Android Smartphones
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μ¦νμλ€.Smartphones on Android platform recently have been come into wide use. However, it is often reported that Android smartphones cannot provide enough interactivity because Android cannot distinguish interactive tasks and non-interactive tasks and they are scheduled with the same priority and preempted. Thus, it occurs poor response time. This paper proposes a framework assisted priority boosting and load balancing for improving interactivity of Android smartphones. The framework assisted priority boosting technique distinguishes the interactive task in the framework level and send the task ID to the kernel. The kernel ensures enough time to process user input by boosting the priority of distinguished task. The load balancing technique minimizes response time of boosted task by migrating tasks disturbing boosted task to other run-queue. The experiment results demonstrate the priority boosting technique reduces response time up to 22% and the load balancing technique along with priority boosting reduces response time up to 43.31% compared to the previous techniques.OAIID:oai:osos.snu.ac.kr:snu2012-01/102/0000004193/8SEQ:8PERF_CD:SNU2012-01EVAL_ITEM_CD:102USER_ID:0000004193ADJUST_YN:YEMP_ID:A005174DEPT_CD:4541CITE_RATE:0FILENAME:(CSTV12-07-09-15).pdfDEPT_NM:μ κΈ°Β·μ»΄ν¨ν°κ³΅νλΆEMAIL:[email protected]_YN:NCONFIRM:
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Authors' final versionOAIID:oai:osos.snu.ac.kr:snu2012-01/102/0000004193/9SEQ:9PERF_CD:SNU2012-01EVAL_ITEM_CD:102USER_ID:0000004193ADJUST_YN:NEMP_ID:A005174DEPT_CD:4541CITE_RATE:0FILENAME:12-06-27 μ 보과νν - Android_Interactivity.pdfDEPT_NM:μ κΈ°Β·μ»΄ν¨ν°κ³΅νλΆEMAIL:[email protected]: