• International journal of advanced smart convergence
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• v.11 no.2
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• pp.1-6
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• 2022

With the emergence of the new era of the 4th industrial revolution, compute-bound workloads with large memory footprint like big data processing increase dramatically. Even in such compute-bound workloads, however, we observe bulky I/Os while loading big data from storage to memory. Although file I/O cache plays a role of accelerating the performance of storage I/O, we found out that the cache hit rate in such environments is not improved even though we increase the file I/O cache capacity because of some special I/O references generated by compute-bound workloads. To cope with this situation, we propose a new file I/O cache management policy that improves the cache hit rate for compute-bound workloads significantly. Trace-driven simulations by replaying file I/O reference logs of compute-bound workloads show that the proposed cache management policy improves the cache hit rate compared to the well-acknowledged CLOCK algorithm by a large margin.

• Journal of Internet Computing and Services
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• v.4 no.2
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• pp.11-19
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• 2003

The technique which stores cache data in EXT2 or UFS designed for general purpose is not suitable for satisfying the speed required for web cache due to the general purpose file system. This study shows that there is the better solution by optimizing the file system using the characteristics of web file. It is impossible that the suggested RawCFS changes the size of cached object and the access authentication, and this results from the existence of up-to-dated object in the original server. This file system is proved in the capability test that it is faster than the technique by 40% which stores in each file by object unit. This can be used in the design of high end web server such as shoppingmall or Internet Broadcasting station which should provide objects like image or HTML as well as cache server to the client for the fast service.

• The KIPS Transactions:PartA
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• v.9A no.2
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• pp.163-170
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• 2002

Previous buffer cache schemes for continuous media file system only exploited the sequentiality of continuous media accesses and didn't consider looping references. However, in some video applications like foreign language learning, users mark the scene as loop area and then application automatically playbacks the scene several times. In this paper, we propose a novel buffer cache scheme for continuous media file system that sequential and looping references exist together. Proposed scheme increases the cache hit ratio by detecting reference pattern of files and appling an appropriate replacement policy to each file.

• The Journal of the Korea Contents Association
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• v.8 no.11
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• pp.57-64
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• 2008

The data grid computing provides geographically distributed storage resources to solve computational problems with large-scale data. Unlike cache replacement policies in virtual memory or web-caching replacement, an optimal file replacement policy for data grids is the one of the important problems by the fact that file size is very large. The traditional file replacement policies such as LRU(Least Recently Used), LCB-K(Least Cost Beneficial based on K), EBR(Economic-based cache replacement), LVCT(Least Value-based on Caching Time) have the problem that they have to predict requests or need additional resources to file replacement. To solve theses problems, this paper propose SBR-k(Sized-based replacement-k) that replaces files based on file size. The proposed policy considers file size to reduce the number of files corresponding to a requested file rather than forecasting the uncertain future for replacement. The results of the simulation show that hit ratio was similar when the cache size was small, but the proposed policy was superior to traditional policies when the cache size was large.

• Journal of KIISE
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• v.43 no.5
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• pp.524-530
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• 2016

The desire to access data faster and the growth of next-generation memories such as non-volatile memories, contribute to the development of research on memory file systems. It is recommended that memory mapped file I/O, which has less overhead than read-write I/O, is utilized in a high-performance memory file system. Memory mapped file I/O, however, brings a page table overhead, which becomes one of the big overheads that needs to be resolved in the entire file I/O performance. We find that same overheads occur unnecessarily, because a page table of a file is removed whenever a file is opened after being closed. To remove the duplicated overhead, we propose the mapping cache, a technique that does not delete a page table of a file but saves the page table to be reused when the mapping of the file is released. We demonstrate that mapping cache improves the performance of traditional file I/O by 2.8x and web server performance by 12%.

• Journal of Korea Multimedia Society
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• v.11 no.3
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• pp.404-413
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• 2008

As toward a ubiquitous society, a lot of methods have been proposed to protect personal privacy. Smart Cards with CPU and Memory are widely being used to implement the methods. The use of Java Card is also gradually getting expanded into more various applications. Because there is no standards in Java Card File System, Generally, Java Card File System follows the standards of Smart Card File System. However, one of disadvantages of the Java Card File System using a standard of Smart Card File System is that inefficient memory use and increasing processing time are caused by redundancy of data and program codes. In this paper, a File Cache method and a Direct Access method are proposed to solve the problems. The proposed methods are providing efficient memory use and reduced processing time by reduce a program codes.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.2
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• pp.66-74
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• 2008

Since modem embedded systems need to access, manipulate or store sensitive information, it requires being equipped with cryptographic file systems. However, cryptographic file systems result in poor performance so that they have not been widely adapted to embedded systems. Most cryptographic file systems degrade the performance unnecessarily because of system architecture. This paper proposes ISEA (Indexed and Separated Encryption Approach) that supports for encryption/decryption in system architecture and removes redundant performance loss. ISEA carries out encryption and decryption at different layers according to page cache layer. Encryption is carried out at lower layer than page cache layer while decryption at upper layer. ISEA stores the decrypted data in page cache so that it can be reused in followed I/O request without decryption. ISEA provides page-indexing which divides page cache into cipher blocks and manages it by a block. It decrypts pages partially so that it can eliminate unnecessary decryption. In synthesized experiment of read/write with various cache hit rates, it gives results suggesting that ISEA has improved the performance of encryption file system efficiently.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.155-160
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• 2018

In this paper, we found that buffer cache in general systems does not perform well in rendering software, and presented a new buffer cache management scheme that resolves this problem. To do so, we collected various file I/O traces of rending software and analyzed their characteristics. From this analysis, we observed that file I/Os in rendering consist of long loops, short loops, random accesses, and write-once accesses. Based on this observation, we presented a buffer cache management scheme that allocates cache space to each access types and manages them appropriately, thereby improving the buffer cache performances by 19% on average and up to 55%.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.129-134
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• 2015

This paper analyzes file access characteristics of smartphone apps and finds that a large portion of file writes are performed only once. Based on this observation, we present a new buffer cache management scheme that considers this characteristics. Buffer cache improves storage performance by maintaining hot file data in memory thereby servicing subsequent requests without storage accesses. However, it should flush modified data to storage in order to resist system crashes. The proposed scheme evicts cache data that has been written only once upon flushes, thus improving cache space utilization. Simulation experiments show that the proposed scheme improves cache hit ratio by 5-33% and power consumption by 27-92%.

• Journal of Information Technology Applications and Management
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• v.11 no.1
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• pp.189-200
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• 2004

Recently Flash Memory which is small and low-powered is widely used as a storage of embedded system, because an embedded system requests portability and a fast response. To resolve a difference of access time between a storage and RAM, Linux is using disk caching which copies a part of file on disk into RAM. It is not also an exception on embedded system. A READ access-time of flash memory is similar to RAMs. So, when a process on an embedded system reads data, it is similar to the time to access cached data in RAM and to access directly data on a flash memory. On the embedded system using limited memory, using a disk cache is that wastes much time and memory spaces to manage it and can not reflects the characteristic of a flash memory. This paper proposes the regular file access of limited using a page cache in the file system based on a flash memory and reflects the characteristic of a flash memory. The proposed algorithm minimizes power consumption because access numbers of the RAM are reduced and doesn't waste a memory space because it accesses directly to a flash memory Therefore, the performance improvement of the system applying the proposed algorithm is expected.