Electrical computers and digital processing systems: memory – Storage accessing and control – Hierarchical memories
Reexamination Certificate
2001-05-25
2003-07-22
Yoo, Do Hyun (Department: 2187)
Electrical computers and digital processing systems: memory
Storage accessing and control
Hierarchical memories
C711S136000
Reexamination Certificate
active
06598125
ABSTRACT:
FIELD OF THE INVENTION
This technology relates generally to a method for caching information on the hard drive of a client computer. More particularly, the technology relates to a method for the caching of information between work sessions to increase the local accessibility of blocks of information.
BACKGROUND
Client computers are used to execute program software for many purposes. The software executed can comprises many different applications and types of content. Examples of content include any windows-based software, games, various applications, or any software that utilizes the file system of the client computer and employs session-base caching. Content can be executed on clients that utilize a variety of operating systems and hardware configurations. Content can be accessed many different times over the course of one or more work sessions.
A client computer requires blocks of information for the content to operate properly. The blocks of information can come from different data sources, such as a compact disk (CD), a DVD, or from another computer such as a file server. The client computer can be connected to the file server by a local network (LAN) or a wide area network (WAN), such as the Internet.
Generally, content must be installed on a client computer before it can be executed. It is generally installed from a data source, such as those listed above. During the installation process, files of a certain size that are frequently required for operation of the content are copied to the hard drive of the client computer. From there they are readily accessible. Since the hard drive of the client computer is generally limited in storage capacity, some of the large content files may not be copied to it. These large files could comprise, for example, video files, large executable files, or Dynamic Link Libraries. When they are needed these large content files must then be retrieved from the data source, which has a slower retrieval time. Alternatively, if only a portion of a large content file is to be used, the blocks of information representing this portion of the file can be cached on the hard drive of the client computer.
After installation, a work session can be started to commence use of the content. During the work session additional blocks of information are required. Some blocks of information are used more frequently than other blocks. The blocks of information can be obtained directly from the data source of the content if it is still available during the work session, although access times to this information are generally constrained. The slow response times are generally caused by the various technical and hardware limitations of the data source being used.
Conversely, the access time to blocks of information stored on the hard drive of a client computer is comparatively fast. However, the hard drive of a client computer may possess only limited storage capacity. For these reasons, the hard drive of the client computer is the preferred storage location for blocks of frequently accessed information that are of manageable size.
To reduce the impact of these limitations, various caching methods are used to optimize accessibility to the information required by the content of an active work session. A certain amount of storage space is set aside on the hard drive of the client computer for each content. As the content is used, blocks of information brought to the client compute from the data source are temporarily stored (cached) in this allocated space on the hard drive. As the space fills and new information needs to be stored, the oldest information is discarded to make room for the new. By this means faster repeated access can be provided to blocks of information that have been most recently used. Ultimately. When the work session using this content on the client computer is completed, the allocated space that was used on the hard drive is made available for use for other purposes. Unfortunately, the next time a work session is commenced for the same content, the blocks of information that had been cached are no longer available and need to be obtained again from the data source. This results in inefficiency and delays, and diminishes the overall experiences of the operator of the client computer.
What is needed is an improved method of caching blocks of information on a local client computer that reduces information transfer requirements from the data source, thereby improving the responsiveness of the client computer.
SUMMARY OF THE INVENTION
The present invention features a method for caching blocks of information on a client computer to address the preceding problems. In one aspect, the invention provides for the caching of blocks of information in an allocated storage space on the hard drive of a client computer. Access frequency information is stored for each block of information cached and is used to calculate a discard priority for the stored block. When an incoming block of information needs to be stored, storage space in the cache is made available for it by discarding blocks of information based on their calculated discard priority.
Another embodiment of the invention provides for the dynamic allocation of storage space on the computer between different caches. The dynamic allocation can reassign storage space from the cache of an inactive work session to that of an active work session or from the cache of an active work session to that of another active work session. The storage space to be reassigned is determined based upon block discard priority.
In another embodiment of the invention, the size of the allocated storage space for the work session can be changed. Reduction of the allocated storage space is performed by discarding blocks of information, based on their discard priority.
In yet another embodiment of the invention, the cached blocks of information are not discarded at the end of a work session, but are retained for use in a subsequent work session. In yet another embodiment, the access frequency information used to determine the discard priority of a block is determined using the number of times the block has been accessed in the present work session, in a prior work session, in a plurality of prior work sessions, or some combination. The discard priority determination can also be adjusted based on the amount of time since it has been most recently accessed.
Another aspect of the invention features a method for caching, blocks of information on the hard drive client computer employing, multiple work sessions. Storage space is allocated on a client computer for the cache of each cache. Access Blocks of information are the stored in the storage space of each. Access frequency information is stored for each block of information cached, and is used to calculated a discard priority for each stored block. When an incoming block of information needs to be stored, storage space is provided for the new block by discarding stored blocks of information from any of the active work sessions. The blocks to be discarded are determined based upon their calculated discard priority.
Another embodiment of the invention provides storage for the incoming block of information by discarding blocks of information from the cache of an inactive work session to that of an active work session, or from the cache of an active work session to that of another active work session. The storage space to be reassigned is determined based upon block discard priority.
In another embodiment of the invention, the cached blocks of information are not discarded at the end of a work session, but are retained for use in a subsequent work session. Another embodiment of the invention allows the size of the allocated storage space for a work session can be changed. Reduction of the allocated storage space is performed by discarding blocks of information, based on their discard priority.
In yet another embodiment, the access frequency information used to determine the discard priority of a block is determined using the number of times the block has been accessed in the present work
Exent Technologies, Ltd
Moazzami Nasser
Testa Hurwitz & Thibeault LLP
Yoo Do Hyun
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