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An analytical model for the performance evaluation of stack-based Web cache replacement algorithms

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS 2010年第1期23卷 1-22页

作者： Messaoud, S. Youssef, H. Univ Sousse PRINCE Res Unit Inst Super Informat & Technol Commun Hammam Sousse 4011 Tunisia

Web caching has been the solution of choice to web latency problems. The efficiency of a Web cache is strongly affected by the replacement algorithm used to decide which objects to evict once the cache is saturated. Numerous web cache replacement algorithms have appeared in the literature. Despite their diversity, a large number of them belong to a class known as stack-based algorithms. These algorithms are evaluated mainly via trace-driven simulation. The very few analytical models reported in the literature were targeted at one particular replacement algorithm, namely least recently used (LRU) or least frequently used (LFU). Further they provide a formula for the evaluation of the Hit Ratio only. The main contribution of this paper is an analytical model for the performance evaluation of any stack-based web cache replacement algorithm. The model provides formulae for the prediction of the object Hit Ratio, the byte Hit Ratio, and the delay saving ratio. The model is validated against extensive discrete event trace-driven simulations of the three popular stack-based algorithms, LRU, LFU, and SIZE, using NLANR and DEC traces. Results show that the analytical model achieves very good accuracy. The mean error deviation between analytical and simulation results is at most 6% for LRU, 6% for the LFU, and 10% for the SIZE stack-based algorithms. Copyright (C) 2009 John Wiley & Sons, Ltd.

关键词： Web caching replacement algorithms stack algorithms performance evaluation

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Efficient Pair of replacement algorithms for L1 and L2 Cache for Matrix Multiplication

Efficient Pair of Replacement Algorithms for L1 and L2 Cache...

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IEEE International Advance Computing Conference

作者： Gupta, Richa Tokekar, Sanjiv Acropolis Inst Technol & Res Indore Madhya Pradesh India DAVV IET Elect & Telecom Engn Indore India

ISBN: (纸本)9781424429271

Processors speed is much faster than memory;to bridge this gap cache memory is used. This paper proposes a preeminent pair of replacement algorithms for Level 1 cache (L 1) and Level 2 cache (L2) respectively for the Matrix Multiplication (MM) application. The access patterns of L I and L2 are different, when CPU not gets the desired data in L1 then it goes to L2. Thus the replacement algorithm which works efficiently for L1 may not be efficient for L2. With the reference string of MM the paper has analyzed the behavior of various existing replacement algorithms at L1 and L2 respectively. The replacement algorithms which are taken into consideration are: Least Recently Used (LRU), Least Frequently Used (LFU) and First In First Out (FIFO). This paper has also proposed new replacement algorithms for L1 (NEW ALGO1) and for L2 (NEW ALGO2) respectively for the same application. Analysis shows that by applying these algorithms at L1 and L2 respectively miss rates are considerably reduced.

关键词： Level 1 Cache (L1) Level 2 Cache (L2) replacement algorithms Access Pattern Matrix Multiplication (MM)

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2Q*: an effective, low-overhead, improved replacement algorithm for mail service applications in storage system

2Q*: an effective, low-overhead, improved replacement algori...

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IEEE International Symposium on Parallel and Distributed Processing with Applications (ISPA)

作者： Si, Chengxiang Meng, Xiaoxuan Xu, Lu Coordinat Ctr China Natl Comp Network Emergency Response Tech Team Beijing Peoples R China Chinese Acad Sci Inst Comp Technol Beijing Peoples R China

Any one algorithm cannot be effective for all applications;therefore, choosing one appropriate for one special application is very meaningful. In this article, we analyzed access patterns for mail service application, and acquired an algorithm appropriate for it. Moreover, based on analysis of performance characteristics for the current algorithm, we proposed an improved algorithm, called 2Q*, which behaves better than others for a full range of sizes. We also verify the effectiveness of 2Q* in a real buffer system, and join it with the main stream pre-fetch policy. The experimental results show that 2Q* can improve IO performance of mail service application effectively.

关键词： cache replacement algorithms mail service

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2Q*: an effective, low-overhead, improved replacement algorithm for mail service applications in storage system

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JOURNAL OF THE CHINESE INSTITUTE OF ENGINEERS 2013年第1期36卷 63-73页

作者： Si, Chengxiang Meng, Xiaoxuan Xu, Lu Coordinat Ctr China Natl Comp Network Emergency Response Tech Team Beijing Peoples R China Chinese Acad Sci Inst Comp Technol Beijing Peoples R China

关键词： cache replacement algorithms mail service

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Low-overhead decision support for dynamic buffer reallocation

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COMPUTER SCIENCE-RESEARCH AND DEVELOPMENT 2012年第1期27卷 29-43页

作者： Schmidt, Karsten Baechle, Sebastian Univ Kaiserslautern Dept Comp Sci Kaiserslautern Germany

Effective I/O buffering is a performance-critical task in database management systems. Accordingly, systems usually employ various special-purpose buffers to align, e.g., device speed, page size, and replacement policies with the actual data and workload. However, such partitioning of available buffer memory results in complex optimization problems for database administrators and also in fragile configurations which quickly deteriorate on workload shifts. Reliable forecasts of I/O costs enable a system to evaluate alternative configurations to continuously optimize its buffer memory allocation at runtime. So far, all techniques proposed for the prediction of buffer performance focus solely on hit ratio gains for increased buffer sizes to identify buffers which promise the greatest benefit. These approaches, however, assume that their forecast allows to extrapolate the effect for buffer downsizing, too. As we will show, this comes along with a severe risk of wrong tuning decisions, which may heavily impact system performance. Thus, we emphasize the importance of reliably forecasting the penalty to expect for shrinking buffers in favor of others. We explore the use of lightweight extensions for widely used buffer algorithms to perform on-the-fly simulation of buffer performance of smaller and larger buffer sizes simultaneously. Furthermore, we present a simple cost model and demonstrate how to compose these concepts into a self-tuning component for dynamic buffer reallocation.

关键词： Self-tuning Buffer reallocation Forecasting replacement algorithms

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Analysis of web-proxy cache replacement algorithms under steady-state conditions

Analysis of web-proxy cache replacement algorithms under ste...

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3rd International Conference on Web Information Systems and Technologies

作者： Cardenas, L. G. Pont, A. Sahuquillo, J. Gil, J. A. Univ Polytecn Valencia Dept Comp Engn Camino Vera S-N Valencia 46071 Spain

ISBN: (纸本)9789728865771

Web-Proxy servers are used to reduce the bandwidth consumption and users' perceived latency while navigating the WWW, by caching the most frequent objects accessed by users. Since they were introduced, most of the evaluations studies related to Web-Proxy caches have focused on the replacement algorithms performance using simulation techniques. But few of them have been done assuring the representativeness of the studies and considering real traces and cache sizes. This paper describes a methodology that permits fair performance comparison studies of replacement algorithms, that is, the system reaches the steady-state and the results are provided showing narrow confidence intervals. An experimental evaluation study applying this methodology is also presented. The study uses a trace-driven simulation framework, real traces containing more than one hundred million of user's requests, and compares three replacement algorithms implemented in actual Web-Proxy caches.

关键词： performance evaluation simulation proxy-web replacement algorithms

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An effective, low-overhead, improved replacement algorithm for mail service applications in storage system

An effective, low-overhead, improved replacement algorithm f...

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IEEE International Symposium on Parallel and Distributed Processing With Applications

作者： Si, Chengxiang Meng, Xiaoxuan Chen, Yuanfei Xu, Lu Institute of Computing Technology Chinese Academy of Sciences Graduate School of the Chinese Academy of Sciences Beijing China Institute of Computing Technology Chinese Academy of Sciences Beijing China

ISBN: (纸本)9780769541907

This paper analyzed the performance characteristics of classic 2Q algorithm when it was performed on mail-service workloads, and proposes an improved algorithm, called 2Q*. The simulation results show that 2Q* algorithm can outperform the other replacement algorithms, including the classic 2Q algorithm, for all the cache sizes and various mail-service workloads. To verify the simulation results in real system, we integrated the algorithm into FlexiCache, a partitioned buffer cache system, and joined it with a popular adaptive sequential pre-fetch policy properly. The experiment results verify the effectiveness of 2Q* algorithm for mail service applications. By joint with the prefetch policy, the performance is further improved. Moreover, its runtime overhead is also fairly low. © 2010 IEEE.

关键词： 2Q algorithm FlexiCache cache cache storage electronic mail mail service mail service applications partitioned buffer cache system prefetch policy replacement algorithm replacement algorithms storage system

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RACE: A robust adaptive caching strategy for buffer cache

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IEEE TRANSACTIONS ON COMPUTERS 2008年第1期57卷 25-40页

作者： Zhu, Yifeng Jiang, Hong Univ Maine Dept Elect & Comp Engn Orono ME 04469 USA Univ Nebraska Dept Comp Sci Lincoln NE 68588 USA

Although many block replacement algorithms for buffer caches have been proposed to address the well- known drawbacks of the LRU algorithm, they are not robust and cannot maintain a consistent performance improvement over all workloads. This paper proposes a novel and simple replacement scheme, called the Robust Adaptive buffer Cache management schemE ( RACE), which differentiates the locality of I/ O streams by actively detecting access patterns that are inherently exhibited in two correlated spaces, that is, the discrete block space of program contexts from which I/ O requests are issued and the continuous block space within files to which I/ O requests are addressed. This scheme combines the global I/ O regularities of an application and the local I/ O regularities of individual files that are accessed in that application to accurately estimate the locality strength, which is crucial in deciding which blocks are to be replaced upon a cache miss. Through comprehensive simulations on 10 real- application traces, RACE is shown to have higher hit ratios than LRU and all other state- of- the- art cache management schemes studied in this paper.

关键词： operating systems file systems management memory management replacement algorithms

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Practically realizable efficient data allocation and replication strategies for distributed databases with buffer constraints

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IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 2006年第9期17卷 1001-1013页

作者： Gu, Xin Lin, Wujuan Veeravalli, Bharadwaj Siemens Ltd Beijing 100102 Peoples R China Data Storage Inst Singapore 117608 Singapore Natl Univ Singapore Dept Elect & Comp Engn Singapore 117576 Singapore

In this paper, we address the performance of distributed database systems with buffer constraints. Specifically, our objective is to design and analyze efficient data allocation and replication strategies to minimize the total servicing cost for an arbitrary read/write request sequence, under finite buffer constraints of the nodes in the system. When the available buffer space in a node is not enough to store a copy of an object, the decision has to be made on whether or not we should evict one or more objects in use to give room for the new object copy. In this paper, we design and analyze the data replication strategies with the model of Dynamic Window Mechanism (DWM) algorithm jointly implemented with different types of object replacement strategies ( No replacement, LRU, and LFU) commonly found in practice. We consider situations wherein the object sizes are identical as well as heterogeneous. We will show the impact on the performance of the allocation and replication strategies due to the limited local database buffer capacities. We analyze and quantify theoretically ( using competitive analysis) the performances of all the proposed algorithms. Further, we perform rigorous simulation experiments to validate the findings with respect to several influencing parameters. Several useful conclusions are drawn based on the experimental results and we highlight the usefulness of the algorithms under different situations.

关键词： object allocation distributed database system competitiveness replacement algorithms caching communication cost

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Making LRU friendly to weak locality workloads: A novel replacement algorithm to improve buffer cache performance

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IEEE TRANSACTIONS ON COMPUTERS 2005年第8期54卷 939-952页

作者： Jiang, S Zhang, XD Los Alamos Natl Lab Performance & Architecture Grp Los Alamos NM 87545 USA Coll William & Mary Dept Comp Sci Williamsburg VA 23187 USA

Although the LRU replacement algorithm has been widely used in buffer cache management, it is well-known for its inability to cope with access patterns with weak locality. Previously proposed algorithms to improve LRU greatly increase complexity and/or cannot provide consistently improved performance. Some of the algorithms only address LRU problems on certain specific and predefined cases. Motivated by the limitations of existing algorithms, we propose a general and efficient replacement algorithm, called Low Inter-reference Recency Set (LIRS). LIRS effectively addresses the limitations of LRU by using recency to evaluate Inter-Reference Recency (IRR) of accessed blocks for making a replacement decision. This is in contrast to what LRU does: directly using recency to predict the next reference time. Meanwhile, LIRS mostly retains the simple assumption adopted by LRU for predicting future block access behaviors. Conducting simulations with a variety of traces of different access patterns and with a wide range of cache sizes, we show that LIRS significantly outperforms LRU and outperforms other existing replacement algorithms in most cases. Furthermore, we show that the additional cost for implementing LIRS is trivial in comparison with that of LRU. We also show that the LIRS algorithm can be extended into a family of replacement algorithms, in which LRU is a special member.

关键词： operating systems memory management replacement algorithms

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