Patent Application
20210334024
The present embodiment(s) relate to de-duplication of memory pages. More specifically, the embodiment(s) relate to employing transactional memory and parallelism to support and enable the de-duplication among elements.
A virtual machine is a software implementation of a physical machine, and exhibits the behavior of a separate computer. The virtual machine is a self-contained operating environment that behaves as if it is a separate computer, while allowing the sharing of underlying physical machine resources between multiple virtual machines. Each virtual machine operates as a whole machine, while a host of the virtual machine(s) manages resources to support each virtual machine. For example, a virtual machine consists of CPUs, memory, and I/O slots that are a subset of a pool of available resources within a computer system. Each of the virtual machines within the computer system is capable of running a version of an operating system and a set of application workloads. Regardless of the virtual machine category, the software running inside the virtual machine is limited to the resources and abstractions provided by the virtual machine.
The embodiments include a system, computer program product, and method for identifying memory de-duplication opportunities, and selectively subjecting memory pages to de-duplication.
In one aspect, a computer system is provided with a processing unit operatively coupled to memory and an operating system to support virtual memory page de-duplication. A de-duplication mechanism, operatively coupled to the processing unit, supports first and second de-duplication processes operatively coupled to first and second elements, with the processes configured to operate in parallel. The de-duplication mechanism, via one or more of the first and second de-duplication processes, is configured to identify a first memory page and selectively de-duplicate the first memory page. The functionality of the de-duplication mechanism includes: searching a first data structure for a first matching entry that represents a relatively identical memory page to the first memory page, and in response to such an identification representing the first memory page and the first matching entry in the first data structure; and searching the a second data structure for a second matching entry relatively identical to the first memory page in response to absence of the first matching entry in the first data structure. If the first memory page is not present, the first memory page is inserted in the second data structure, and if the first memory page is determined to be present, the first memory page is removed from the second data structure and represented with a corresponding matching entry in the first data structure. The de-duplication mechanism leverages transactional memory to resolve concurrent access of the first and second data structures.
In another aspect, a computer program product is provided to de-duplicate one or more memory pages. The computer program product is provided with a computer readable storage device having embodied program code. A de-duplication mechanism supports first and second de-duplication processes operatively coupled to first and second elements, respectively, with the processes configured to operate in parallel. Program code is configured to identify a first memory page and selectively de-duplicate the first memory page. The functionality of the de-duplication includes the program code to: search a first data structure for a first matching entry that represents a relatively identical memory page to the first memory page, and in response to such an identification represent the first memory page and the first matching entry in the first data structure; and search a second data structure for a second matching entry relatively identical to the first memory page in response to absence of the first matching entry in the first data structure. If the first memory page is not present, the program code inserts the first memory page in the second data structure, and if the first memory page is present, the program code removes the first memory page from the second data structure and represents the first memory page with a corresponding matching entry in the first data structure. The program code leverages transactional memory to resolve concurrent access of the first and second data structures.
In yet another aspect, a method is provided for de-duplicating one or more memory pages in a computer system configured with a de-duplication mechanism supporting first and second de-duplication processes operatively coupled to first and second elements, respectively, with the processes configured to operate in parallel. A first memory page is identified and subject to selective de-duplication. The functionality of the de-duplication includes: searching a first data structure for a first matching entry that represents a relatively identical memory page to the first memory page, and in response to such an identification representing the first memory page and the first matching entry in the first data structure; and searching a second data structure for a second matching entry relatively identical to the first memory page in response to absence of the first matching entry in the first data structure. If the first memory page is not present, the first memory page is inserted in the second data structure, and if the first memory page is present, the first memory page is removed from the second data structure and represented with a corresponding matching entry in the first data structure. Transactional memory is leveraged to resolve concurrent access of the first and second data structures.
These and other features and advantages will become apparent from the following detailed description of the presently preferred embodiment(s), taken in conjunction with the accompanying drawings.
The drawings reference herein forms a part of the specification. Features shown in the drawings are meant as illustrative of only some embodiments, and not of all embodiments, unless otherwise explicitly indicated.
It will be readily understood that the components of the present embodiments, as generally described and illustrated in the Figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following details description of the embodiments of the apparatus, system, method, and computer program product of the present embodiments, as presented in the Figures, is not intended to limit the scope of the embodiments, as claimed, but is merely representative of selected embodiments.
Reference throughout this specification to “a select embodiment,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiments. Thus, appearances of the phrases “a select embodiment,” “in one embodiment,” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment.
The illustrated embodiments will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the embodiments as claimed herein.
Referring to
A plurality of elements are shown operatively coupled to the host (110) via the host O/S (120), including element0 (1500), element1 (1501), and elementN (150N). Each element is a platform to run application and programs. For example, in an embodiment, one or more of the elements may be a virtual machine or a container. Although three elements are shown herein, the quantity should not be considered limiting. Each element is operatively coupled to a corresponding de-duplication process via the de-duplication mechanism (140). For example, element0 (1500) is operatively coupled to de-duplication process0 (1440), element1 (1501) is operatively coupled to de-duplication process1 (1441), and element (150N) is operatively coupled to de-duplication processN (144N).
A page of memory is a fixed number of bytes and represents a unit of data for memory management in a virtual memory operating system. Memory de-duplication is a technique which merges identical memory pages to save a physical memory resource. As shown herein, each element represented herein as element0 (1500), element1 (1501), and elementN (150N) is shown with a plurality of memory pages to support corresponding workloads. By way of example, element0 (1500) is shown with page0,0 (1600,0) and page0,1 (1600,1), element1 (1501) is shown with page1,0 (1601,0), and page1,1 (1601,1), and elementN (150N) is shown with pageN,0 (160N,0) and pageN,1 (160N,1). Although each element is shown with two pages, this quantity is not limiting. It is understood that there may be identical memory pages among the at least two elements due to similar workloads.
As shown and described herein, two or more de-duplication processes (1440), (1441), and (144N) are configured to run in parallel. Each de-duplication process (1440), (1441), and (144N) is responsible for scanning memory pages of an operatively coupled element. By way of example, de-duplication process0 (1440) is responsible for scanning pages (1600,0) and (1600,1) of element0 (1500), de-duplication process0 (1441) is responsible for scanning pages (1601,0) and (1601,1) of element1 (1501), and de-duplication processN (144N) is responsible for scanning pages (160N,0) and (160N,1) of elementN (150N). The de-duplication mechanism (140) functions to identify whether any page from one of the elements is identical to another page from either the same element or the other elements on the same physical machine, e.g. host (120). Memory pages are processed for de-duplication, and during this process they are subject to a comparison. However, in order to compare the pages or to compare the pages in an efficient manner, the comparison needs to evaluate similar objects. As shown and described herein, a hash function is leveraged to generate a hash code for the individual memory pages. Each of the de-duplication processes, e.g. (1440), (1441), and (144N), may individually leverage the hash function to generate a hash code for an individual memory page. It is understood in the art that a hash code is a numeric value, e.g. number, generated from any object. In this case, the hash code is generated for individual memory pages, and as described herein is used in identification of the memory pages during equality testing. Two objects are considered equal if they return equal hash codes. In the case of virtual machines or elements and corresponding virtual memory pages, two virtual memory pages are considered equal if they return equal hash codes. Accordingly, the hash function is used herein to map an individual virtual memory page to a fixed size value.
The values, e.g. hash codes, are used to represent the memory page(s). In an embodiment, a logical expression is utilized to compress or decrease the size of the generated hash code. When multiple de-duplication processes are running on the same physical machine, they need to collaborate with each other to detect identical pages among different elements (1500), (1501), . . . (150N). Concretely speaking, the de-duplication processes need to access two or more data structures in a shared manner. In an embodiment, the data structures are in the form of hash tables. The data structures are shared among the de-duplication processes to organize and manage memory pages for de-duplication. As shown and described herein, the data structures are referred to herein as a first data structure (170), e.g. first hash table or stable hash table, and a second data structure (180), e.g. second hash table or unstable hash table. The second data structure (180) stores all the memory pages that have been scanned by one of the de-duplication processes but cannot be or has not been subject to a merge with another memory page since no other identical memory page has been detected, while the first data structure (170) stores memory pages that have been merged. The first and second data structures, (170) and (180), respectively, shown and described herein are open hash tables, also known as a disjoint-set data structure which is a data structure that keeps track of a set of elements partitioned into a number of disjoint (non-overlapping) subsets. The disjoint-set data structure is a data structure representing a dynamic collection of sets. The disjoint-set data structure supports operations that create a new set containing a single element, returning a representative element, and replacing a first element in a first set and a second element in a second set with a union in the collection of sets.
As shown in
Both the first and second structures (170) and (180), respectively, are accessible by each of the de-duplication processes (1440), (1441), and (144N). The de-duplication processes (1440), (1441), and (144N), collaborate to merge pages within each operatively coupled element (1500), (1501), . . . (150N), including intra-element and across different elements, e.g. inter-element. As a memory page within or associated with one or more of the elements is assessed for de-duplication, the corresponding de-duplication process leverages a hash function to generate a hash code for the memory page. For example, page0,0 (1600,0) is local to element0,0 (1500), and as such is processed by de-duplication process0 (1440) to generate a corresponding hash code, with the hash code being a representation of the memory page. The de-duplication is directed two or more of the de-duplication processes, e.g. (1440), (1441), and (144N), operating in parallel, and accessing the first and second data structures (170) and (180), respectively, in parallel. The access of the data structures includes reading the entries therein, or in an embodiment, writing to the data structures to add, remove, or amend an entry therein. Duplicate entries as identified by their corresponding hash code representation are stored in the first structure (170) and non-duplicate entries are stored in the second structure (180). Details of the comparison and de-duplication, including conflict resolution via transactional memory associated with two or more de-duplication processes accessing the same data structure, are shown and described in
Referring to
As shown and described in
Each slot in the table can be in one of the following states: empty, occupied, or tombstone. An empty state means that no element has been inserted into this slot, an occupied state means that there is currently an element in this slot, and a tombstone state means there was an element in this slot, but the element was previously deleted and the slot is now empty. As shown and described herein, the starting position for the search is k MOD S. During the search, if the slot is occupied an assessment is conducted to determine if the elements match, if the slot is a tombstone slot, the slot is skipped and the search proceeds to the next slot, and if the slot is empty the search concludes.
Following step (408), an assessment is conducted to determine if the slot identified at step (408) is empty in the corresponding data structure (410). A positive response to the determination is an indication that no entry was found in the identified slot (412), and the process returns to step (208) in
A negative response to the determination at step (422) is followed by a further assessment of the entry found in the data structure. The initial assessment is identification of matching values of k MOD S. It is understood that similar, but not identical, memory pages may have the same k MOD S value, but different hash value, e.g. meaning they are different memory pages. As shown, following the negative response to the determination at step (422), it is determined if the hash values of the page being searched and the page in the slot match (426). A negative response to the determination at step (426) is an indication that the hash values do not match and is followed by a return to step (416) to ascertain if there is another slot in data structure that may have a matching object, and a positive response is followed by a comparison of the content in the slot with the hash value of the memory page under consideration, e.g. p, (428). It is then determined if the contents match (430). A negative response to the determination at step (430) is followed by a return to step (416), and a positive response is followed by a return of the page found in the data structure (432), and a returned to step (208) in
As shown and described in
Returning to
A positive response to the determination at step (224) is an indication that memory page p and memory page p1 are identical and subject to de-duplication. As shown, memory page p1 is removed from the first data structure (232), and a stop transactional memory instruction is issued, e.g.
The data structures shown and described herein are two separate data structures, also referred to herein as structures, e.g. first structure (170) and second structure (180), and are created and utilized herein with respect to memory page de-duplication. In one embodiment, the first structure (170) is also referred to herein as a stable table (ST) and the second structure (180) is referred to herein as an unstable table (UT). Both the first and second structures (170) and (180), respectively, are each disjoint-set data structures. The UT and the ST are shared among two or more de-duplication processes, and as such two or more de-duplication processes may access the UT and ST in parallel. The UT originates as an empty table, e.g. non populated, and becomes populated as memory pages are subject to hash functions and corresponding hash codes are selectively populated into the UT. As the UT is selectively populated, the entries in the UT include non-merged memory pages, e.g. no identical memory pages. In contrast to the UT, the ST is a data structure wherein the entries are merged memory pages, e.g. the ST represents pages that have been merged. An entry in the ST may represent two or more memory pages. Accordingly, the UT and the ST are utilized in conjunction with the hash code representation of the pages to facilitate and enable the de-duplication.
The process of creating entries in both the UT and the ST is challenging since the UT and ST are shared by at least two de-duplication processes. At any one time, at least two or more de-duplication processes may be reading and writing data to the UT and/or the ST in parallel. Reading data from either or both the UT and the ST will not cause a conflict, however a conflict may arise when removing an entry from the UT or ST or creating an entry in the UT or ST. As shown in
As demonstrated herein, the de-duplication of the memory pages utilizes separate de-duplication processes for each element, which in one embodiment may be a virtual machine, while allowing the de-duplication processes to access, e.g. read, the UT and ST in parallel. The memory of each element is processed by a single de-duplication process. Multiple de-duplication processes collaborate to merge memory pages not only within each element, but also across different elements. As shown in
Transactional memory solves concurrent access conflicts in an efficient and convenient manner. Page comparison operations described herein are also referred to as a read operation, and UT and ST table modifications that include adding an entry or removing an entry are also referred to as write operations. In one embodiment, the quantity of read operations on the ST and UT may exceed the quantity of write operations on the ST and UT. As shown and described in
As shown and described in
With references to
Host (502) may be described in the general context of computer system-executable instructions, such as program modules, being executed by a computer system. Generally, program modules may include routines, programs, objects, components, logic, data structures, and so on that perform particular tasks or implement particular abstract data types. Host (502) may be practiced in distributed cloud computing environments (510) where tasks are performed by remote processing devices that are linked through a communications network. In a distributed cloud computing environment, program modules may be located in both local and remote computer system storage media including memory storage devices.
As shown in
Memory (506) can include computer system readable media in the form of volatile memory, such as random access memory (RAM) (530) and/or cache memory (532). By way of example only, storage system (534) can be provided for reading from and writing to a non-removable, non-volatile magnetic media (not shown and typically called a “hard drive”). Although not shown, a magnetic disk drive for reading from and writing to a removable, non-volatile magnetic disk (e.g., a “floppy disk”), and an optical disk drive for reading from or writing to a removable, non-volatile optical disk such as a CD-ROM, DVD-ROM or other optical media can be provided. In such instances, each can be connected to bus (508) by one or more data media interfaces.
Program/utility (540), having a set (at least one) of program modules (542), may be stored in memory (506) by way of example, and not limitation, as well as an operating system, one or more application programs, other program modules, and program data. Each of the operating systems, one or more application programs, other program modules, and program data or some combination thereof, may include an implementation of a networking environment. Program modules (542) generally carry out the functions and/or methodologies of embodiments of the de-duplication mechanism shown and described in
Host (502) may also communicate with one or more external devices (514), such as a keyboard, a pointing device, a sensory input device, a sensory output device, etc.; a display (524); one or more devices that enable a user to interact with host (502); and/or any devices (e.g., network card, modem, etc.) that enable host (502) to communicate with one or more other computing devices. Such communication can occur via Input/Output (I/O) interface(s) (522). Still yet, host (502) can communicate with one or more networks such as a local area network (LAN), a general wide area network (WAN), and/or a public network (e.g., the Internet) via network adapter (520). As depicted, network adapter (520) communicates with the other components of host (502) via bus (508). In one embodiment, a plurality of nodes of a distributed file system (not shown) is in communication with the host (502) via the I/O interface (522) or via the network adapter (520). It should be understood that although not shown, other hardware and/or software components could be used in conjunction with host (502). Examples, include, but are not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data archival storage systems, etc.
In this document, the terms “computer program medium,” “computer usable medium,” and “computer readable medium” are used to generally refer to media such as main memory (506), including RAM (530), cache (532), and storage system (534), such as a removable storage drive and a hard disk installed in a hard disk drive.
Computer programs (also called computer control logic) are stored in memory (506). Computer programs may also be received via a communication interface, such as network adapter (520). Such computer programs, when run, enable the computer system to perform the features of the present embodiments as discussed herein. In particular, the computer programs, when run, enable the processing unit (504) to perform the features of the computer system. Accordingly, such computer programs represent controllers of the computer system.
In one embodiment, host (502) is a node of a cloud computing environment. As is known in the art, cloud computing is a model of service delivery for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, network bandwidth, servers, processing, memory, storage, applications, virtual machines, and services) that can be rapidly provisioned and released with minimal management effort or interaction with a provider of the service. This cloud model may include at least five characteristics, at least three service models, and at least four deployment models. Example of such characteristics are as follows:
On-demand self-service: a cloud consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with the service's provider.
Broad network access: capabilities are available over a network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, laptops, and PDAs).
Resource pooling: the provider's computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to demand. There is a sense of location independence in that the consumer generally has no control or knowledge over the exact location of the provided resources but may be able to specify location at a higher layer of abstraction (e.g., country, state, or datacenter).
Rapid elasticity: capabilities can be rapidly and elastically provisioned, in some cases automatically, to quickly scale out and rapidly released to quickly scale in. To the consumer, the capabilities available for provisioning often appear to be unlimited and can be purchased in any quantity at any time.
Measured service: cloud systems automatically control and optimize resource use by leveraging a metering capability at some layer of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported providing transparency for both the provider and consumer of the utilized service.
Service Models are as follows:
Software as a Service (SaaS): the capability provided to the consumer is to use the provider's applications running on a cloud infrastructure. The applications are accessible from various client devices through a thin client interface such as a web browser (e.g., web-based email). The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings.
Platform as a Service (PaaS): the capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages and tools supported by the provider. The consumer does not manage or control the underlying cloud infrastructure including networks, servers, operating systems, or storage, but has control over the deployed applications and possibly application hosting environment configurations.
Infrastructure as a Service (IaaS): the capability provided to the consumer is to provision processing, storage, networks, and other fundamental computing resources where the consumer is able to deploy and run arbitrary software, which can include operating systems and applications. The consumer does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, deployed applications, and possibly limited control of select networking components (e.g., host firewalls).
Deployment Models are as follows:
Private cloud: the cloud infrastructure is operated solely for an organization. It may be managed by the organization or a third party and may exist on-premises or off-premises.
Community cloud: the cloud infrastructure is shared by several organizations and supports a specific community that has shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be managed by the organizations or a third party and may exist on-premises or off-premises.
Public cloud: the cloud infrastructure is made available to the general public or a large industry group and is owned by an organization selling cloud services.
Hybrid cloud: the cloud infrastructure is a composition of two or more clouds (private, community, or public) that remain unique entities but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load balancing between clouds).
A cloud computing environment is service oriented with a focus on statelessness, low coupling, modularity, and semantic interoperability. At the heart of cloud computing is an infrastructure comprising a network of interconnected nodes.
Referring now to
Referring now to
Virtualization layer (720) provides an abstraction layer from which the following examples of virtual entities may be provided: virtual servers; virtual storage; virtual networks, including virtual private networks; virtual applications and operating systems; and virtual clients.
In one example, management layer (730) may provide the following functions: resource provisioning, metering and pricing, user portal, service layer management, and SLA planning and fulfillment. Resource provisioning provides dynamic procurement of computing resources and other resources that are utilized to perform tasks within the cloud computing environment. Metering and pricing provides cost tracking as resources are utilized within the cloud computing environment, and billing or invoicing for consumption of these resources. In one example, these resources may comprise application software licenses. Security provides identity verification for cloud consumers and tasks, as well as protection for data and other resources. User portal provides access to the cloud computing environment for consumers and system administrators. Service layer management provides cloud computing resource allocation and management such that required service layers are met. Service Layer Agreement (SLA) planning and fulfillment provides pre-arrangement for, and procurement of, cloud computing resources for which a future requirement is anticipated in accordance with an SLA.
Workloads layer (740) provides examples of functionality for which the cloud computing environment may be utilized. Examples of workloads and functions which may be provided from this layer include, but are not limited to: mapping and navigation; software development and lifecycle management; virtual classroom education delivery; data analytics processing; transaction processing; and memory page de-duplication.
While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from this invention and its broader aspects. Therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of this invention. Furthermore, it is to be understood that the invention is solely defined by the appended claims. It will be understood by those with skill in the art that if a specific number of an introduced claim element is intended, such intent will be explicitly recited in the claim, and in the absence of such recitation no such limitation is present. For non-limiting example, as an aid to understanding, the following appended claims contain usage of the introductory phrases “at least one” and “one or more” to introduce claim elements. However, the use of such phrases should not be construed to imply that the introduction of a claim element by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an”; the same holds true for the use in the claims of definite articles.
The present invention may be a system, a method, and/or a computer program product. In addition, selected aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and/or hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, aspects of the present invention may take the form of computer program product embodied in a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention. Thus embodied, the disclosed system, a method, and/or a computer program product are operative to improve the functionality and operation of information retrieval by directing activity, and in one embodiment authoring activity, towards identified gaps in corpora of knowledge.
The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a dynamic or static random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a magnetic storage device, a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire.
Computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device.
Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like, and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server or cluster of servers. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention.
Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions.
These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks.
The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks.
The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions.
It will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. In particular, the first and second structures (170) and (180) may be modified so that each entry can be associated with a list, and the items in the list represent the memory pages with the same hash value but different content. Accordingly, the scope of protection of this invention is limited only by the following claims and their equivalents.
