Some results on the classification of N objects in M classes with at least c objects in each class

In the realm of modern computing, cache memory serves as an essential intermediary, mitigating the speed disparity between rapid processors and slower main memory. Central to this study is the development of an innovative cache controller for a 4-way set associative cache, meticulously crafted using VHDL and structured as a Finite State Machine. This controller efficiently oversees a cache of 256 bytes, with each block encompassing 128 bits or 16 bytes, organized into four sets containing four lines each. A key feature of this design is the incorporation of the Tree Pseudo Least Recently Used (PLRU) algorithm for cache replacement, a strategic choice aimed at optimizing cache performance. The effectiveness of this controller was rigorously evaluated using ModelSim, which generated a comprehensive timing diagram to validate the design's functionality, especially when integrated with a segmented main memory of four 1KB banks. The results from this evaluation were promising, showcasing precise logic outputs within the timing diagram. Operational efficiency was evidenced by the controller's swift processing speeds: read hits were completed in a mere three cycles, read misses in five and a half cycles, and both write hits and misses in three and a half cycles. These findings highlight the controller's capability to enhance cache memory efficiency, striking a balance between the complexities of set-associative mapping and the need for optimized performance in contemporary computing systems. This study not only demonstrates the potential of the proposed cache controller design in bridging the processor-memory speed gap but also contributes significantly to the field of cache memory management by offering a viable solution to the challenges posed by traditional cache configurations.

Cache memories have proven their effectiveness in the von Neumann architecture when localities of reference govern the execution loci of programs. A pure dataflow program, in contrast, contains no locality of reference since the execution sequence is enforced only by the availability of arguments. Instruction locality may be enhanced if, dataflow programs are reordered. Enhancing the locality of data references in the dataflow architecture is a more challenging problem. In this paper we report our approaches to the design of instruction, data (operand) and I-Structure cache memories using the Explicit Token Store (ETS) model of dataflow systems. We will present the performance results obtained using various benchmark programs.

Two performance gaps in the memory hierarchy, between CPU cache and main memory, and main memory and mass storage, will become increasingly severe bottlenecks for computing-system performance. Although it is necessary to increase memory capacity to fill these gaps, power also increases when conventional volatile memories are used. A new nonvolatile memory for this purpose has been anticipated. Storage class memory is used to fill the second gap. Many candidates exist: ReRAM, PRAM, and 3D-cross point type with resistive change RAM. However, nonvolatile last level cache (LLC) is used to fill the first gap. Advanced STT-MRAM has achieved sub-4ns read and write accesses with perpendicular magnetic tunnel junctions (p-MTJ) [1–2]. Furthermore, mature integration processes have been developed and 8Mb STT-MRAM with sub-5ns operation has shown high reliability [3]. Moreover, because of its non-volatility, STT-MRAM can reduce operation energy by more than 81% compared to SRAM for cache [1]. This paper presents STT-MRAM-based last level cache memory (LLC) including MRAM memory core, peripherals and cache logic circuits, using novel power optimization with high-speed power gating (HS-PG),considering processor architectures and cache memory accesses. The STT-MRAM-based cache has high reliability to reduce the write-error rate with novel write-verify-write. Furthermore, a read-modify-write scheme is implemented to reduce active power without penalty. Figure 7.2.1 presents a block diagram of a 4Mb STT-MRAM based cache.

Neural networks and image processing algorithms typically use very large amounts of data and usually this data is processed iteratively. Hence, the issue of cache memories for enhancing the processing speed is important. A particularly important model that fits these applications is the simple loop model. Here, the exact solution for the cache memory simple loop model under random replacement is given using an urn model and the theory of Markov chains. The probability distribution is obtained as a quotient of Stirling Numbers of the Second Kind. It is also shown that asymptotically the number of elements in the urns follows a Truncated at Zero Poisson Distribution.

A CMOS VLSI cache memory subsystem that includes a 72 K-bit cache memory, an 11 K-bit tag memory, a 1.3 K-bit state array, two special buffers and cache control logic, has been designed and integrated on a microprocessor chip. The architecture, design and analysis of the cache design are presented. The design achieves higher system performance by reducing the cache reload penalty through a pseudo-two-port architecture which utilizes a reload buffer and a store-back buffer. It also maintains cache data coherency and supports multiprocessing by bus snooping. A single-port tag is used for concurrent snooping and CPU access with an enhanced write-once protocol. A cost-effective 'locked replacement' scheme was incorporated to maintain data coherency in these two special buffers. Cache modeling and analysis were carried out to derive the proper design point. >

The recent advance in dataflow processing - to combine the dataflow paradigm with the control flow paradigm - has brought out many new challenging issues. This hybrid organization has made it possible to study familiar control flow concepts within the framework of the dataflow architecture. The concept of cache memory has proven its effectiveness in the von Neumann architecture due to the spatial and temporal localities which govern the organization of the conventional programming environment. A dataflow paradigm, does not imply to the locality. However, dataflow programs can be reordered to enhance the locality of instruction references. This can be achieved by careful partitioning of a dataflow program into vertical layers of data dependent instructions, and proper distribution and allocation of the recurrence portions of the dataflow program. Enhancing the locality of data references in flow architecture is a more challenging problem. This paper studies the design of instruction, data (operand) and I-Structure cache memories. The performance results obtained using various benchmark programs are presented and analyzed.

The role of cache memories and the factors that decide the success of a particular design are examined. The operation of a cache memory is described. The specification of cache parameters is considered. Also discussed are the size of a cache, cache hierarchies, fetching and replacing, cache organization, updating the main memory, the use of two caches rather than one, virtual-address caches, and cache consistency.

Recently, energy dissipation in microprocessors is getting larger, which leads to a serious problem in terms of allowable temperature and performance improvement for future microprocessors. Cache memory is effective in bridging a growing speed gap between a processor and relatively slow external main memory, and has increased in its size. However, energy dissipation in the cache memory will approach or exceed 50% of the increasing total energy dissipation in processors. An important point to note is that, in the near future, static (leakage) energy will dominate the total energy consumption in deep sub-micron processes. This paper describes a code-generation technique that utilizes special instructions for energy reduction. The instructions perform self-invalidation in cache memories, which leads to efficient energy reduction. We developed a source-to-source-code compiler that implements the automatic code-generation. The simulation results of the generated codes show that our techniques can reduce a substantial amount of leakage energy without large performance degradation.

Two proposals for the inclusion of directory information in the last-level private caches of glueless shared-memory multiprocessors

Random Access Memory plays a crucial role in data processing in various computing systems for faster applications. A processor always fetches the data from the main memory for processing, sometimes the same data may be required for the processing and need to be fetched repeatedly from the main memory results time consuming. Cache memory supports faster data storage and access by storing instances of programs and data which is routinely accessed by the processor. Therefore, the cache memory is used to store recently fetched data and when a processor requests to fetch the data the controller will first check the data in cache, if the fetched data is there in the cache then it will be fetched otherwise the controller will fetch the data from the main memory. Therefore, the cache memory is useful for improving speed of processing without wasting much time for fetching the repeated data. This paper deals with various structures of single ended S-RAM cells and proposes a novel three transistor S -RAM cell design Using Tanner 45nm Technology.

Embedded systems, mainly battery-powered, must guarantee low power consumption and good performance. The cache memory design is crucial in embedded systems. Given the high number of parameters and their ranges of values, the exhaustive exploration of resulting solution space is an unaffordable task.

Nonvolatile random access memory (NVRAM) is becoming a popular alternative as the memory and storage medium in battery-powered embedded systems because of its fast read/write performance, byte-addressability, and nonvolatility. A well-known example is phase-change memory (PCM) that has much longer life expectancy and faster access performance than NAND flash. When NVRAM is considered as both main memory and storage in battery-powered embedded systems, existing page cache mechanisms have too many unnecessary data movements between main memory and storage. To tackle this issue, we propose the concept of “union page cache,” to jointly manage data of the page cache in both main memory and storage. To realize this concept, we design a partial page cache strategy that considers both main memory and storage as its management space. This strategy can eliminate unnecessary data movements between main memory and storage without sacrificing the data integrity of file systems. A series of experiments was conducted on an embedded platform. The results show that the proposed strategy can improve the file accessing performance up to 85.62% when PCM used as a case study.

Main memory contains transient information for all resident applications. However, if memory chip contents survives power-off, e.g., via freezing DRAM chips, sensitive data such as passwords and keys can be extracted. Main memory persistence will soon be the norm as recent advancements in MRAM and FeRAM position non-volatile memory technologies for widespread deployment in laptop, desktop, and embedded system main memory. Unfortunately, the same properties that provide energy efficiency, tolerance against power failure, and instant-on'' power-up also subject systems to offline memory scanning. In this paper, we propose a memory encryption control unit (MECU) that provides memory confidentiality during system suspend and across reboots. The MECU encrypts all memory transfers between the processor-local level 2 cache and main memory to ensure plaintext data is never written to the persistent medium. The MECU design is outlined and performance and security trade-offs considered. We evaluate a MECU-enhanced architecture using the SimpleScalar hardware simulation framework on several hardware benchmarks. This analysis shows the majority of memory accesses are delayed by less than 1 ns, with higher access latencies (caused by resume state reconstruction) subsiding within 0.25 seconds of a system resume. In effect, the MECU provides zero-cost steady state memory confidentiality for non-volatile main memory.

Cache memory hierarchies are used to buffer those portions of main memory with the most frequent use by the CPU. As cache memory is very costly, good design techniques must consider small cache sizes maintaining high levels of use (hit ratio) and ease of implementation. The memory replacement policy is important in maintaining a high hit ratio. Most replacement policies used are easily implemented when the main memory has fixed page locations. A new cache algorithm using a variable page configuration is explained in terms of program behaviour.

Global load instruction aggregation based on dimensions of arrays