Cache pollution

About: Cache pollution is a research topic. Over the lifetime, 11353 publications have been published within this topic receiving 262139 citations.

System and Method for dynamically controlling cache management

Abstract: A cache management system and method monitors and controls the contents of cache memory (12) coupled to at least one host (22a) and at least one data storage device (18a). A cache indexer (16) maintains a current index (25) of data elements which are stored in cache memory (12). A sequential data access indicator (30), responsive to the cache index (16) and to a user selectable sequential data access threshold, determines that a sequential data access is in progress for a given process and provides an indication of the same. The system and method allocate a micro-cache memory (12) to any process performing a sequential data access. In response to the indication of a sequential data access in progress and to a user selectable maximum number of data elements to be prefetched, a data retrieval requestor requests retrieval of up to the selected maximum number of data elements from a data storage device (18b). A user selectable number of sequential data elements determines when previously used micro-cache memory locations will be overwritten. A method of dynamically monitoring and adjusting cache management parameters is also disclosed.

System and method for bandwidth optimization in a network storage environment

Abstract: According to one or more embodiments of the present invention, a network cache intercepts data requested by a client from a remote server interconnected with the cache through one or more wide area network (WAN) links (e.g., for Wide Area File Services, or “WAFS”). The network cache stores the data and sends the data to the client. The cache may then intercept a first write request for the data from the client to the remote server, and determine one or more portions of the data in the write request that changed from the data stored at the cache (e.g., according to one or more hashes created based on the data). The network cache then sends a second write request for only the changed portions of the data to the remote server.

Scheduling threads for constructive cache sharing on CMPs

Abstract: In chip multiprocessors (CMPs), limiting the number of offchip cache misses is crucial for good performance. Many multithreaded programs provide opportunities for constructive cache sharing, in which concurrently scheduled threads share a largely overlapping working set. In this paper, we compare the performance of two state-of-the-art schedulers proposed for fine-grained multithreaded programs: Parallel Depth First (PDF), which is specifically designed for constructive cache sharing, and Work Stealing (WS), which is a more traditional design. Our experimental results indicate that PDF scheduling yields a 1.3--1.6X performance improvement relative to WS for several fine-grain parallel benchmarks on projected future CMP configurations; we also report several issues that may limit the advantage of PDF in certain applications. These results also indicate that PDF more effectively utilizes off-chip bandwidth, making it possible to trade-off on-chip cache for a larger number of cores. Moreover, we find that task granularity plays a key role in cache performance. Therefore, we present an automatic approach for selecting effective grain sizes, based on a new working set profiling algorithm that is an order of magnitude faster than previous approaches. This is the first paper demonstrating the effectiveness of PDF on real benchmarks, providing a direct comparison between PDF and WS, revealing the limiting factors for PDF in practice, and presenting an approach for overcoming these factors.

Exploiting spatial locality in data caches using spatial footprints

Abstract: Modern cache designs exploit spatial locality by fetching large blocks of data called cache lines on a cache miss. Subsequent references to words within the same cache line result in cache hits. Although this approach benefits from spatial locality, less than half of the data brought into the cache gets used before eviction. The unused portion of the cache line negatively impacts performance by wasting bandwidth and polluting the cache by replacing potentially useful data that would otherwise remain in the cache.This paper describes an alternative approach to exploit spatial locality available in data caches. On a cache miss, our mechanism, called Spatial Footprint Predictor (SFP), predicts which portions of a cache block will get used before getting evicted. The high accuracy of the predictor allows us to exploit spatial locality exhibited in larger blocks of data yielding better miss ratios without significantly impacting the memory access latencies. Our evaluation of this mechanism shows that the miss rate of the cache is improved, on average, by 18% in addition to a significant reduction in the bandwidth requirement.

Managing cache coherency in a data processing apparatus

Abstract: Each of plural processing units has a cache, and each cache has indication circuitry containing segment filtering data. The indication circuitry responds to an address specified by an access request from an associated processing unit to reference the segment filtering data to indicate whether the data is either definitely not stored or is potentially stored in that segment. Cache coherency circuitry ensures that data accessed by each processing unit is up-to-date and has snoop indication circuitry whose content is derived from the already-provided segment filtering data. For certain access requests, the cache coherency circuitry initiates a coherency operation during which the snoop indication circuitry determines whether any of the caches requires a snoop operation. For each cache that does, the cache coherency circuitry issues a notification to that cache identifying the snoop operation to be performed.