• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.543-544
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• 2009

본 논문은 Linux에서 사용되는 Shared Memory는 동일한 메모리 영역에 여러 개의 프로세스가 접근할 수 있도록 해 주는 기술이다. 본 논문에서는 Shared Memory의 큰 두 갈래 중 커널 단계에서 처리 되는 SVR(System V Release) 형식의 Shared Memory를 다룬다. 본 논문에서는 리눅스 운영체제의 공유 메모리 기능을 Dual Core 시스템에서 동작하도록 구현한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.770-771
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• 2009

리눅스 커널을 VMM(Virtual Machine Monitor)로 만들어 주는 KVM의 메모리 관리 기법을 분석한다. Xen과의 차이점과 KVM의 구조를 알아보고 KVM에서의 메모리 관리 기법에 대해 분석하였다. 또한 CPU의 가상화 기능인 Intel VT-x가 어떻게 적용되었는지 분석한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.197-197
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• 2022

최근 펌웨어를 겨냥한 공격이 늘어나고 있다. 기기에 수정된 펌웨어 주입이 가능하다면 장치를 무력화하거나 데이터 유출, 디도스 등의 공격이 가능하다. 본 연구는 펌웨어 보안을 위해 펌웨어 서명 및 암호화 시스템을 구축하였다. 또한 STM32MP1-DK2보드의 리눅스 커널 코드를 수정하여 이를 검증하였다.

• The KIPS Transactions:PartA
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• v.9A no.3
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• pp.327-332
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• 2002

Conventional proxy web cache, which is generally used to caching server, is a content-copy based system. This method focuses on speeding up the phase delivery not improving the webserver performance. However, if immense clients attempt to connect the webserver simultaneously, the proxy web cache cannot achieve the desired result. In this paper, we propose the web accelerator called the SCALA-AX, whitch improves web server performance by accelerating the delivery contents. The SCALA-AX is built in the Linux-based kernel as a kernel modulo and works in combination with the conventional webserver program. The SCALA-AX speeds up the processing rate of the webserver, because it processes the requests using the kernel thread. The SCALA-AX also applies the well-developed cache algorithm to the processing, and thus it obtains the advantage of the caching server without installing additional hardware. A banchmarking test demonstrates that the SCALA-AX improves webserver performance by up to 500％ for content delivery.

• Journal of KIISE
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• v.44 no.3
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• pp.232-238
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• 2017

Application response time is critical to end-user response time in Android smartphones. Due to the plentiful resources of recent smartphones, storage I/O response time becomes a major key factor in application response time. However, existing storage I/O trace tools for Android and Linux give limited information only for a specific I/O layer which makes it difficult to combine I/O information from different I/O layers, because not helpful for application developer and researchers. In this paper, we propose a novel storage I/O trace tool for Android, called AIOPro (Android I/O profiler). It traces storage I/O from application - Android platform - system call - virtual file system - native file system - page cache - block layer - SCSI layer and device driver. It then combines the storage I/O information from I/O layers by linking them with file information and physical address. Our evaluations of real smartphone usage scenarios and benchmarks show that AIOPro can track storage I/O information from all I/O layers without any data loss under 0.1% system overheads.

• Journal of KIISE
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• v.44 no.4
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• pp.363-373
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• 2017

Ext4 file system is widely used in various computing environments such as those of the PC, the server, and the Linux-based embedded system. Ext4, which uses a buffer for block I/O, provides fsync() system call to applications to guarantee the consistency of a specific file. A log of the analytical studies regarding the operation of Ext4 and the improvement of its performance has been compiled, but it has not been studied in detail in terms of kernel versions. We figure out that the behavior of fsync() system call is different depending on the kernel version. Between the kernel versions of 3.4.0 and 4.7.2, 3.4.0, 3.8.0, and 4.6.2 showed behavioral differences regarding the fsync() system call. The latency of fsync() in kernel 3.4.0 is longer than that of the more-advanced 3.7.10; meanwhile, the characteristics of 3.8.0 enabled the disruption of the Ext4 journaling order, but the ordered defect was solved with 4.6.2.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.7
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• pp.277-282
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• 2013

Recently, there is a growing need for an open software platform where developers easily write intelligent motion control applications for smart cars, smart robots, smart factories, and so on. To this end, a general-purpose operating system with rich functionalities and various hardware supports can be a candidate for such a platform, but it is known to have limitations in guaranteeing the responsiveness of individual applications. In this paper, to assess the suitability of Linux to be such a platform, we evaluate the real-time performance of Xenomai-patched Linux on an ARM-based processor Exynos4210 with motion control applications. Experimental results show that it is possible to stably provide motion cycle times below 1ms to such applications even with background workloads.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.311-318
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• 2001

In recent years, users\` demands for multimedia service are increasing because of a diffusion of internet. Server systems, however, offer inefficient multimedia data service to users. Multimedia applications often transfer the same data between shared devices at very high rates, and therefore require an efficient I/O subsystem. Data copying and context switching have long been identified as sources of I/O inefficiency. Therefore we propose the new Multimedia Stream System Call (MSSC) mechanism, which is inserted into a Linux kernel: The MSSC mechanism operates in kernel domain with RTP (Real-time Transport Protocol). We present measurements indicating that use of our techniques resulted in a 12.5%∼14% gain in throughput as compared with a conventional Linux system.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.105-112
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• 2005

As the development of information telecommunication technology and thus the information sharing and opening is accelerated, If system is exposed to various threatener and the avrious security incident is rasing its head with social problem. As countermeasure, to protect safely and prepare in the attack for a system from a be latent security threat, various security systems are been using such as IDS, Firewall, VPN etc.. But, expertise or expert is required to handle security system. The module, implemented in this paper, is based on Windows XP, like Linux and Unix, and has effect integrity and non-repudiation for a file.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.375-384
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• 2005

General purpose operating systems are Increasingly being used for serving time-sensitive applications. These applications require soft real-time characteristics from the kernel and from other system-level services. In this paper, we explore various operating systems techniques needed to support time-sensitive applications and describe the design of MUSMA(Multi-level Scheduler for Multimedia Application). MUSMA is a framework that combination of user-level top scheduler and kernel-level bottom scheduler. We develope MUSMA in linux environment and it's performance is evaluated. Experiment result shows that it is possible to satisfy the constraints of multimedia in a general purpose operating system without significantly compromising the performance of non-realtime applications.