Recent discussions on increasing the efficiency of the Internet's infrastructure have centered on removing the shared Domain Name System (DNS) resolver and using a local resolver instead. In terms of the cache mechanism, this would involve removing the shared cache from the Internet. Although the removal of unnecessary parts tends to simplify the overall system, such a large configuration change would need to be analyzed before their actual removal. This paper presents our analysis on the effect of a shared DNS resolver based on campus network traffic. We found that (1) this removal can be expected to amplify the DNS traffic to the Internet by about 3.9 times, (2) the amplification ratio of the root DNS is much higher (about 6.3 times), and (3) removing all caching systems from the Internet is likely to amplify the DNS traffic by approximately 16.0 times. Thus, the removal of the shared DNS resolver is not a good idea. Our data analysis also revealed that (4) many clients without local caches generate queries repeatedly at short intervals and (5) deploying local caches is an attractive technique for easing DNS overhead because the amount of traffic from such clients is not small.

In content oriented networks (CON), routers in a network are generally equipped with local cache storages and store incoming contents temporarily. Efficient utilization of total cache storage in networks is one of the most important technical issues in CON, as it can reduce content server load, content download latency and network traffic. Performance of networked cache is reported to strongly depend on both cache decision and content request routing. In this paper, we evaluate several combinations of these two strategies. Especially for routing, we take up off-path cache routing, Breadcrumbs, as one of the content request routing proposals. Our performance evaluation results show that off-path cache routing, Breadcrumbs, suffers low performance with cache decisions which generally has high performance with shortest path routing (SPR), and obtains excellent performance with TERC (Transparent En-Route Cache) which is well-known to have low performance with widely used SPR. Our detailed evaluation results in two network environments, emerging CONs and conventional IP, show these insights hold in both of these two network environments.

Content-centric networking (CCN) promises efficient content delivery services with in-network caching. However, it cannot utilize cached chunks near users if they are not on the shortest path to the server, and it tends to mostly cache highly popular chunks in a domain. This degrades cache efficiency in obtaining various contents in CCN. Therefore, we propose hash-based cache distribution and search schemes to obtain various contents from nearby nodes and evaluate the effectiveness of this approach through simulation.

In this paper, we first evaluate Breadcrumbs in wireless multi-hop networks and reveal that they brings throughput improvement of not only popular content but also less popular content. Breadcrumbs can distribute popular content traffic towards edges of a wireless network, which enables low-popularity content to be downloaded from the gateway node. We also propose a new caching decision, called receiver caching. In receiver caching, only the receiver node caches the transmitted content. Our simulation results show that receiver caching prevents frequent replacement of cached content, which reduces invalid Breadcrumbs trails to be remained. And they also show that receiver caching significantly improves the total throughput performance of Breadcrumbs.

In-network guidance to off-path cache, Breadcrumbs, has been proposed for cache network. It guides content requests to off-path cached contents by using the latest content download direction pointer, breadcrumbs. In Breadcrumbs, breadcrumb pointer is overwritten when a new content download of the corresponding content passes through a router. There is a possibility that slightly old guidance information for popular contents might lead to better cached content than the latest one. In this paper, we propose a new in-network guidance, Multiple-Breadcrumbs, which holds old breadcrumbs even with the latest breadcrumb pointer generated with a new content download. We focus on its content search capability and propose Throughput Sensitive selection that selects the content source giving the best estimated throughput. Our performance evaluation gives interesting results that our proposed Multiple Breadcrumbs with Throughput Sensitive selection improves not only throughput for popular contents but also for unpopular contents.

Information-centric networking (ICN) has gained attention from network research communities due to its capability of efficient content dissemination. In-network caching function in ICN plays an important role to achieve the design motivation. However, many researchers on in-network caching due to its ability to efficiently disseminate content. The in-network caching function in ICN plays an important role in realizing the design goals. However, many in-network caching researchers have focused on where to cache rather than how to cache: the former is known as content deployment in the network and the latter is known as cache replacement in an ICN router. Although the cache replacement has been intensively researched in the context of web-caching and content delivery network previously, networks, the conventional approaches cannot be directly applied to ICN due to the fine granularity of chunks in ICN, which eventually changes the access patterns. In this paper, we argue that ICN requires a novel cache replacement algorithm to fulfill the requirements in the design of a high performance ICN router. Then, we propose a novel cache replacement algorithm to satisfy the requirements named Compact CLOCK with Adaptive Replacement (Compact CAR), which can reduce the consumption of cache memory to one-tenth compared to conventional approaches. In this paper, we argue that ICN requires a novel cache replacement algorithm to fulfill the requirements set for high performance ICN routers. Our solution, Compact CLOCK with Adaptive Replacement (Compact CAR), is a novel cache replacement algorithm that satisfies the requirements. The evaluation result shows that the consumption of cache memory required to achieve a desired performance can be reduced by 90% compared to conventional approaches such as FIFO and CLOCK.

Engineers and researchers have recently paid attention to Blockchain. Blockchain is a fault-tolerant distributed ledger without administrators. Blockchain is originally derived from cryptocurrency, but it is possible to be applied to other industries. Transferring digital asset is called a transaction. Blockchain holds all transactions, so the total amount of Blockchain data will increase as time proceeds. On the other hand, the number of Internet of Things (IoT) products has been increasing. It is difficult for IoT products to hold all Blockchain data because of their storage capacity. Therefore, they access Blockchain data via servers that have Blockchain data. However, if a lot of IoT products access Blockchain network via servers, server overloads will occur. Thus, it is useful to reduce workloads and improve throughput. In this paper, we propose a caching technique using a Field Programmable Gate Array-based (FPGA) Network Interface Card (NIC) which possesses four 10Gigabit Ethernet (10GbE) interfaces. The proposed system can reduce server overloads, because the FPGA NIC instead of the server responds to requests from IoT products if cache hits. We implemented the proposed hardware cache to achieve high throughput on NetFPGA-10G board. We counted the number of requests that the server or the FPGA NIC processed as an evaluation. As a result, the throughput improved by on average 1.97 times when hitting the cache.

CMOS microprocessors are limited in their capacity for clock speed improvement because of increasing computing power, i.e., they face a power-wall problem. Single-flux-quantum (SFQ) circuits offer a solution with their ultra-fast-speed and ultra-low-power natures. This paper introduces our contributions towards ultra-high-speed cryogenic SFQ computing. The first step is to design SFQ microprocessors. From qualitatively and quantitatively evaluating past-designed SFQ microprocessors, we have found that revisiting the architecture of SFQ microprocessors and on-chip caches is the first critical challenge. On the basis of cross-layer discussions and analysis, we came to the conclusion that a bit-parallel gate-level pipeline architecture is the best solution for SFQ designs. This paper summarizes our current research results targeting SFQ microprocessors and on-chip cache architectures.

Information-centric networking (ICN) has received increasing attention from all over the world. The novel aspects of ICN (e.g., the combination of caching, multicasting, and aggregating requests) is based on names that act as addresses for content. The communication with name has the potential to cope with the growing and complicating Internet technology, for example, Internet of Things, cloud computing, and a smart society. To realize ICN, router hardware must implement an innovative cache replacement algorithm that offers performance far superior to a simple policy-based algorithm while still operating with feasible computational and memory overhead. However, most previous studies on cache replacement policies in ICN have proposed policies that are too blunt to achieve significant performance improvement, such as first-in first-out (popularly, FIFO) and random policies, or impractical policies in a resource-restricted environment, such as least recently used (LRU). Thus, we propose CLOCK-Pro Using Switching Hash-tables (CUSH) as the suitable policy for network caching. CUSH can identify and keep popular content worth caching in a network environment. CUSH also employs CLOCK and hash-tables, which are low-overhead data structure, to satisfy the cost requirement. We numerically evaluate our proposed approach, showing that our proposal can achieve cache hits against the traffic traces that simple conventional algorithms hardly cause any hits.

Cache affinity has been proved to have great impact on the performance of packet processing applications on multi-core platforms. Flow-based packet scheduling can make the best of data cache affinity with flow associated data and context structures. However, little work on packet scheduling algorithms has been conducted when it comes to instruction cache (I-Cache) affinity in modified pipelining (MPL) architecture for multi-core systems. In this paper, we propose a protocol-aware packet scheduling (PAPS) algorithm aiming at maximizing I-Cache affinity at protocol dependent stages in MPL architecture for multi-protocol processing (MPP) scenario. The characteristics of applications in MPL are analyzed and a mapping model is introduced to illustrate the procedure of MPP. Besides, a stage processing time model for MPL is presented based on the analysis of multi-core cache hierarchy. PAPS is a kind of flow-based packet scheduling algorithm and it schedules flows in consideration of both application-level protocol of flows and load balancing. Experiments demonstrate that PAPS outperforms the Round Robin algorithm and the HRW-based (HRW) algorithm for MPP applications. In particular, PAPS can eliminate all I-Cache misses at protocol dependent stage and reduce the average CPU cycle consumption per packet by more than 10% in comparison with HRW.

Load size for a service on the Internet changes remarkably every hour. Thus, it is expected for service system scales to change dynamically according to load size. KVS (key-value store) is a scalable DBMS (database management system) widely used in largescale Internet services. In this paper, we focus on Cassandra, a popular open-source KVS implementation, and discuss methods for improving dynamic scaling performance. First, we evaluate node joining time, which is the time to complete adding a node to a running KVS system, and show that its bottleneck process is disk I/O. Second, we analyze disk accesses in the nodes and indicate that some heavily accessed files cause a large number of disk accesses. Third, we propose two methods for improving elasticity, which means decreasing node adding and removing time, of Cassandra. One method reduces disk accesses significantly by keeping the heavily accessed file in the page cache. The other method optimizes I/O scheduler behavior. Lastly, we evaluate elasticity of our methods. Our experimental results demonstrate that the methods can improve the scaling-up and scaling-down performance of Cassandra.

We propose a cache-aware method to accelerate texture-based volume rendering on a graphics processing unit (GPU) that is compatible with the compute unified device architecture. The proposed method extends a previous method such that it can maximize the average rendering performance while rotating the viewing direction around a volume. To realize this, the proposed method performs in-place rotation of volume data, which rearranges the order of voxels to allow consecutive threads (warps) to refer to voxels with the minimum access strides. Experiments indicate that the proposed method replaces the worst texture cache (TC) hit rate of 42% with the best TC hit rate of 93% for a 10243-voxel volume. Thus, the average frame rate increases by a factor of 1.6 in the proposed method compared with that in the previous method. Although the overhead of in-place rotation slightly decreases the frame rate from 2.0 frames per second (fps) to 1.9 fps, this slowdown occurs only with a few viewing directions.

An 8-issue superscalar core generally requires a 24-port RAM for the register file. The area and energy consumption of a multiported RAM increase in proportional to the square of the number of ports. A register cache can reduce the area and energy consumption of the register file. However, earlier register cache systems suffer from lower IPC caused by register cache misses. Thus, we proposed the Non-Latency-Oriented Register Cache System (NORCS) to solve the IPC problem with a modified pipeline. We evaluated NORCS mainly from the viewpoint of microarchitecture in the original article, and showed that NORCS maintains almost the same IPC as conventional register files. Researchers in NVIDIA adopted the same idea for their GPUs. However, the evaluation was not sufficient from the viewpoint of LSI design. In the original article, we used CACTI to evaluate the area and energy consumption. CACTI is a design space exploration tool for cache design, and adopts some rough approximations. Therefore, this paper shows design of NORCS with FreePDK45, an open source process design kit for 45nm technology. We performed manual layout of the memory cells and arrays of NORCS, and executed SPICE simulation with RC parasitics extracted from the layout. The results show that, from a full-port register file, an 8-entry NORCS achieves a 75.2% and 48.2% reduction in area and energy consumption, respectively. The results also include the latency which we did not present in our original article. The latencies of critical path is 307ps and 318ps for an 8-entry NORCS and a conventional multiported register file, respectively, when the same two cycles are allocated to register file read.

Communication infrastructures under the influence of the disaster strike, e.g., earthquake, will be partitioned due to the significant damage of network components such as base stations. The communication model of the Internet bases on a location-oriented ID, i.e., IP address, and depends on the DNS (Domain Name System) for name resolution. Therefore such damage remarkably deprives the reachability to the information. To achieve robustness of information retrieval in disaster situation, we try to apply CCN/NDN (Content-Centric Networking/Named-Data Networking) to information networks fragmented by the disaster strike. However, existing retransmission control in CCN is not suitable for the fragmented networks with intermittent links due to the timer-based end-to-end behavior. Also, the intermittent links cause a problem for cache behavior. In order to resolve these technical issues, we propose a new packet forwarding scheme with the dynamic routing protocol which resolves retransmission control problem and cache control scheme suitable for the fragmented networks. Our simulation results reveal that the proposed caching scheme can stably store popular contents into cache storages of routers and improve cache hit ratio. And they also reveal that our proposed packet forwarding method significantly improves traffic load, energy consumption and content retrieval delay in fragmented networks.

This paper proposes a cache-aware optimization method to accelerate out-of-core cone beam computed tomography reconstruction on a graphics processing unit (GPU) device. Our proposed method extends a previous method by increasing the cache hit rate so as to speed up the reconstruction of high-resolution volumes that exceed the capacity of device memory. More specifically, our approach accelerates the well-known Feldkamp-Davis-Kress algorithm by utilizing the following three strategies: (1) a loop organization strategy that identifies the best tradeoff point between the cache hit rate and the number of off-chip memory accesses; (2) a data structure that exploits high locality within a layered texture; and (3) a fully pipelined strategy for hiding file input/output (I/O) time with GPU execution and data transfer times. We implement our proposed method on NVIDIA's latest Maxwell architecture and provide tuning guidelines for adjusting the execution parameters, which include the granularity and shape of thread blocks as well as the granularity of I/O data to be streamed through the pipeline, which maximizes reconstruction performance. Our experimental results show that it took less than three minutes to reconstruct a 20483-voxel volume from 1200 20482-pixel projection images on a single GPU; this translates to a speedup of approximately 1.47 as compared to the previous method.

Information-Centric Networking (ICN) technology has recently been attracting substantial interest in the research community as one of the most promising future Internet architectures. The Named Data Networking (NDN) approach, which is one of the most recent instantiations of the ICN approach, would be a good choice for multimedia services, because NDN utilizes in-network storage embedded in NDN routers by caching recently or frequently requested contents. It is important to determine which data to cache at which NDN routers in order to achieve high performance, by considering not only the popularity of contents but also the inter-chunk popularity of a content item. This paper presents a chunk-block-based incremental caching scheme that considers both content and inter-chunk popularity. Our proposed scheme employs an incremental cache populating mechanism, which utilizes not only core-side but also edge-side NDN routers according to the request rate of the content item. Through simulations, we show that the proposed scheme achieves less delay, reduced redundant network traffic, and a higher cache hit ratio than legacy schemes.

In this work, we propose general, practical and accurate models to analyze the performance of multi-cache systems, in which a cache forwards its miss stream (i.e., requests which have not found the target item) to other caches. We extend a miss stream modeling technique originally known as Melazzi's approximation, which provides a simple but accurate approximate analysis for caches with cascade configurations. We consider several practical replication strategies, which have been commonly adopted in the context of ICN, taking into account the effects of temporal locality. Also, we capture the existing state correlations between neighboring caches by exploiting the cache eviction time. Our proposed models to handle traffic patterns allow us to go beyond the standard Poisson approximation under Independent Reference Model. Our results, validated against simulations, provide interesting insights into the performance of multi-cache systems with different replication strategies.

In the most recent processor designs, memory access latency is shortened by adopting a memory hierarchy. In this configuration, the memory consists of a main memory, which comprises dynamic random-access memory (DRAM), and a cache memory, which consists of static random-access memory (SRAM). A cache memory, which is now used in increasingly large volumes, accounts for a vast proportion of the energy consumption of the overall processor. There are two ways to reduce the energy consumption of the cache memory: by decreasing the number of accesses, and by minimizing the energy consumed per access. In this study, we reduce the size of the L1 cache by compressing frequent bit sequences, thus cutting the energy consumed per access. A “frequent bit sequence” is a specific bit pattern that often appears in high-order bits of data retained in the cache memory. Our proposed mechanism, which is based on measurements using a software simulator, cuts energy consumption by 41.0% on average as compared with conventional mechanisms.

Content oriented network is expected to be one of the most promising approaches for resolving design concept difference between content oriented network services and location oriented architecture of current network infrastructure. There have been proposed several content oriented network architectures, but research efforts for content oriented networks have just started and technical issues to be resolved are still remained. Because of content oriented feature, content data transmitted in a network can be reused by content requests from other users. Pervasive cache is one of the most important benefits brought by the content oriented network architecture, which forms interconnected caching networks. Caching network is the hottest research area and lots of research activities have been published. This paper surveys recent research activities for caching networks in content oriented networks, with focusing on important factors which affect caching network performance, i.e. content request routing, caching decision, and replacement policy of cache. And this paper also discusses future direction of caching network researches.

These days, in addition to host-to-host communication, Information-Centric Network (ICN) has emerged to reflect current content-centric network usage, based on the fact that many users are now interested not in where contents are but in acquired contents themselves. However, current IP network must still remain, at least from deployment perspective, as one of near future network architectures. This is because ICN has various scalability and feasibility challenges, and host-to-host communication is also diffused like remote login, VoIP, and so on. Therefore, the authors aim to establish the feature of ICN on conventional IP network to achieve feasible and efficient architecture. We consider that, as a feasible and efficient architecture, only user-edges keep some contents' caches within their computational and bandwidth limitations and contents should be replicated also on some replica servers dispersedly to assure contents' distribution even if user caches are not found. To achieve this, in this paper, we propose to operate Content Delivery Network (CDN) and Breadcrumbs (BC) frameworks coordinately on IP network. Both CDN and BC are important as a content-centric technique. In CDN, replica servers called surrogates are placed dispersedly in all over the Internet. Although this provides users with contents from nearer surrogate servers, the surrogate servers have higher workload to distribute contents to many users. In the proposed method, in cooperation with BC method that is proposed to implement ICN on IP network, the surrogate server workload is drastically reduced without largely increasing hop count for content delivery. Although it needs some functions to implement our approach such as adopting BC architecture to routers, calculating and reporting information required for cooperation of BC method with CDN, the cost for the functions in our solution is not so significant. Finally, we evaluate the proposed method with CDN we carefully modeled through simulation.