Improving direct-mapped cache performance by the addition of a small fully-associative cache and prefetch buffers
01 May 1990-Vol. 18, pp 364-373
TL;DR: In this article, a hardware technique to improve the performance of caches is presented, where a small fully-associative cache between a cache and its refill path is used to place prefetched data and not in the cache.
Abstract: Projections of computer technology forecast processors with peak performance of 1,000 MIPS in the relatively near future. These processors could easily lose half or more of their performance in the memory hierarchy if the hierarchy design is based on conventional caching techniques. This paper presents hardware techniques to improve the performance of caches.Miss caching places a small fully-associative cache between a cache and its refill path. Misses in the cache that hit in the miss cache have only a one cycle miss penalty, as opposed to a many cycle miss penalty without the miss cache. Small miss caches of 2 to 5 entries are shown to be very effective in removing mapping conflict misses in first-level direct-mapped caches.Victim caching is an improvement to miss caching that loads the small fully-associative cache with the victim of a miss and not the requested line. Small victim caches of 1 to 5 entries are even more effective at removing conflict misses than miss caching.Stream buffers prefetch cache lines starting at a cache miss address. The prefetched data is placed in the buffer and not in the cache. Stream buffers are useful in removing capacity and compulsory cache misses, as well as some instruction cache conflict misses. Stream buffers are more effective than previously investigated prefetch techniques at using the next slower level in the memory hierarchy when it is pipelined. An extension to the basic stream buffer, called multi-way stream buffers, is introduced. Multi-way stream buffers are useful for prefetching along multiple intertwined data reference streams.Together, victim caches and stream buffers reduce the miss rate of the first level in the cache hierarchy by a factor of two to three on a set of six large benchmarks.
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02 Jun 1997
21 citations
30 Sep 2007
TL;DR: Novel schemes to manage the translated code buffer used by DBT with scratchpad memory using footprint reduction, victim compression, and fragment pinning to avoid evicting needed code are proposed.
Abstract: Dynamic binary translation (DBT) has been used to achieve numerous goals (e.g., better performance) for general-purpose computers. Recently, DBT has also attracted attention for embedded systems. However, a challenge to DBT in this domain is stringent constraints on memory and performance. The translated code buffer used by DBT may occupy too much memory space. This paper proposes novel schemes to manage this buffer with scratchpad memory. We use footprint reduction to minimize the space needed by the translated code, victim compression to reduce the cost of retranslating previously seen code, and fragment pinning to avoid evicting needed code. We comprehensively evaluate our techniques to demonstrate their effectiveness.
20 citations
01 Jan 2004
TL;DR: The behavior of the memory hierarchy is key to high performance in today's GHz microprocessors as mentioned in this paper, and the cache level closest to the processor is limited in size and associativity in order to match the short cycle time of the CPU.
Abstract: The behavior of the memory hierarchy is key to high performance in today’s GHz microprocessors. The cache level closest to the processor is limited in size and associativity in order to match the short cycle time of the CPU. Even though only data objects soon reused again will benefit from the small cache, all accessed data objects are normally allocated in the cache.
20 citations
Patent•
12 Jul 1996TL;DR: In this article, the local memory in each node of shared memory is utilized as a backing store for blocks discarded from the processor cache to delay the address binding to local memory until the blocks are discarded from processor cache.
Abstract: A data processing apparatus having a memory access architecture which utilizes distributed shared-memory multiprocessors, and relates more particularly to a non-inclusive memory access mechanism in said architecture. The local memory in each node of shared memory is utilized as a backing store for blocks discarded from the processor cache to delay the address binding to the local memory until the blocks are discarded from the processor cache. Such avoids enforcement of the inclusion property and long latency due to the inclusion property. The invention further provides a method of maintaining coherency in a system which utilizes a distributed shared-memory multiprocessors architecture.
20 citations
Patent•
10 Dec 1999TL;DR: In this article, a client is given control over the pre-fetching of resources by identifying property values that are intrinsically tied to the contents of the resources and determining whether resources are already resident within the cache.
Abstract: A client is given control over the pre-fetching of resources. The client may be, for example, resident on an electronic device such as a computer system that caches resources. The resources may be, for instance, web pages. Identifying property values that are intrinsically tied to the contents of the resources are used to determine whether resources are already resident within the cache prior to pre-fetching the resources. In addition, the client may request information regarding a resource to assist the client in determining whether to pre-fetch the resource. Such information may include the size of the resource and other information.
20 citations
References
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TL;DR: Specific aspects of cache memories investigated include: the cache fetch algorithm (demand versus prefetch), the placement and replacement algorithms, line size, store-through versus copy-back updating of main memory, cold-start versus warm-start miss ratios, mulhcache consistency, the effect of input /output through the cache, the behavior of split data/instruction caches, and cache size.
Abstract: design issues. Specific aspects of cache memories tha t are investigated include: the cache fetch algorithm (demand versus prefetch), the placement and replacement algorithms, line size, store-through versus copy-back updating of main memory, cold-start versus warm-start miss ratios, mulhcache consistency, the effect of input /output through the cache, the behavior of split data/instruction caches, and cache size. Our discussion includes other aspects of memory system architecture, including translation lookaside buffers. Throughout the paper, we use as examples the implementation of the cache in the Amdahl 470V/6 and 470V/7, the IBM 3081, 3033, and 370/168, and the DEC VAX 11/780. An extensive bibliography is provided.
1,614 citations
01 Jan 1990
TL;DR: This note evaluates several hardware platforms and operating systems using a set of benchmarks that test memory bandwidth and various operating system features such as kernel entry/exit and file systems to conclude that operating system performance does not seem to be improving at the same rate as the base speed of the underlying hardware.
Abstract: This note evaluates several hardware platforms and operating systems using a set of benchmarks that test memory bandwidth and various operating system features such as kernel entry/exit and file systems. The overall conclusion is that operating system performance does not seem to be improving at the same rate as the base speed of the underlying hardware. Copyright 1989 Digital Equipment Corporation d i g i t a l Western Research Laboratory 100 Hamilton Avenue Palo Alto, California 94301 USA
467 citations
01 Apr 1989
TL;DR: A parameterizable code reorganization and simulation system was developed and used to measure instruction-level parallelism and the average degree of superpipelining metric is introduced, suggesting that this metric is already high for many machines.
Abstract: Superscalar machines can issue several instructions per cycle. Superpipelined machines can issue only one instruction per cycle, but they have cycle times shorter than the latency of any functional unit. In this paper these two techniques are shown to be roughly equivalent ways of exploiting instruction-level parallelism. A parameterizable code reorganization and simulation system was developed and used to measure instruction-level parallelism for a series of benchmarks. Results of these simulations in the presence of various compiler optimizations are presented. The average degree of superpipelining metric is introduced. Our simulations suggest that this metric is already high for many machines. These machines already exploit all of the instruction-level parallelism available in many non-numeric applications, even without parallel instruction issue or higher degrees of pipelining.
316 citations
TL;DR: It is shown that prefetching all memory references in very fast computers can increase the effective CPU speed by 10 to 25 percent.
Abstract: Memory transfers due to a cache miss are costly. Prefetching all memory references in very fast computers can increase the effective CPU speed by 10 to 25 percent.
315 citations
17 May 1988
TL;DR: The inclusion property is essential in reducing the cache coherence complexity for multiprocessors with multilevel cache hierarchies and a new inclusion-coherence mechanism for two-level bus-based architectures is proposed.
Abstract: The inclusion property is essential in reducing the cache coherence complexity for multiprocessors with multilevel cache hierarchies. We give some necessary and sufficient conditions for imposing the inclusion property for fully- and set-associative caches which allow different block sizes at different levels of the hierarchy. Three multiprocessor structures with a two-level cache hierarchy (single cache extension, multiport second-level cache, bus-based) are examined. The feasibility of imposing the inclusion property in these structures is discussed. This leads us to propose a new inclusion-coherence mechanism for two-level bus-based architectures.
236 citations