673 results about "Cache hit rate" patented technology

Computer systems are typically designed with multiple levels of memory hierarchy. Prefetching has been employed to overcome the latency of fetching data or instructions from or to memory. Prefetching works well for data structures with regular memory access patterns, but less so for data structures such as trees, hash tables, and other structures in which the datum that will be used is not known a priori. The present invention significantly increases the cache hit rates of many important data structure traversals, and thereby the potential throughput of the computer system and application in which it is employed. The invention is applicable to those data structure accesses in which the traversal path is dynamically determined. The invention does this by aggregating traversal requests and then pipelining the traversal of aggregated requests on the data structure. Once enough traversal requests have been accumulated so that most of the memory latency can be hidden by prefetching the accumulated requests, the data structure is traversed by performing software pipelining on some or all of the accumulated requests. As requests are completed and retired from the set of requests that are being traversed, additional accumulated requests are added to that set. This process is repeated until either an upper threshold of processed requests or a lower threshold of residual accumulated requests has been reached. At that point, the traversal results may be processed.

Data access operations in a database system may be accelerated by allowing the memory cache to be supplemented with a disk cache. The disk cache can store data that isn't able to fit in the memory cache and, since it doesn't contain the primary copy of the data for the database, may organize the data in such a way that the data is able to be streamed from the disks in response to data read operations. The reduced number of read data operations allows the data to be read from the disk cache faster than it could be served from the primary storage facilities, which might not allow the data to be organized in the same manner. The cache hit ratio may be increased by compressing data prior to storing it in the cache. Additionally, where a particular portion of data stored on the disk cache is being used heavily, that portion may be pulled into memory cache to accelerate access to that portion of data.

The present invention is directed towards a method and system for providing a technique referred to as flash caching to respond to requests for an object, such as a dynamically generated object, from multiple clients. This technique of the present invention uses a dynamically generated object stored in a buffer for transmission to a client, for example in response to a request from the client, to also respond to additional requests for the dynamically generated object from other clients while the object is stored in the buffer. Using this technique, the present invention is able to increase cache hit rates for extremely fast changing dynamically generated objects that may not otherwise be cacheable.

A memory module includes a memory hub coupled to several memory devices. The memory hub includes at least one performance counter that tracks one or more system metrics—for example, page hit rate, prefetch hits, and/or cache hit rate. The performance counter communicates with a memory sequencer that adjusts its operation based on the system metrics tracked by the performance counter.

Computer systems are typically designed with multiple levels of memory hierarchy. Prefetching has been employed to overcome the latency of fetching data or instructions from or to memory. Prefetching works well for data structures with regular memory access patterns, but less so for data structures such as trees, hash tables, and other structures in which the datum that will be used is not known a priori. In modern transaction processing systems, database servers, operating systems, and other commercial and engineering applications, information is frequently organized in trees, graphs, and linked lists. Lack of spatial locality results in a high probability that a miss will be incurred at each cache in the memory hierarchy. Each cache miss causes the processor to stall while the referenced value is fetched from lower levels of the memory hierarchy. Because this is likely to be the case for a significant fraction of the nodes traversed in the data structure, processor utilization suffers. The inability to compute the address of the next address to be referenced makes prefetching difficult in such applications. The invention allows compilers and/or programmers to restructure data structures and traversals so that pointers are dereferenced in a pipelined manner, thereby making it possible to schedule prefetch operations in a consistent fashion. The present invention significantly increases the cache hit rates of many important data structure traversals, and thereby the potential throughput of the computer system and application in which it is employed. For data structure traversals in which the traversal path may be predetermined, a transformation is performed on the data structure that permits references to nodes that will be traversed in the future be computed sufficiently far in advance to prefetch the data into cache.

A memory module includes a memory hub coupled to several memory devices. The memory hub includes at least one performance counter that tracks one or more system metrics-for example, page hit rate, number or percentage of prefetch hits, cache hit rate or percentage, read rate, number of read requests, write rate, number of write requests, rate or percentage of memory bus utilization, local hub request rate or number, and/or remote hub request rate or number.

Disclosed embodiments are directed to systems and methods for dynamic overprovisioning for data storage systems. In one embodiment, a data storage system can reserve a portion of memory, such as non-volatile solid-state memory, for overprovisioning. Depending on various overprovisioning factors, recovered storage space due to compressing user data can be allocated for storing user data and/or overprovisioning. Utilizing the disclosed dynamic overprovisioning systems and methods can result is more efficient utilization of cache memory, reduction of write amplification, increase in a cache hit rate, and the like. Improved data storage system performance and increased endurance and longevity can thereby be attained.

Techniques to improve query caching performance by efficiently selecting queries stored in a cache for evaluation and increasing the cache hit rate by allowing for inexact matches. A list of candidate queries stored in the cache that potentially could be used to answer a new query is first determined. This list may include all cached queries, cached queries containing exact matches for select list items, or cached queries containing exact and/or inexact matches. Each of at least one candidate query is then evaluated to determine whether or not there is a cache hit, which indicates that the candidate query could be used to answer the new query. The evaluation is performed using a set of rules that allows for inexact matches of aggregates, if any, in the new query. A query plan is generated for the new query based on a specific candidate query with a cache hit.

Determining a cache hit ratio of a caching device analytically and precisely. There is provided a cache hit ratio estimating apparatus for estimating the cache hit ratio of a caching device, caching access target data accessed by a requesting device, including: an access request arrival frequency obtaining section for obtaining an average arrival frequency measured for access requests for each of the access target data; an access request arrival probability density function generating section for generating an access request arrival probability density function which is a probability density function of arrival time intervals of access requests for each of the access target data on the basis of the average arrival frequency of access requests for the access target data; and a cache hit ratio estimation function generating section for generating an estimation function for the cache hit ratio for each of the access target data on the basis of the access request arrival probability density function for the plurality of the access target data.

According to at least one embodiment, a method comprises receiving a session trace log identifying a plurality of sessions accessing streaming media files from a media server. The method further comprises deriving from the session trace log a segment trace log that identifies for each of a plurality of time intervals the segments of the streaming media files accessed, and using the segment trace log to develop an analytical cache performance model. According to at least one embodiment, a method comprises receiving workload information representing client accesses of streaming media files from a media server, and using an analytical cache performance model to compute a cache hit ratio for the media server under the received workload.

A method and apparatus for improving the system response time when URL filtering is employed to provide security for web access. The method involves gathering the attributes of the user, and pre-populating a local URL-rating cache with URLs and corresponding ratings associated with analogous attributes from a URL cache database. Thus, the cache hit rate is higher with a pre-populated local URL rating cache, and the system response time is also improved.

The invention discloses a cooperative caching method based on popularity prediction in a named data networking. When storing a content in the named data networking (NDN), the application of a strategy of caching at multiple parts along a path or a strategy of caching at important nodes causes high redundancy of node data and low utilization rate of a caching space in the networking. The method provided by the invention uses a 'partial cooperative caching mode', firstly, the content is subjected to future popularity prediction, then, the caching space of an optimal proportion is segmented from each node to be used as a local caching space for storing the content of high popularity. The rest part of each node stores the content of relatively low popularity through a neighborhood cooperation mode. An optimal space division proportion is calculated through considering hop count of an interest packet in node kit and server side request hit in the networking. Compared with the conventional caching strategy, the method provided by the invention increases the utilization rate of the caching space in the networking, reduces caching redundancy in the networking, improves a caching hit rate of the nodes in the networking, and promotes performance of the whole networking.

A system and method for dynamically selecting the data fetch path for improving the performance of the system improves data access latency by dynamically adjusting data fetch paths based on application data fetch characteristics. The application data fetch characteristics are determined through the use of a hit/miss tracker. It reduces data access latency for applications that have a low data reuse rate (streaming audio, video, multimedia, games, etc.) which will improve overall application performance. It is dynamic in a sense that at any point in time when the cache hit rate becomes reasonable (defined parameter), the normal cache lookup operations will resume. The system utilizes a hit/miss tracker which tracks the hits/misses against a cache and, if the miss rate surpasses a prespecified rate or matches an application profile, the hit/miss tracker causes the cache to be bypassed and the data is pulled from main memory or another cache thereby improving overall application performance.

The invention discloses a memory caching method oriented to range querying on Hadoop. The memory caching method oriented to the range querying on the Hadoop comprises the following steps that (1) an index is established on querying attributes of Hadoop mass data and is stored on an Hbase; (2) a memory is established on index data of the Hbase to conduct fragment caching, the frequently-accessed index data are selected and stored in the memory, data fragments are fragmented in an initial stage by adopting a fixed length equal dividing method, and the mass data fragments are organized by adopting a skiplist; (3) hit data are queried and recorded according to the data, and the heat of the data fragments is measured by adopting an exponential smoothing method; (4) a memory cache is updated. The memory caching method oriented to the range querying on the Hadoop has the advantages that the structure of combining the skiplist and a collection is adopted, the dynamic adjustment of the fragment boundary of the collection is supported on the structure, the data fragments are made to be adaptive to querying demands, the querying cache hit rate of hot data fragments is improved, the overhead of a querying accessed disk is lowered, and thus the performance of the range querying is improved greatly.

The invention discloses a method for balancing a load of a network GIS (Geographic Information System) heterogeneous cluster server. In the method, built-in attributes which accord with the Zipf distribution rule and a server heterogeneous processing capacity are accessed on the basis of GIS data; the method adapts to dense access of a user in the aspect of the cluster caching distribution; when the cache hit rate is improved, the access load of hot spot data is balanced; the minimum processing cost of a cluster system, which is required by a data request service, is solved from the integral performance of a heterogeneous cluster service system, and user access response time is optimized when the load of the heterogeneous cluster server is balanced; and the distribution processing is carried out on the basis of data request contents and the access load of the hot spot data is prevented from being excessively centralized. The method disclosed by the invention highly accords with the large-scale user highly-clustered access characteristic in a network GIS, well coordinates and balances the relation between the load distribution and the access local control, ensures the service efficiency and the optimization of the load, effectively promotes the service performance of the actual network GIS and the utilization efficiency of the heterogeneous cluster service system.

A circuit arrangement, program product and circuit arrangement utilize a textured bounding volume to reduce the overhead associated with generating and using an Accelerated Data Structure (ADS) in connection with physical rendering. In particular, a subset of the primitives in a scene may be mapped to surfaces of a bounding volume to generate textures on such surfaces that can be used during physical rendering. By doing so, the primitives that are mapped to the bounding volume surfaces may be omitted from the ADS to reduce the processing overhead associated with both generating the ADS and using the ADS during physical rendering, and furthermore, in many instances the size of the ADS may be reduced, thus reducing the memory footprint of the ADS, and often improving cache hit rates and reducing memory bandwidth.

The invention provides a data query method and a data query device, which can dynamically analyze hot queries, improve the cache hit rate and reduce the delay of query response by adopting a mode of coexistence of a first-level cache and a second-level cache, and can improve the accuracy of cached data by utilizing a data updating form of combination of an active cache and a passive cache. The method comprises the following steps: querying data from a first-level cache according to a received query request, and returning the data if the data is queried; Otherwise, continuing to call the external query service interface to perform data query; if the query is not overtime, returning the queried data; updating the inquired data into a first-level cache and a second-level cache; and if the query is overtime, querying data from a second-level cache and returning the data, the first-level cache having a first preset data expiration deletion time, the second-level cache having a second presetdata expiration deletion time, and the first preset data expiration deletion time being less than the second preset data expiration deletion time.

The present invention is directed towards a method and system for modifying by a cache responses from a server that do not identify a dynamically generated object as cacheable to identify the dynamically generated object to a client as cacheable in the response. In some embodiments, such as an embodiment handling HTTP requests and responses for objects, the techniques of the present invention insert an entity tag, or “etag” into the response to provide cache control for objects provided without entity tags and/or cache control information from an originating server. This technique of the present invention provides an increase in cache hit rates by inserting information, such as entity tag and cache control information for an object, in a response to a client to enable the cache to check for a hit in a subsequent request.

The invention discloses an edge caching system and method based on content popularity prediction. The method comprises the following steps that: (1) according to the historical request information ofa user, training the preference model of each user in a node coverage region offline; (2) when a request arrives, if requested contents are not in the presence in a cache region, on the basis of the preference model of the user, carrying out the on-line prediction of content popularity; (3) comparing a content popularity prediction value with the minimum value of the content popularity of the cache region, and making a corresponding caching decision; and (4) updating a content popularity value at a current moment, evaluating the preference model of the user, and determining whether the offlinelearning of the preference model of the user is started or not. By use of the method, an edge node can predict the content popularity online and track the change of the content popularity in real time, the corresponding caching decision is made on the basis of the predicted content popularity, so that the edge node is guaranteed to continuously cache hot contents, and a caching hit rate which approaches to an ideal caching method is obtained.

The mobile VOD business system with super performance based on GPRS mobile network comprises: besides traditional net element, a CCCP server on boundary of GGSN and PDN to release load for SCS and reduce bandwidth consumption between GGSN and SGS, a UECP server arranged in BSS that is between BSC and BTS to self-adaptive improve buffer hit rate based on buffer alternative strategy and ensure fast response to most user request, and a high-speed IP DL between CCP and UECP to transmit flow media content and construct two-stage buffer device with two proxy servers to bypass great media and reduce data flux and load for other link and eliminate the effect of VOD to network performance.