• The KIPS Transactions:PartD
• /
• v.14D no.4 s.114
• /
• pp.447-458
• /
• 2007

The objective of this study is to provide faster mobile web service by improving performance of Contents Cache used for mobile web service in the existing Mobile Gate System. It was found that two elements existed in Mark-Up page transcoded by Contents Generator. One of the elements was dependent only on the requested DIDL page and Mark-Up type. The other was dependent on each of the requested DIDL page, Mark-Up type, size of mobile display 모바일 장치 to request service, type of images available and color depth count of the images available. The conventional Contents Cache saved the entire Mark-Up page to hold both of the two elements. This caused the problem where storage space was not effectively used because reusable elements were repetitively saved in cache memory domain due to change in one of the elements even though all the other elements were the same. As a result, a larger number of transcoded Mark-Up pages could not be saved in the same cache memory size. Therefore, in this study, Mark-Up pages transcoded by Contents Generator were divided into two elements and were separately saved. Also, in order to respond to the demand for replacing data in cache with new data, this study applied two algorithms of LFU and LRU. This study proposed the method to implement cache performance of faster speed by enabling to save more number of the transcoded Mark-Up pages in the same cache storage space.

• Journal of KIISE:Computing Practices and Letters
• /
• v.14 no.7
• /
• pp.669-679
• /
• 2008

With the increasing demands of information sharing and searches via the web, the web search engine has drawn much attention. Although many researches have been done to solve technical challenges to build the web search engine, the issue regarding its query processing system is rarely dealt with. Since the software architecture and operational schemes of the query processing system are hard to elaborate, we here present related techniques implemented on a commercial system. The implemented system is a very large-scale system that can process 5-million user queries per day by using index files built on about 65-million web pages. We implement a multi-level cache scheme to save already returned query results for performance considerations, and the multi-level cache is managed in 4-level cache storage areas. Using the multi-level cache, we can improve the system throughput by a factor of 4, thereby reducing around 70% of the server cost.

• Journal of Communications and Networks
• /
• v.8 no.3
• /
• pp.330-338
• /
• 2006

Many web cache systems and policies concerning them have been proposed. These studies, however, consider large objects less useful than small objects in terms of performance, and evict them as soon as possible. Even if this approach increases the hit rate, the byte hit rate decreases and the connections occurring over congested links to outside networks waste more bandwidth in obtaining large objects. This paper puts forth a client-cluster approach for improving the web cache system. The client-cluster is composed of the residual resources of clients and utilizes them as exclusive storage for large objects. This proposed system achieves not only a high hit rate but also a high byte hit rate, while reducing outgoing traffic. The distributed hash table (DHT) based peer-to-peer lookup protocol is utilized to manage the client-cluster. With the natural characteristics of this protocol, the proposed system with the client-cluster is self-organizing, fault-tolerant, well-balanced, and scalable. Additionally, the large objects are managed with an index based allocation method, which balances the loads of all clients well. The performance of the cache system is examined via a trace driven simulation and an effective enhancement of the proxy cache performance is demonstrated.

• Journal of Convergence for Information Technology
• /
• v.9 no.2
• /
• pp.17-22
• /
• 2019

Cache is a technique that improves the client's response time, thereby reducing the bandwidth and showing an effective side. However, there are vulnerabilities in the cache technique as well as in some techniques. Web caching is convenient, but it can be exploited by hacking and cause problems. Web cache problems are mainly caused by cache misses and excessive cache line fetch. If the cache miss is high and excessive, the cache will become a vulnerability, causing errors such as transforming the secure data and causing problems for both the client and the system of the user. If the user is aware of the cache infection and the countermeasure against the error, the user will no longer feel the cache error or the problem of the infection occurrence. Therefore, this study proposed countermeasures against four kinds of cache infections and errors, and suggested countermeasures against web cache infections.

• KIPS Transactions on Computer and Communication Systems
• /
• v.1 no.1
• /
• pp.1-10
• /
• 2012

The way-lookup cache and the way-tracking cache are considered to be the most energy-efficient when used for level 1 and level 2 caches, respectively. This paper proposes an energy-efficient set-associative cache using the bi-mode way-selector that combines the way selecting techniques of the way-tracking cache and the way-lookup cache. The simulation results using an Alpha 21264-based system show that the bi-mode way-selecting L1 instruction cache consumes 27.57% of the energy consumed by the conventional set-associative cache and that it is as energy-efficient as the way-lookup cache when used for L1 instruction cache. The bi-mode way-selecting L1 data cache consumes 28.42% of the energy consumed by the conventional set-associative cache, which means that it is more energy-efficient than the way-lookup cache by 15.54% when used for L1 data cache. The bi-mode way-selecting L2 cache consumes 15.41% of the energy consumed by the conventional set-associative cache, which means that it is more energy-efficient than the way-tracking cache by 16.16% when used for unified L2 cache. These results show that the proposed cache can provide the best level of energy-efficiency regardless of the cache level.

• Journal of KIISE
• /
• v.44 no.7
• /
• pp.658-667
• /
• 2017

The demand for large-scale storage systems has continued to grow due to the emergence of multimedia, social-network, and big-data services. In order to improve the response time and reduce the load of such large-scale storage systems, DRAM-based in-memory cache systems are becoming popular. However, the high cost of DRAM severely restricts their capacity. While the method of compressing cache entries has been proposed to deal with the capacity limitation issue, compression and decompression, which are technically difficult to parallelize, induce significant processing overhead and in turn retard the response time. A selective compression scheme is proposed in this paper for in-memory file system caches that rapidly estimates the compression ratio of incoming cache entries with their Shannon entropies and compresses cache entries with low compression ratio. In addition, a description is provided of the design and implementation of an in-kernel in-memory file system cache with the proposed selective compression scheme. The evaluation showed that the proposed scheme reduced the execution time of benchmarks by approximately 18% in comparison to the conventional non-compressing in-memory cache scheme. It also provided a cache hit ratio similar to the all-compressing counterpart and reduced 7.5% of the execution time by reducing the compression overhead. In addition, it was shown that the selective compression scheme can reduce the CPU time used for compression by 28% compared to the case of the all-compressing scheme.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.11
• /
• pp.3116-3123
• /
• 1999

Current disk systems are generally designed to reduce read traffic more effectively. Hence, write traffic of the I/O workload could potentially become a bottleneck of the disk system performance. In order to overcome this problem without much cost, this paper presents using outermost-zone track of multi-zoned recording disk as a secondary disk cache. The proposed disk cache improves the disk system performance by following exploitations: speed difference between block transfer and track transfer, difference in transfer rate between outermost-zone tracks and inner tracks, reduction in the seek time caused by decreasing the number of disk cache tracks, and idle period during burst accesses. In addition, it does not waste the disk space because it allocates the caching space by the cylinder unit. The simulation results show that the proposed system improves 2.54∼3.11 times better in terms of average response time for write operations than existing disk systems..

• Proceedings of the Korea Information Processing Society Conference
• /
• 2003.11b
• /
• pp.1007-1010
• /
• 2003

Efficient using of web cache is becoming important factor that decide system management efficiency in web-Based system. Cache performance depends heavily on replacement algorithms, which dynamically select a suitable subset of objects for caching in a finite space. However, replacement algorithm on web cache has many differences than traditional replacement algorithm. In this paper, a web-caching algorithm is proposed for efficient operation of web base system. The algorithm is designed based on a divided scope that considered size reference characteristic and heterogeneity on web object. The performance of the algorithm is analyzed with an experiment. With the experiment results, the algorithm is compared with previous replacement algorithms, and its performance is confirmed ith an improvement of response speed.

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

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.48 no.4
• /
• pp.1-8
• /
• 2011

Traditional transactional memory systems are no longer able to guarantee the performance of diverse applications with overflowed transactions since there is the drawback that tracking the data for logging is difficult. Especially, this mechanism has a disadvantage of increasing communication delay for sustaining the state which is required to detect the conflict on the overflowed transactions from the first level cache in the transactional memory systems. To address this point, we have focused on the cache architecture of the systems to reduce the overhead caused by overflows and cache misses. In this paper, we present Supportive Cache which reduces additional overhead during transactions. Supportive Cache performs a parallel look-up with L1 private cache and uses the same replacement policy as L1 private cache. We evaluate the performance of the proposed design by comparing LogTM-SE with and without Supportive Cache. The simulation results show that our system improves the performance by 37% on average, compared to the original LogTM-SE which uses the same hardware resource.