Smart Cache

About: Smart Cache is a research topic. Over the lifetime, 7680 publications have been published within this topic receiving 180618 citations.

Data cache locking for higher program predictability

Abstract: Caches have become increasingly important with the widening gap between main memory and processor speeds. However, they are a source of unpredictability due to their characteristics, resulting in programs behaving in a different way than expected.Cache locking mechanisms adapt caches to the needs of real-time systems. Locking the cache is a solution that trades performance for predictability: at a cost of generally lower performance, the time of accessing the memory becomes predictable.This paper combines compile-time cache analysis with data cache locking to estimate the worst-case memory performance (WCMP) in a safe, tight and fast way. In order to get predictable cache behavior, we first lock the cache for those parts of the code where the static analysis fails. To minimize the performance degradation, our method loads the cache, if necessary, with data likely to be accessed.Experimental results show that this scheme is fully predictable, without compromising the performance of the transformed program. When compared to an algorithm that assumes compulsory misses when the state of the cache is unknown, our approach eliminates all overestimation for the set of benchmarks, giving an exact WCMP of the transformed program without any significant decrease in performance.

Online coded caching

Abstract: We consider a basic content distribution scenario consisting of a single origin server connected through a shared bottleneck link to a number of users each equipped with a cache of finite memory. The users issue a sequence of content requests from a set of popular files, and the goal is to operate the caches as well as the server such that these requests are satisfied with the minimum number of bits sent over the shared link. Assuming a basic Markov model for renewing the set of popular files, we characterize approximately the optimal long-term average rate of the shared link. We further prove that the optimal online scheme has approximately the same performance as the optimal offline scheme, in which the cache contents can be updated based on the entire set of popular files before each new request. To support these theoretical results, we propose an online coded caching scheme termed coded least-recently sent (LRS) and simulate it for a demand time series derived from the dataset made available by Netflix for the Netflix Prize. For this time series, we show that the proposed coded LRS algorithm significantly outperforms the popular least-recently used (LRU) caching algorithm.

Methods and apparatus for implementing a pseudo-LRU cache memory replacement scheme with a locking feature

Abstract: In a memory system having a main memory and a faster cache memory, a cache memory replacement scheme with a locking feature is provided. Locking bits associated with each line in the cache are supplied in the tag table. These locking bits are preferably set and reset by the application program/process executing and are utilized in conjunction with cache replacement bits by the cache controller to determine the lines in the cache to replace. The lock bits and replacement bits for a cache line are "ORed" to create a composite bit for the cache line. If the composite bit is set the cache line is not removed from the cache. When deadlock due to all composite bits being set will result, all replacement bits are cleared. One cache line is always maintained as non-lockable. The locking bits "lock" the line of data in the cache until such time when the process resets the lock bit. By providing that the process controls the state of the lock bits, the intelligence and knowledge the process contains regarding the frequency of use of certain memory locations can be utilized to provide a more efficient cache.

An Adaptive Shared/Private NUCA Cache Partitioning Scheme for Chip Multiprocessors

Abstract: The significant speed-gap between processor and memory and the limited chip memory bandwidth make last-level cache performance crucial for future chip multiprocessors. To use the capacity of shared last-level caches efficiently and to allow for a short access time, proposed non-uniform cache architectures (NUCAs) are organized into per-core partitions. If a core runs out of cache space, blocks are typically relocated to nearby partitions, thus managing the cache as a shared cache. This uncontrolled sharing of all resources may unfortunately result in pollution that degrades performance. We propose a novel non-uniform cache architecture in which the amount of cache space that can be shared among the cores is controlled dynamically. The adaptive scheme estimates, continuously, the effect of increasing/decreasing the shared partition size on the overall performance. We show that our scheme outperforms a private and shared cache organization as well as a hybrid NUCA organization in which blocks in a local partition can spill over to neighbor core partitions

Protocol for distributing fresh content among networked cache servers

Abstract: A technique for automatic, transparent, distributed, scalable and robust replication of document copies in a computer network wherein request messages for a particular document follow paths from the clients to a home server that form a routing graph. Client request messages are routed up the graph towards the home server as would normally occur in the absence of caching. However, cache servers are located along the route, and may intercept requests if they can be serviced. In order to be able to service requests in this manner without departing from standard network protocols, the cache server needs to be able to insert a packet filter into the router associated with it, and needs also to proxy for the home server from the perspective of the client. Cache servers cooperate to update cache content by communicating with neighboring caches whenever information is received about invalid cache copies.