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파일 단편화를 고려한 시스템 콜 순서 기반 I/O 스케줄러
박종규(Jonggyu Park),엄영익(Young Ik Eom) 한국정보과학회 2021 정보과학회 컴퓨팅의 실제 논문지 Vol.27 No.9
파일 단편화는 파일 시스템 상에 단일 파일이 다수의 불연속된 데이터 조각으로 나뉘는 것으로 해당 데이터에 접근하고자 하는 시스템 콜을 여러 개의 I/O 요청으로 분할시킨다. 현재 리눅스에서는 이렇게 분할된 I/O 요청들이 모두 완료되어야만 해당 시스템 콜을 요청한 애플리케이션에게 완료 처리 신호가 전송된다. 하지만 기존의 I/O 스케줄러에서 활용하는 LBA 기반 I/O 요청 정렬 기법은 분할된 I/O 요청들을 더욱 분산시키기 때문에 읽기 지연 시간을 증가시킨다. 이에 본 논문에서는 파일 단편화를 고려하여 각 시스템 콜에 고유한 순서를 부여하고 이를 I/O 스케줄링에 활용하는 새로운 I/O 스케줄링 기법을 제안한다. SATA SSD를 통한 실험 결과, 제안 기법은 기존 기법 대비 약 33%의 꼬리 응답 시간을 감소시킨다. File fragmentation refers to the state wherein the contents of a file lie on multiple non-contiguous data fragments. Since the current Linux kernel can allow a single I/O-related structure to convey only the data residing on a contiguous area, an I/O system call towards such fragmented data inevitably spawns multiple I/O requests. However, a system call receives a completion signal after all of the derived I/O requests are completed. In the meantime, the existing I/O schedulers adopt the Elevator scheme, which arranges the I/O requests based on LBA. Unfortunately, such re-ordering exacerbates the fragmentation overhead because it can delay the system call completion by mixing the I/O requests with other unrelated I/O requests. To address this problem, we propose a new I/O scheduling scheme that re-orders I/O requests based on the corresponding system call IDs as well as their LBAs. The experimental results demonstrate the efficacy of our scheme by achieving 33% of tail latency decline.
Jusik Park,Jihye Jeong,Jonggyu Son,Gangjun Kwon J-INSTITUTE 2021 International Journal of Martial Arts Vol.6 No.3
Jusik ParkPurpose: The purpose of this study is to provide useful information on physical fitness training to improve the performance of Taekwondo demonstration majors by identifying the characteristics of physical fitness factors ac-cording to the performance level of university Taekwondo demonstration members. Method: The subjects of this study are Taekwondo demonstration members enrolled in K University located in D city. The differences in body structure, physical fitness factors, isokinetic muscle function of the knee joint, and anaerobic exercise capacity were compared and analyzed for 3 male students in the national demonstration group and 3 male students in the general demonstration group. Results: As a result of measurement of body structure, physical fitness factors, isokinetic muscle function, and anaerobic exercise capacity of the national demonstration team and general students, there was no statistically significant difference between groups. However, through the results of this study, it was confirmed that the ratio of flexor and extensor muscles needs to be improved to an ideal ratio of 55% to 65% as suggested in previous studies to prevent damage to the lower extremities of general students. In addition, the standing long jump and sargent jump, side step, eyes closed and one leg standing, and knee joint isokinetic muscle power showed a high-er tendency in the national demonstration group compared to the general students. There was no statistically significant difference between groups in the measurement results of anaerobic exercise capacity. Conclusion: Based on the results of this study, it is thought that it will be difficult to present the characteristics of the physical fitness factors according to the performance level of Taekwondo demonstration majors. However, considering the results of many previous studies and this study, it is thought that efforts to improve agility, power, and balance ability are needed to improve the performance of Taekwondo demonstration majors. It is judged that improvement of the flexion muscle/extension muscle ratio of the lower extremities is necessary to prevent addi-tional injuries.;Jihye Jeong;Jonggyu Son;Gangjun Kwon