U.S. patent application number 13/588050 was filed with the patent office on 2014-02-20 for virtual machine image access de-duplication.
This patent application is currently assigned to INTERNATIONAL BUSINESS MACHINES CORPORATION. The applicant listed for this patent is Han Chen, Alexei A. Karve, Minkyong Kim, Andrzej P. Kochut, Hui Lei, Jayaram Kallapalayam Radhakrishnan, Zhiming Shen, Zhe Zhang. Invention is credited to Han Chen, Alexei A. Karve, Minkyong Kim, Andrzej P. Kochut, Hui Lei, Jayaram Kallapalayam Radhakrishnan, Zhiming Shen, Zhe Zhang.
Application Number | 20140050407 13/588050 |
Document ID | / |
Family ID | 50100080 |
Filed Date | 2014-02-20 |
United States Patent
Application |
20140050407 |
Kind Code |
A1 |
Chen; Han ; et al. |
February 20, 2014 |
Virtual Machine Image Access De-Duplication
Abstract
Techniques for de-duplicating virtual machine image accesses. A
method includes identifying one or more identical blocks in two or
more images in a virtual machine image repository, generating a
block map for mapping different blocks with identical content into
a same block, deploying a virtual machine image by reconstituting
an image from the block map and fetching any unique blocks remotely
on-demand, and de-duplicating virtual machine image accesses by
storing the deployed virtual machine image in a local disk
cache.
Inventors: |
Chen; Han; (White Plains,
NY) ; Karve; Alexei A.; (Mohegan Lake, NY) ;
Kim; Minkyong; (Scarsdale, NY) ; Kochut; Andrzej
P.; (Croton on Hudson, NY) ; Lei; Hui;
(Scarsdale, NY) ; Radhakrishnan; Jayaram
Kallapalayam; (Raleigh, NC) ; Shen; Zhiming;
(Raleigh, NC) ; Zhang; Zhe; (Elmsford,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chen; Han
Karve; Alexei A.
Kim; Minkyong
Kochut; Andrzej P.
Lei; Hui
Radhakrishnan; Jayaram Kallapalayam
Shen; Zhiming
Zhang; Zhe |
White Plains
Mohegan Lake
Scarsdale
Croton on Hudson
Scarsdale
Raleigh
Raleigh
Elmsford |
NY
NY
NY
NY
NY
NC
NC
NY |
US
US
US
US
US
US
US
US |
|
|
Assignee: |
INTERNATIONAL BUSINESS MACHINES
CORPORATION
Armonk
NY
|
Family ID: |
50100080 |
Appl. No.: |
13/588050 |
Filed: |
August 17, 2012 |
Current U.S.
Class: |
382/195 |
Current CPC
Class: |
G06F 9/45558 20130101;
G06F 2009/45562 20130101 |
Class at
Publication: |
382/195 |
International
Class: |
G06K 9/46 20060101
G06K009/46 |
Claims
1. A method for de-duplicating virtual machine image accesses, the
method comprising: identifying one or more identical blocks in two
or more images in a virtual machine image repository; generating a
block map for mapping different blocks with identical content into
a same block; deploying a virtual machine image by reconstituting
an image from the block map and fetching any unique blocks remotely
on-demand; and de-duplicating virtual machine image accesses by
storing the deployed virtual machine image in a local disk cache;
wherein at least one of the steps is carried out by a computer
device.
2. The method of claim 1, comprising redirecting a read request to
a set of destination addresses based on the block map upon
receiving the read request for a set of blocks at any cache
device.
3. The method of claim 1, comprising consolidating the block map by
merging continuous blocks.
4. The method of claim 1, wherein generating a block map comprises
generating a block map when a file is created at any set of storage
computers.
5. The method of claim 1, comprising propagating the block map to
one or more cache devices.
6. The method of claim 5, wherein the one or more cache devices
comprise an operating system page cache and/or a local disk
cache.
7. The method of claim 1, wherein each entry in the block map
points a set of file blocks to a set of destination addresses based
on content of the set of file blocks.
8. The method of claim 7, wherein the destination addresses in the
block map are in the form of file blocks and include a file
identifier and an offset.
9. The method of claim 8, wherein the file identifier is a node
number.
10. The method of claim 7, comprising redirecting a read request to
a set of destination addresses based on the block map upon
receiving the read request for a set of file blocks at any cache
device.
11. The method of claim 1, comprising managing the local disk cache
via affording file blocks appearing in early positions in the cache
higher priority to stay in the cache.
12. The method of claim 1, comprising providing run-time support by
redirecting image accesses to different base images.
13. The method of claim 1, comprising expediting look-up operations
via a binary search.
14. The method of claim 1, comprising expediting look-up operations
via a bloom filter.
Description
FIELD OF THE INVENTION
[0001] Embodiments of the invention generally relate to information
technology, and, more particularly, to caching for virtual machine
(VM) images.
BACKGROUND
[0002] Challenges exist in the de-duplication of virtual machine
(VM) images. Input/output (I/O) contention occurs when accessing VM
images, and managing such contention can be important for
application performance, user experience, infrastructure cost, etc.
However, challenges can arise due to, for example, a high density
virtualized environment, a large number of VM images, and/or
limited resources (memory and disk space) for caching images
locally on compute nodes.
[0003] Different VM images often have common portions of data.
Reasons for similarity can include, for example, similar operating
systems, similar applications, and/or the fact that many new images
are created by slightly modifying existing images. Accordingly, VM
image access de-duplication aims to avoid I/O operations on blocks
with identical content.
[0004] Existing approaches include on-demand streaming of a VM
image, which includes copy-on-read (CoR), copy-on-write (CoW), and
adaptive pre-fetching. Such approaches, however, do not exploit
image similarity. Existing approaches can also include the use of a
de-duplicated VM image repository. Such approaches attempt to
exploit image similarity to combat image sprawl, but lack run-time
support (that is, retrieving an image requires reconstituting and
copying the entire image).
[0005] Other approaches include a general de-duplicated file
system, which attempts to exploit file content similarity to reduce
disk space occupation, but requires replacing existing file
systems. Also, such approaches only consider de-duplicating block
allocation instead of file access. Additionally, existing
approaches can include VM memory page/cache sharing. Such
approaches attempt to discover and share identical memory pages by
content scanning or exchanging page information, but introduce high
overhead costs.
SUMMARY
[0006] In one aspect of the present invention, techniques for
virtual machine image access de-duplication are provided. An
exemplary computer-implemented method for de-duplicating virtual
machine image accesses can include steps of identifying one or more
identical blocks in two or more images in a virtual machine image
repository, generating a block map for mapping different blocks
with identical content into a same block, deploying a virtual
machine image by reconstituting an image from the block map and
fetching any unique blocks remotely on-demand, and de-duplicating
virtual machine image accesses by storing the deployed virtual
machine image in a local disk cache.
[0007] Another aspect of the invention or elements thereof can be
implemented in the form of an article of manufacture tangibly
embodying computer readable instructions which, when implemented,
cause a computer to carry out a plurality of method steps, as
described herein. Furthermore, another aspect of the invention or
elements thereof can be implemented in the form of an apparatus
including a memory and at least one processor that is coupled to
the memory and operative to perform noted method steps. Yet
further, another aspect of the invention or elements thereof can be
implemented in the form of means for carrying out the method steps
described herein, or elements thereof; the means can include (i)
hardware module(s), (ii) software module(s), or (iii) a combination
of hardware and software modules; any of (i)-(iii) implement the
specific techniques set forth herein, and the software modules are
stored in a tangible computer-readable storage medium (or multiple
such media).
[0008] These and other objects, features and advantages of the
present invention will become apparent from the following detailed
description of illustrative embodiments thereof, which is to be
read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a diagram illustrating the concept of discovering
identical blocks, according to an embodiment of the present
invention;
[0010] FIG. 2 is a diagram illustrating the concept of image access
de-duplication, according to an embodiment of the present
invention;
[0011] FIG. 3 is a block diagram illustrating an example
embodiment, according to an aspect of the invention;
[0012] FIG. 4 is a flow diagram illustrating techniques for
de-duplicating virtual machine image accesses, according to an
embodiment of the invention; and
[0013] FIG. 5 is a system diagram of an exemplary computer system
on which at least one embodiment of the invention can be
implemented.
DETAILED DESCRIPTION
[0014] As described herein, an aspect of the present invention
includes content-aware caching for virtual machine images. As noted
above, challenges exist in efficient de-duplication of virtual
machine images. Existing approaches are based on fixed or variable
size chunks, which require significant changes to existing
operating systems. Aspects of the invention, as detailed herein,
are based on pair-wise similarity between virtual machine
images.
[0015] At least one embodiment of the invention includes
redirecting I/O accesses to an image A to another image B which is
available in a memory or local disk cache. Meanwhile, the
underlying storage of virtual machine images is in the original
format. Accordingly, aspects of the invention include virtual
machine image access de-duplication.
[0016] As described herein, many accesses to a local disk and/or
remote VM repository are for blocks with identical content. One
technique for identifying or determining block content includes
comparing two or more blocks bit by bit. Another technique includes
calculating the hash value of each block and combining all blocks
with the same hash value. Accordingly, VM image accesses can be
de-duplicated by sharing cache. At least one embodiment of the
invention includes translating accesses to different blocks with
the same content into accesses to the same blocks. After detecting
that a first block and a second block have the same content, upon
receipt of a request for the first block, at least one embodiment
of the invention includes redirecting the request to the second
block.
[0017] Additionally, an image can be logically constructed from
existing images without data transfer. Using the redirection
described above, at least one embodiment of the invention includes
redirecting requests to blocks of image_x to other images residing
on the computer, without transferring all blocks of image_x from
the storage server.
[0018] Further, aspects of the invention also include on-demand
fetching of requested blocks, and disk caching for saving network
bandwidth usage. The requested blocks are fetched from the storage
server, which is connected via a network to the compute node. After
being fetched from the storage server, some data blocks (belonging
to some images) are cached on the hard disk of the compute node.
Accordingly, when those blocks are requested again by a VM, the
requests can be served from the local compute node disk instead of
having to transfer from the storage server. As a result, network
bandwidth is saved.
[0019] FIG. 1 is a diagram illustrating the concept of discovering
identical blocks, according to an embodiment of the present
invention. By way of illustration, FIG. 1 depicts image 1 (102),
image 2 (104) and shared blocks 106 discovered, for example, via
hashing.
[0020] FIG. 2 is a diagram illustrating the concept of image access
de-duplication, according to an embodiment of the present
invention. By way of illustration, FIG. 2 depicts image 1 (202),
image 1' (204), image 2 (206) and image 2' (208). The depiction of
FIG. 2 corresponds to the translating step detailed herein. For
example, requests to the 1.sup.st and 2.sup.nd blocks of image 2
(206) are translated to the 1.sup.st block of image 1 (202). The
"prime" indications here refer to conceptual images; that is, the
image appears to the VM as a real image, but does not contain real
data blocks.
[0021] Image access de-duplication such as depicted in FIG. 2
provides advantages over using raw images. For example, performance
can be improved by sharing cache among VMs accessing blocks with
the same content. Additionally, resource utilization can be made
more efficient by saving memory and network bandwidth. Also, image
access de-duplication such as depicted in FIG. 2 provides
advantages over using de-duplicated file systems. For example, at
least one embodiment of the invention offers an ease of deployment,
and can work with an unmodified file system and VM repository.
Additionally, image access de-duplication preserves storage layout,
and is friendlier to sequential reads.
[0022] FIG. 3 is a block diagram illustrating an example
embodiment, according to an aspect of the invention. By way of
illustration, FIG. 3 depicts a computation node 302 and an image
repository 304. Computation node 302 includes virtual machines 306
with copy-on-write portions, V-union device mapper components 308,
loop devices 310, a virtual file system (VFS) (memory page cache)
312, virtual memory integrated cloud (VMIC) device mapper
components 314 (that is, a disk cache as described herein), a local
disk cache 316 and Internet small computer system interface (iSCSI)
devices 318. Additionally, image repository 304 includes images 320
and a block map generator component 322.
[0023] As depicted in FIG. 3, each arrow represents a request
between components. VMs 1-3 are different VMs running on the same
computer. CoW denotes the copy-on-write files supporting the VMs.
Copy-on-write is a technology to create snapshot files to store
"dirty" data and avoid modifying the image file itself. Each CoW
file will handle requests to "dirty" data of a VM. Therefore, all
requests to "clean" data will bypass the CoW file, and go to the
V-union device mapper 308. The V-union device mapper will redirect
the requests according to the pre-calculated mapping rules (for
example, the V-union device mapper for VM1 has arrows to the loop
devices for VM2 and VM3).
[0024] The loop device 310 underneath each VM is a way to present a
device interface from a regular file. The loop device will forward
the received (redirected) requests to the OS VFS layer. This action
will go through memory page cache 312. Additionally, the requests
will be forwarded to VMIC devices 314. Each VMIC device is a disk
cache corresponding to a VM image, and temporarily stores some VM
image data on the local disk to avoid frequent accesses to remote
storage repository. If a block of data is not found in the local
disk cache 316, the request is forwarded to the storage repository
304 through the iSCSI protocol.
[0025] FIG. 4 is a flow diagram illustrating techniques for
de-duplicating virtual machine image accesses, according to an
embodiment of the invention. Step 402 includes identifying one or
more identical blocks in two or more images in a virtual machine
image repository.
[0026] Step 404 includes generating a block map for mapping
different blocks with identical content into a same block.
Generating a block map can include generating a block map when a
file is created at any set of storage computers. The block map can
additionally be consolidated by merging continuous blocks, and the
block map can also be propagated to one or more cache devices (for
example, an operating system page cache and/or a local disk
cache).
[0027] In at least one embodiment of the invention, each entry in
the block map points a set of file blocks to a set of destination
addresses based on content of the set of file blocks. The
destination addresses in the block map can be in the form of file
blocks and include a file identifier (for example, a node number)
and an offset. At least one embodiment of the invention can
additionally include redirecting a read request to a set of
destination addresses based on the block map upon receiving the
read request for a set of file blocks at any cache device.
[0028] Step 406 includes deploying a virtual machine image by
reconstituting an image from the block map and fetching any unique
blocks remotely on-demand. Step 408 includes de-duplicating virtual
machine image accesses by storing the deployed virtual machine
image in a local disk cache. At least one embodiment of the
invention can also include managing the local disk cache. Managing
the local disk cache can include, for example, affording file
blocks appearing in early positions in the cache higher priority to
stay in the cache.
[0029] Further, at least one embodiment of the invention includes
redirecting a read request to a set of destination addresses based
on the block map upon receiving the read request for a set of
blocks at any cache device. The techniques depicted in FIG. 4 can
additionally include providing run-time support by redirecting
image accesses to different base images. Further, at least one
embodiment of the invention includes expediting look-up operations
via a binary search, a bloom filter, etc.
[0030] The techniques depicted in FIG. 4 can also, as described
herein, include providing a system, wherein the system includes
distinct software modules, each of the distinct software modules
being embodied on a tangible computer-readable recordable storage
medium. All of the modules (or any subset thereof) can be on the
same medium, or each can be on a different medium, for example. The
modules can include any or all of the components shown in the
figures and/or described herein. In an aspect of the invention, the
modules can run, for example, on a hardware processor. The method
steps can then be carried out using the distinct software modules
of the system, as described above, executing on a hardware
processor.
[0031] By way of example, in at least one embodiment of the
invention, distinct software modules can include a metadata module,
an access mapping module and a local disk cache management module.
In such an example embodiment, the metadata module identifies one
or more identical blocks in two or more images in a virtual machine
image repository and generates a block map for mapping different
blocks with identical content into a same block. Additionally, the
access mapping module redirects virtual machine image accesses
according to the block map, and the local disk cache management
module fetches blocks remotely on-demand and stores virtual machine
images in a local disk cache.
[0032] Further, a computer program product can include a tangible
computer-readable recordable storage medium with code adapted to be
executed to carry out at least one method step described herein,
including the provision of the system with the distinct software
modules.
[0033] Additionally, the techniques depicted in FIG. 4 can be
implemented via a computer program product that can include
computer useable program code that is stored in a computer readable
storage medium in a data processing system, and wherein the
computer useable program code was downloaded over a network from a
remote data processing system. Also, in an aspect of the invention,
the computer program product can include computer useable program
code that is stored in a computer readable storage medium in a
server data processing system, and wherein the computer useable
program code is downloaded over a network to a remote data
processing system for use in a computer readable storage medium
with the remote system.
[0034] As will be appreciated by one skilled in the art, aspects of
the present invention may be embodied as a system, method or
computer program product. Accordingly, 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
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 a computer program product
embodied in a computer readable medium having computer readable
program code embodied thereon.
[0035] An aspect of the invention or elements thereof can be
implemented in the form of an apparatus including a memory and at
least one processor that is coupled to the memory and operative to
perform exemplary method steps.
[0036] Additionally, an aspect of the present invention can make
use of software running on a general purpose computer or
workstation. With reference to FIG. 5, such an implementation might
employ, for example, a processor 502, a memory 504, and an
input/output interface formed, for example, by a display 506 and a
keyboard 508. The term "processor" as used herein is intended to
include any processing device, such as, for example, one that
includes a CPU (central processing unit) and/or other forms of
processing circuitry. Further, the term "processor" may refer to
more than one individual processor. The term "memory" is intended
to include memory associated with a processor or CPU, such as, for
example, RAM (random access memory), ROM (read only memory), a
fixed memory device (for example, hard drive), a removable memory
device (for example, diskette), a flash memory and the like. In
addition, the phrase "input/output interface" as used herein, is
intended to include, for example, a mechanism for inputting data to
the processing unit (for example, mouse), and a mechanism for
providing results associated with the processing unit (for example,
printer). The processor 502, memory 504, and input/output interface
such as display 506 and keyboard 508 can be interconnected, for
example, via bus 510 as part of a data processing unit 512.
Suitable interconnections, for example via bus 510, can also be
provided to a network interface 514, such as a network card, which
can be provided to interface with a computer network, and to a
media interface 516, such as a diskette or CD-ROM drive, which can
be provided to interface with media 518.
[0037] Accordingly, computer software including instructions or
code for performing the methodologies of the invention, as
described herein, may be stored in associated memory devices (for
example, ROM, fixed or removable memory) and, when ready to be
utilized, loaded in part or in whole (for example, into RAM) and
implemented by a CPU. Such software could include, but is not
limited to, firmware, resident software, microcode, and the
like.
[0038] A data processing system suitable for storing and/or
executing program code will include at least one processor 502
coupled directly or indirectly to memory elements 504 through a
system bus 510. The memory elements can include local memory
employed during actual implementation of the program code, bulk
storage, and cache memories which provide temporary storage of at
least some program code in order to reduce the number of times code
must be retrieved from bulk storage during implementation.
[0039] Input/output or I/O devices (including but not limited to
keyboards 508, displays 506, pointing devices, and the like) can be
coupled to the system either directly (such as via bus 510) or
through intervening I/O controllers (omitted for clarity).
[0040] Network adapters such as network interface 514 may also be
coupled to the system to enable the data processing system to
become coupled to other data processing systems or remote printers
or storage devices through intervening private or public networks.
Modems, cable modem and Ethernet cards are just a few of the
currently available types of network adapters.
[0041] As used herein, including the claims, a "server" includes a
physical data processing system (for example, system 512 as shown
in FIG. 5) running a server program. It will be understood that
such a physical server may or may not include a display and
keyboard.
[0042] As noted, aspects of the present invention may take the form
of a computer program product embodied in a computer readable
medium having computer readable program code embodied thereon.
Also, any combination of computer readable media may be utilized.
The computer readable medium may be a computer readable signal
medium or a computer readable storage medium. A computer readable
storage medium may be, for example, but not limited to, an
electronic, magnetic, optical, electromagnetic, infrared, or
semiconductor system, apparatus, or device, or any suitable
combination of the foregoing. More specific examples (a
non-exhaustive list) of the computer readable storage medium would
include the following: an electrical connection having one or more
wires, a portable computer diskette, a hard disk, a random access
memory (RAM), a read-only memory (ROM), an erasable programmable
read-only memory (EPROM or Flash memory), an optical fiber, a
portable compact disc read-only memory (CD-ROM), an optical storage
device, a magnetic storage device, or any suitable combination of
the foregoing. In the context of this document, a computer readable
storage medium may be any tangible medium that can contain, or
store a program for use by or in connection with an instruction
execution system, apparatus, or device.
[0043] A computer readable signal medium may include a propagated
data signal with computer readable program code embodied therein,
for example, in baseband or as part of a carrier wave. Such a
propagated signal may take any of a variety of forms, including,
but not limited to, electro-magnetic, optical, or any suitable
combination thereof. A computer readable signal medium may be any
computer readable medium that is not a computer readable storage
medium and that can communicate, propagate, or transport a program
for use by or in connection with an instruction execution system,
apparatus, or device.
[0044] Program code embodied on a computer readable medium may be
transmitted using an appropriate medium, including but not limited
to wireless, wireline, optical fiber cable, RF, etc., or any
suitable combination of the foregoing.
[0045] Computer program code for carrying out operations for
aspects of the present invention may be written in any combination
of at least one programming language, 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 program
code 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. 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).
[0046] 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 program
instructions. These computer 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.
[0047] These computer program instructions may also be stored in a
computer readable medium that can direct a computer, other
programmable data processing apparatus, or other devices to
function in a particular manner, such that the instructions stored
in the computer readable medium produce an article of manufacture
including instructions which implement the function/act specified
in the flowchart and/or block diagram block or blocks. Accordingly,
an aspect of the invention includes an article of manufacture
tangibly embodying computer readable instructions which, when
implemented, cause a computer to carry out a plurality of method
steps as described herein.
[0048] The computer program instructions may also be loaded onto a
computer, other programmable data processing apparatus, or other
devices to cause a series of operational steps to be performed on
the computer, other programmable apparatus or other devices to
produce a computer implemented process such that the instructions
which execute on the computer or other programmable apparatus
provide processes for implementing the functions/acts specified in
the flowchart and/or block diagram block or blocks.
[0049] 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, component, segment, or portion of code, which comprises
at least one executable instruction for implementing the specified
logical function(s). It should also be noted that, 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 combinations of special purpose hardware and
computer instructions.
[0050] It should be noted that any of the methods described herein
can include an additional step of providing a system comprising
distinct software modules embodied on a computer readable storage
medium; the modules can include, for example, any or all of the
components detailed herein. The method steps can then be carried
out using the distinct software modules and/or sub-modules of the
system, as described above, executing on a hardware processor 502.
Further, a computer program product can include a computer-readable
storage medium with code adapted to be implemented to carry out at
least one method step described herein, including the provision of
the system with the distinct software modules.
[0051] In any case, it should be understood that the components
illustrated herein may be implemented in various forms of hardware,
software, or combinations thereof, for example, application
specific integrated circuit(s) (ASICS), functional circuitry, an
appropriately programmed general purpose digital computer with
associated memory, and the like. Given the teachings of the
invention provided herein, one of ordinary skill in the related art
will be able to contemplate other implementations of the components
of the invention.
[0052] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a," "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of another feature, integer, step,
operation, element, component, and/or group thereof.
[0053] The corresponding structures, materials, acts, and
equivalents of all means or step plus function elements in the
claims below are intended to include any structure, material, or
act for performing the function in combination with other claimed
elements as specifically claimed.
[0054] At least one aspect of the present invention may provide a
beneficial effect such as, for example, sharing a cache among VM
accessing blocks with the same content.
[0055] The descriptions of the various embodiments of the present
invention have been presented for purposes of illustration, but are
not intended to be exhaustive or limited to the embodiments
disclosed. Many modifications and variations will be apparent to
those of ordinary skill in the art without departing from the scope
and spirit of the described embodiments. The terminology used
herein was chosen to best explain the principles of the
embodiments, the practical application or technical improvement
over technologies found in the marketplace, or to enable others of
ordinary skill in the art to understand the embodiments disclosed
herein.
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