Paper Accepted at an Outstanding International Conference in CS under the BK21 Plus Programme — The 36th ACM/SIGAPP Symposium on Applied Computing, Operating Systems Track
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Paper Accepted at the ACM/SIGAPP Symposium on Applied Computing (First author: Lee Chang-gyu; corresponding author: Professor Kim Young-jae)
△ From left: Lee Chang-gyu (combined master's–doctoral, 7th semester; supervisor: Professor Kim Young-jae), Kang Hyun-gu (combined master's–doctoral, 4th semester; supervisor: Professor Kim Young-jae), Hwang Soon (master's, 2nd semester; supervisor: Professor Kim Young-jae), Professor Kim Young-jae (corresponding author)
A paper titled 'Concurrent File Metadata Structure Using Readers-Writer Lock', written by graduate student Lee Chang-gyu (combined master's–doctoral, 7th semester) of the Department of Computer Science & Engineering under the supervision of Professor Kim Young-jae, has been accepted for publication at the ACM/SIGAPP Symposium on Applied Computing (ACM/SIGAPP SAC), listed at an adjusted IF of 1 among the outstanding international conferences in computer science under the BK21 Plus programme. The paper will appear in the ACM/SIGAPP SAC Operating Systems Track.
The research presents a solution to the performance bottleneck that arises in shared-file parallel I/O, an approach widely used to accelerate data input and output in scientific applications such as databases and particle simulations. It also analyses cases of failure to guarantee data consistency that appear under the simple concurrent-access schemes commonly used, and presents nCache, a file metadata framework that resolves these while retaining high concurrency and parallelism.
Figure 1. A case of failure to guarantee data consistency during shared-file access in an existing file system
Figure 2. nCache's consistency guarantee method using double-checked locking
Figure 1 is an example of the failure to guarantee data consistency that occurs when an existing file system permits only concurrent access to a shared file. Despite the use of a readers-writer (RW) lock for synchronization, some data written concurrently becomes isolated and inaccessible. The nCache proposed in this paper, however, uses double-checked locking as shown in Figure 2, so that concurrently written data is not isolated and all of it remains accessible.
Figure 3. Performance comparison on a 120-core server Figure 4. Performance comparison for scientific applications
As Figures 3 and 4 show, the proposed nCache structure effectively improved the performance bottleneck on a manycore server with 120 cores. The same effect was observed across devices of varying capability, from consumer PC SSDs to server SSDs, and databases and scientific applications also showed substantial performance gains.
The research forms part of ETRI's (Electronics and Telecommunications Research Institute) 'Foundational Research on High-Performance Manycore-Based Operating Systems' project, which researches next-generation high-performance operating systems for the manycore systems that have emerged as CPU core counts rise within a single server. Research teams from Georgia Tech (USA), Virginia Tech (USA), Seoul National University, Yonsei University and Sungkyunkwan University are taking part; at Sogang University, the research teams of Professor Park Sung-yong and Professor Kim Young-jae of the Department of Computer Science & Engineering are participating. Research is currently being carried out in a manycore environment with 120 CPU cores, and research on OS and file system scalability as core counts rise is planned in a 192-core manycore environment.
ACM/SIGAPP SAC is a distinguished international conference for the latest research in applied computing. Its Operating Systems Track centres on research into high-performance operating systems in response to changing computer applications and hardware architectures. Owing to COVID-19 the conference will be held online this year, from 22 to 26 March.
ACM/SIGAPP SAC 2021 conference site: https://www.sigapp.org/sac/sac2021/
'Concurrent File Metadata Structure Using Readers-Writer Lock' paper: https://lass.sogang.ac.kr/pdf/2021/intl_conf/SAC_2021_CGLee.pdf