Reducing Load Latency in Multi-level Cache Hierarchy PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Reducing Load Latency in Multi-level Cache Hierarchy PDF full book. Access full book title Reducing Load Latency in Multi-level Cache Hierarchy by Majid Jalili. Download full books in PDF and EPUB format.
Author: Majid Jalili
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
High load latency that results from deep cache hierarchies and relatively slow main memory is an important limiter of single-thread performance. Despite decades of research, reducing load latency is still a top priority to achieve high performance. Data prefetch helps reduce this latency by fetching data up the hierarchy before it is requested by load instructions. However, data prefetching has shown to be lacking in many situations. I make three observations about modern processors relevant to load latency: (1) the cache hierarchy is getting deeper (L4 is being added) and larger in size, requiring new mechanisms to traverse the memory hierarchy without increasing load latency; (2) core counts are increasing and at the same time applications are exhibiting more complex and diverse access patterns, demanding more and better prefetchers to be adopted; and (3) overall processor utilization in cloud servers is very low (
Author: Majid Jalili
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
High load latency that results from deep cache hierarchies and relatively slow main memory is an important limiter of single-thread performance. Despite decades of research, reducing load latency is still a top priority to achieve high performance. Data prefetch helps reduce this latency by fetching data up the hierarchy before it is requested by load instructions. However, data prefetching has shown to be lacking in many situations. I make three observations about modern processors relevant to load latency: (1) the cache hierarchy is getting deeper (L4 is being added) and larger in size, requiring new mechanisms to traverse the memory hierarchy without increasing load latency; (2) core counts are increasing and at the same time applications are exhibiting more complex and diverse access patterns, demanding more and better prefetchers to be adopted; and (3) overall processor utilization in cloud servers is very low (
Author: Steven A. Przybylski
Publisher: Elsevier
ISBN: 0080500595
Category : Computers
Languages : en
Pages : 238
Get Book Here
Book Description
An authoritative book for hardware and software designers. Caches are by far the simplest and most effective mechanism for improving computer performance. This innovative book exposes the characteristics of performance-optimal single and multi-level cache hierarchies by approaching the cache design process through the novel perspective of minimizing execution times. It presents useful data on the relative performance of a wide spectrum of machines and offers empirical and analytical evaluations of the underlying phenomena. This book will help computer professionals appreciate the impact of caches and enable designers to maximize performance given particular implementation constraints.
Author: Rajeev Balasubramonian
Publisher: Springer Nature
ISBN: 303101734X
Category : Technology & Engineering
Languages : en
Pages : 137
Get Book Here
Book Description
A key determinant of overall system performance and power dissipation is the cache hierarchy since access to off-chip memory consumes many more cycles and energy than on-chip accesses. In addition, multi-core processors are expected to place ever higher bandwidth demands on the memory system. All these issues make it important to avoid off-chip memory access by improving the efficiency of the on-chip cache. Future multi-core processors will have many large cache banks connected by a network and shared by many cores. Hence, many important problems must be solved: cache resources must be allocated across many cores, data must be placed in cache banks that are near the accessing core, and the most important data must be identified for retention. Finally, difficulties in scaling existing technologies require adapting to and exploiting new technology constraints. The book attempts a synthesis of recent cache research that has focused on innovations for multi-core processors. It is an excellent starting point for early-stage graduate students, researchers, and practitioners who wish to understand the landscape of recent cache research. The book is suitable as a reference for advanced computer architecture classes as well as for experienced researchers and VLSI engineers. Table of Contents: Basic Elements of Large Cache Design / Organizing Data in CMP Last Level Caches / Policies Impacting Cache Hit Rates / Interconnection Networks within Large Caches / Technology / Concluding Remarks
Author: Jean-Loup Baer
Publisher: Cambridge University Press
ISBN: 0521769922
Category : Computers
Languages : en
Pages : 382
Get Book Here
Book Description
This book describes the architecture of microprocessors from simple in-order short pipeline designs to out-of-order superscalars.
Author: Nam L. Duong
Publisher:
ISBN: 9781303785801
Category :
Languages : en
Pages : 162
Get Book Here
Book Description
Designing an effective cache management policy for a multi-level cache hierarchy has been a hot research topic to bridge the gap between the fast microprocessor and the long memory latency. It is becoming critically important in modern microprocessors due to the emerge of new hardware architectures, new technologies and new applications. However, it has been shown that this is not an easy task due to the complexity of the inputs that computer architects must take into account. The bottom-up approach has been used in designing such a policy. Rather than tackling the problem with all the possible inputs, a management policy is broken down into smaller problems, each targeting a smaller number of inputs. Sub-policies, such as replacement, bypass, migration and partitioning, are studied for a specific event or configuration. Solutions have been proposed for these individual policies or their combinations. In either case, the new policies must be shown to work well with existing baseline policies. In this dissertation, using the bottom-up approach, we propose new management policies for a multi-level cache hierarchy. Using new ideas about an effective policy or improving existing methods for new hardware architectures, we further optimize the current state-of-the-art policies. Specifically, we propose three new sets of management policies. First, new migration policies are proposed for an L0/L1 cache hierarchy for embedded processors. We propose two new cache designs to enhance operations of the L1 caches. Second, we propose a new combined replacement, bypass and partitioning policy for a last-level cache by achieving the balance between cache reuse and pollution. The new policy is shown to reduce pollution due to keeping cache lines too long in the cache, a problem which was not addressed by prior work. And third, we propose a new coordinated bypass policy for a multi-level cache hierarchy using the new classifications of cache lines and their reuse probabilities. This policy works well with any existing policies and architectures which allow bypass. The new cache management policies are shown to improve existing policies or optimize the design with an acceptable performance loss. They are shown to work well with the baseline policies. We also present hardware architectures and application classes that each new policy will be applied to. Hardware design is also described and is shown to be feasible and have low overhead.
Author: Jesus Labarta
Publisher: Springer Science & Business Media
ISBN: 3540777032
Category : Computers
Languages : en
Pages : 536
Get Book Here
Book Description
This book constitutes the refereed joint post-conference proceedings of the 6th International Symposium on High-Performance Computing, ISHPC 2005, held in, Japan, in 2005. It also includes the refereed post-proceedings of the First International Workshop on Advanced Low Power Systems 2006, ALPS2006, and some from the Workshop on Applications for PetaFLOPS Computing, APC 2005. A total of 42 papers were carefully selected from 76 submissions, covering a huge range of topics.
Author: Jiajun Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 296
Get Book Here
Book Description
Memory subsystem with larger capacity and deeper hierarchy has been designed to achieve the maximum performance of data intensive workloads. What grows with the depth and capacity is the amount of data movement happened between different levels of caches and the associated energy consumption. Prior art [65] shows that the energy cost of moving data from memory to register is two orders higher than the cost of register-to-register double-precision floating point operations. As the cache hierarchy grows deeper, the energy cost on the large amount of data movement between cache layers has become non-negligible. Energy dissipation of future systems will be dominated by the cost of data movement. Thus, reducing data movement through exploiting data locality becomes essential to build energy-efficient architectures. A promising technique to improve the energy efficiency of modern memory subsystem is to adaptively guide data placement into appropriate caches with the performance benefit and energy cost of data movement in mind. An intelligent data placement scheme should only move data blocks with future re-reference into cache. As the working set size of emerging workloads exceeds cache capacity and the number of cores and IPs sharing caches keeps increasing, a data movement aware data placement scheme can maximize the performance of cache-sensitive workloads and minimize the cache energy consumption of cache-insensitive workloads. Researchers have noticed that exclusive caches have better performance compared to inclusive caches. However, high performance improvement is always at odds with low energy consumption. The amount of data movement and energy consumption of exclusive caches is higher than inclusive ones. A few state-of-the-art CPU caching insertion/bypass policies have been proposed in literature. However these techniques are either at great expense of metadata overhead when adapting to exclusive caches, or they focus on reducing data movement at the sacrifice of performance. On the GPU side, designing efficient data placement schemes also faces great challenge. CPU caching schemes do not work for GPU memory subsystems, because the SRAM capacity per GPU thread is far smaller than the number per CPU threads. The capacity of GPU on-chip SRAMs is too small to hold large data structures in the GPU workloads. Data with frequent reuse is evicted before it is re-referenced which results in high GPU cache miss rate. Keeping the above shortcomings of prior work and key limitations in mind, this dissertation focuses on improving the performance and energy efficiency of modern cache subsystems of CPU and GPU by proposing performance and energy sensitive data placement schemes. This dissertation first presents a data placement for multilevel CPU caches to guide data placement into appropriate cache layers based on data reuse patterns. PC is utilized as the prediction heuristic based on the observation of good correlation between memory instruction and the locality of the data accessed by the instruction. Unlike prior art that includes great overhead for meta-data (e.g., PC) transmission and storage, a holistic approach to manage data placement is presented, which leverages bloom filters to record the memory instruction PC of data blocks. The proposed scheme incorporates quick detection and correction of stale/incorrect bypass decisions and an explicit mechanism for handling prefetches. This leads to energy efficiency improvement by cutting down wasteful cache block insertions and data movement. To overcome the challenges on the GPU side, an explicitly managed data placement scheme in GPU memory hierarchy is presented in this dissertation. In order to improve data reuse of a popular HPC application and eliminate redundant memory accesses, data access sequence is rearranged by fusing multiple GPU kernel execution. Bank level fine-grained on-chip SRAM data placement and replacement is designed based on the microarchitecture of GPU memory hierarchy to maximize capacity utilization and interconnect bandwidth. The proposed scheme achieves the best performance and least energy consumption through reducing memory access latency and eliminating redundant data movement
Author: Akanksha Jain
Publisher: Springer Nature
ISBN: 3031017625
Category : Technology & Engineering
Languages : en
Pages : 71
Get Book Here
Book Description
This book summarizes the landscape of cache replacement policies for CPU data caches. The emphasis is on algorithmic issues, so the authors start by defining a taxonomy that places previous policies into two broad categories, which they refer to as coarse-grained and fine-grained policies. Each of these categories is then divided into three subcategories that describe different approaches to solving the cache replacement problem, along with summaries of significant work in each category. Richer factors, including solutions that optimize for metrics beyond cache miss rates, that are tailored to multi-core settings, that consider interactions with prefetchers, and that consider new memory technologies, are then explored. The book concludes by discussing trends and challenges for future work. This book, which assumes that readers will have a basic understanding of computer architecture and caches, will be useful to academics and practitioners across the field.
Author: V. Carl Hamacher
Publisher: New York ; Toronto : McGraw-Hill
ISBN: 9780070256859
Category : Computers
Languages : en
Pages : 44
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 13
Get Book Here
Book Description
This paper provides quantitative measurements of load latency tolerance in a dynamically scheduled processor. To determine the latency tolerance of each memory load operation, our simulations use flexible load completion policies instead of a fixed memory hierarchy that dictates the latency. Although our policies delay load completion as long as possible, they produce performance (instructions committed per cycle (IPC)) comparable to an ideal memory system where all loads complete in one cycle. Our measurements reveal that to produce IPC values within 8% of the ideal memory system, between 1% and 62% of loads need to be satisfied within a single cycle and that up to 84% can be satisfied in as many as 32 cycles, depending on the benchmark and processor configuration. Load latency tolerance is largely determined by whether an unpredictable branch is in the load s data dependence graph and the depth of the dependence graph. Our results also show that up to 36% of all loads miss in the level one cache yet have latency demands lower than second level cache access times. We also show that up to 37% of loads hit in the level one cache even though they possess enough latency tolerance to be satisfied by lower levels of the memory hierarchy.
