Abstract:
Embodiments of the invention relate to counter-based entry invalidation for a metadata previous write queue (PWQ). An aspect of the invention includes writing an address into an entry in the metadata PWQ, the address being associated with an instance of metadata received from a pipeline and setting a valid tag associated with the entry in the metadata PWQ to valid. Another aspect of the invention includes initializing a counter to zero and incrementing the counter based on receiving a count signal from the pipeline until the counter is equal to a threshold. Yet another aspect of the invention includes setting the valid tag to invalid based on the counter being equal to the threshold.

Description:
BACKGROUND 
       [0001]    The present invention relates generally to computer processing systems, and more specifically, to a metadata previous write queue associated with a metadata store in a processor. 
         [0002]    A computer program that is executed by a processor in a computing system may be broken down into a series of operations. A pipeline architecture of the processor comprises a plurality of stages, and the operations proceed through the various stages of the pipeline during execution. In order to assist a processor pipeline in the execution of a computer program so that the execution may be relatively fast and efficient, metadata regarding various operations, such as instructions or data fetches, may be stored in a metadata store that is associated with the processor. The metadata may include, but is not limited to, data predicting the direction of a branch, data regarding the dependency between two instructions, or may relate to a data fetch, and may be indexed in the metadata store based on an address associated with the metadata. Subsequent executions of the same operation may produce identical instances of metadata. It is preferred to not write any particular instance of metadata into the metadata store more than once. While writing the same metadata into multiple sets in the metadata store may not be a data integrity concern, overall performance of the microprocessor may be reduced by the presence of duplicate entries in the metadata store, as other unique entries that would further assist in program performance may be displaced. 
         [0003]    It may be relatively time-consuming and/or power consuming to search the metadata store to determine if a given metadata entry is already in the metadata store prior to writing the metadata entry into the metadata store. Therefore, in order to prevent duplicate metadata store entries, an operation may have a metadata marking, which indicates that a metadata entry already exists in the metadata store for the particular operation. Additionally, a previous write queue (PWQ) may be used to track the most recent entries that were written into in the metadata store. When a new entry is ready to be written into the metadata store, the new entry may be compared to the metadata PWQ, and, if there is a valid match for the address associated with the operation in the metadata PWQ, it is determined that the new entry is already in the metadata store and does not need to be written into the metadata store again. 
       SUMMARY 
       [0004]    Embodiments include a method, system, and computer program product for counter-based entry invalidation for a metadata previous write queue (PWQ). An aspect of the invention includes writing an address into an entry in the metadata PWQ, the address being associated with an instance of metadata received from a pipeline and setting a valid tag associated with the entry in the metadata PWQ to valid. Another aspect of the invention includes initializing a counter to zero and incrementing the counter based on receiving a count signal from the pipeline until the counter is equal to a threshold. Yet another aspect of the invention includes setting the valid tag to invalid based on the counter being equal to the threshold. 
         [0005]    Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with advantages and features, refer to the description and to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0006]    The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The forgoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0007]      FIG. 1A  depicts a computing system in accordance with an embodiment; 
           [0008]      FIG. 1B  depicts a processor pipeline in accordance with an embodiment; 
           [0009]      FIG. 2  depicts a cache and a multi-set associative metadata store in accordance with an embodiment; 
           [0010]      FIG. 3  depicts a congruence class of entries in a metadata store in accordance with an embodiment; 
           [0011]      FIG. 4  depicts a metadata PWQ and a multi-set associative metadata store in accordance with an embodiment; 
           [0012]      FIGS. 5A-5B  depict systems for counter-based entry invalidation for a metadata PWQ in accordance with various embodiments; 
           [0013]      FIGS. 6-8  depict process flows for counter-based entry invalidation for a metadata PWQ in accordance with various embodiments; and 
           [0014]      FIG. 9  illustrates a computer program product in accordance with an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Embodiments of counter-based entry invalidation for a metadata PWQ are provided, with exemplary embodiments being discussed below in detail. In some situations, it is possible that an entry that is found in the metadata PWQ may not actually exist in the metadata store. Such an entry in the metadata PWQ may incorrectly block new metadata entries from being written into the metadata store. Therefore, entries in the metadata PWQ may be invalidated based on one or more counters in order to avoid incorrect blocking of entry writes into the metadata store. One or more thresholds may be defined for the one or more counters to ensure that an entry in the metadata PWQ will be invalidated after any other instances of the operation associated with the entry that are in the pipeline at the time of the writing of the entry into the metadata store have completed execution. A threshold may be a predetermined value based on the depth of the pipeline in some embodiments. In other embodiments, a threshold may be based on a total number of operations that are in the pipeline at the time of an initial write of an entry into the metadata PWQ. In further embodiments, a threshold may be based on a number of instances of a particular operation that are in the pipeline at the time of the initial write of an entry for the particular operation into the metadata PWQ. 
         [0016]    Each entry in the metadata PWQ may have an associated valid tag, and an entry may be invalidated by setting its associated valid tag to an appropriate value, e.g., false. Upon the initial write of an entry into the metadata PWQ, its associated valid bit is set active, e.g., true. When determining if a matching entry for an address exists in the metadata PWQ, the valid bit in the matching entry for the address is also checked, as in order to determine that a match for an address exists in the metadata PWQ, the valid bit in the matching entry for the address must be set to valid. Invalidated entries may be overwritten by new entries in the metadata PWQ. Such invalidation of entries in the metadata PWQ prevents incorrect blocking of new entries into the metadata store by the metadata PWQ. 
         [0017]      FIG. 1A  shows an illustrative embodiment of a computing system  10 . The computing system  10  includes a processor  11 , which has a cache  12 . The cache  12  may comprise any appropriate type of cache, such as an instruction cache, a branch table, or a data cache. The computing system additionally includes a main memory  13 . During execution of an operation, the processor  11  may check for the cache  12  for data regarding the operation. If the data regarding the operation is not present in cache  11 , the processor  11  may retrieve the data regarding the operation from main memory  13 .  FIG. 1B  shows an illustrative embodiment of a pipeline  100  having a plurality of stages  101 - 107 , which may be incorporated into processor  11  of  FIG. 1A . Operations proceed through the pipeline from fetch stage  101  through stages  102 - 106 , and are completed at checkpoint stage  107 . Metadata corresponding to operations in the pipeline  100  may be written into a metadata store that is associated with a metadata PWQ (discussed in further detail below) at checkpoint stage  107  in some embodiments. An operation may have any appropriate number of instances in the process of proceeding through pipeline  100  at once.  FIG. 1  is shown for illustrative purposes only; a pipeline may have any appropriate number of stages in various embodiments. 
         [0018]      FIG. 2  shows an embodiment of a system  200  including a cache  202  and a multi-set associative metadata store  203  that may be associated with a pipeline, such as pipeline  100  that was shown in  FIG. 1 . Cache  202  may comprise cache  12  as is shown in  FIG. 1A . The cache  202  may comprise any appropriate type of cache, such as an instruction cache, a branch table, or a data cache. The metadata in the metadata store  203  may be accessed in parallel with the cache  202  using an address  201 , which is an address that is associated with an operation, for example, that is currently being processed in the pipeline. The metadata store  203  may comprise an array that associates each instance of metadata with an address, which may comprise, for example, an instruction address or data fetch address. An entry may be written into the metadata store  203  when metadata for an operation becomes known after processing of the operation. Different types of metadata may become available at different stages of the pipeline. For example, branch content may be known at branch resolution, which occurs in a specific part of the pipeline; however, content on store/load instruction dependencies may only be known at the end of the pipeline.  FIG. 3  shows an embodiment of metadata store entries  300  in a metadata store congruence class, such as metadata store  203  of  FIG. 2 . Metadata store entries  300  include addresses  302 , which are associated with metadatas  303 . The input address  301 , which may comprise an address associated with an operation currently being processed in an associated pipeline, is used by hit logic  304  to determine if there is a match for input address  301  in the addresses  302  of the metadata store entries  300 . If hit logic  304  determines that there is a match, metadata  303  that is read out on metadata store output  306  via multiplexer  305  is used for processing of the operation associated with the address  301  in the pipeline. 
         [0019]      FIG. 4  shows an embodiment of a system  400  including a metadata PWQ  402  that is associated with a metadata store  408 . System  400  may be incorporated into cache  12  as is shown in  FIG. 1A . The metadata PWQ  402  as shown in  FIG. 4  includes  4  entries; however, this is shown for illustrative purposes only. The number of entries in a metadata PWQ may depend on, for example, the size of the metadata store associated with the metadata PWQ, or the depth of the pipeline associated with the metadata store. Each entry in the metadata PWQ  402  has a valid tag  403  and an address field  404 . Each entry&#39;s valid tag  403  is set to true or false (indicating whether the entry is valid or invalid) based on a counter, which is discussed in further detail below with respect to  FIGS. 5-8 . When an operation has metadata to write into the metadata store  408 , the address  401  for the operation and the metadata  405  are both stored in staging latch  407 . The hit logic  406  then determines if there is a match for the address  401  in an address field  404  in any of the entries in the metadata PWQ  402 . If there is a match for address  401  in the metadata PWQ  402 , it is then determined if the valid tag  403  associated with the matching address field  404  in the metadata PWQ is set to true, indicating a valid entry for the address in the metadata PWQ. If there is an entry in the metadata PWQ  402  comprising an address field  404  that matches address  401  that has its associated valid tag  403  set to true, hit logic  406  determines that there is a hit for the address  401  in the metadata PWQ  402 , and the metadata  405  and the write address  401  are not written into the metadata store  408 . However, if there is not a hit for the address  401  in the metadata PWQ  402 , the hit logic  406  instructs the staging latch  407  to write the metadata  405  and the write address  401  into an entry in the metadata store  408 , and additionally, a new entry is created in the metadata PWQ  402  for the address  401  (which is placed in the address field  404 ) with an associated valid tag  403  that is set to true. This new entry in the metadata PWQ  402  may overwrite an entry that has its valid tag  403  set to false. If no entry in the PWQ is invalid, a replacement scheme, such as a round robin or LRU replacement scheme, may be used to determine which entry acquires the new data in various embodiments. 
         [0020]      FIG. 5A  shows an embodiment of a system  500 A for counter-based entry invalidation for a metadata PWQ. System  500 A may be incorporated into cache  12  as is shown in  FIG. 1A . System  500 A includes a metadata PWQ  502  having a plurality of entries, each entry including a valid tag  503  and an address field  504 . Write address  501  and count signal  507  are received from the pipeline, such as pipeline  100  shown in  FIG. 1 . Count signal  507  may indicate, for example, each operation that checkpoints processing in the pipeline. Counter reset signal  508 , multiplexer  509 , and increment logic  511  are used to maintain counter  510 . The counter reset signal  508  may be triggered by writing of a new entry into the metadata PWQ  502 . Threshold  512  defines an upper bound for counter  510 , and invalidate logic  513  determines when counter  510  is equal to threshold  512 . In various embodiments, the threshold  512  may be a constant that is hardwired into the system  500 A, a constant that may be configurable by a user of the system  500 A, or may be determined based on the current state of the pipeline associated with the system  500 A; this is discussed in further detail below with respect to  FIGS. 6-8 . 
         [0021]    In some embodiments, a system for counter-based entry invalidation for a metadata PWQ may comprise a single counter  510  and associated logic, as is shown in  FIG. 5A  and discussed in further detail with respect to  FIG. 6 . In other embodiments, a system for counter-based entry invalidation for a metadata PWQ may comprise plurality of counters and associated logic, wherein the number of counters is equal to the number of entries in the metadata PWQ  502  and each counter acts to invalidate its single associated entry in the metadata PWQ  502 ; this is discussed in further detail with respect to  FIG. 5A-B  and  FIGS. 7-8 . An embodiment of a system  500 B for counter-based entry invalidation for a metadata PWQ including a plurality of counters  510 A-D is shown in  FIG. 5B . Each of counters  510 A-D is associated with a single entry in the metadata PWQ  502 . Each of counters  510 A-D has respective associated increment and reset logic, i.e., counter reset signal  508 , multiplexer  509 , and increment logic  511 , as are shown associated with counter  510  in  FIG. 5A . In some embodiments, the values of each of counters  510 A-D may be compared to a single threshold  512 ; in other embodiments, each of counters  510 A-D may have a separate respective threshold  512 .  FIG. 5B  is shown for illustrative purposes only; a system for counter-based entry invalidation for a metadata PWQ may comprise any appropriate number of entries in the metadata PWQ and associated counters. 
         [0022]      FIG. 6  shows an embodiment of a method  600  for counter-based entry invalidation for a metadata PWQ.  FIG. 6  is discussed with respect to  FIG. 5A . Method  600  may be applied in system  500 A with a single counter  510 . In various embodiments of method  600  of  FIG. 6 , the threshold  512  may be a constant that is hardwired into the system  500 A, or a constant that may be configurable by a user of the system  500 A. First, in block  601 , the counter  510  is set to zero by the counter reset signal  508 . Counter reset signal  508  may be triggered to reset the counter  510  to zero when a new entry is written into the metadata PWQ  502 ; the new entry may have a valid tag  503  that is set to valid, i.e., true. Then, in block  602 , the counter  510  is incremented by multiplexer  509  and increment logic  511  based on count signal  507 . In some embodiments, the count signal  507  may be triggered each time an operation checkpoints and leaves the pipeline, and the counter  510  is therefore incremented by multiplexer  509  and increment logic  511  each time an operation checkpoints and leaves the pipeline. Next, in block  603 , the invalidate logic  513  determines whether the value of counter  510  is equal to the threshold  512 . If the value of counter  510  is equal to the threshold  512 , the invalidate logic  513  triggers invalidate signal  514 , which invalidates all of the entries in the metadata PWQ  502  by setting each entry&#39;s respective valid tag  503  to, for example, false. Method  600  may be repeated, starting at block  601 , every time a new entry is written into the metadata PWQ  502 . Incrementing of the counter  510  and invalidation of entries, as described with respect to blocks  602  and  603 , may also be repeated as necessary. 
         [0023]      FIG. 7  shows another embodiment of a method  700  for counter-based entry invalidation for a metadata PWQ.  FIG. 7  is discussed with respect to  FIGS. 5A-B . Method  700  is applied in an embodiment of a system  500 B such as was shown in  FIG. 5B , including a plurality of counters  510 A-D, each with associated reset and increment logic (i.e., counter reset signal  508 , multiplexer  509 , and increment logic  511 ). Each of the counters  510 A-D is associated with a single respective entry in the metadata PWQ  502 , and a single threshold  512  is applied to each of the plurality of counters  510 A-D. In various embodiments of method  700  of  FIG. 7 , the threshold  512  may be a constant that is hardwired into the system  500 A-B, or a constant that may be configurable by a user of the system  500 A-B. First, in block  701 , when a new entry is written into the metadata PWQ  502 , the counter reset signal  508  for with the particular counter of counters  510 A-D that is associated with the new entry is triggered, resetting the counter that is associated with the new entry to zero. The new entry may have its valid tag  503  set to valid, i.e., true. Then, in block  702 , each of the plurality of counters  510 A-D is incremented simultaneously based on the count signal  507 . In some embodiments, the count signal  507  may be triggered each time an operation checkpoints and leaves the pipeline, and each counter  510 A-D of the plurality of counters is therefore incremented by its respective multiplexer  509  and increment logic  511  each time an operation checkpoints and leaves the pipeline. Next, in block  703 , the invalidate logic  513  determines whether the value of one or more of the plurality of counters  510 A-D is equal to the threshold  512 . If the value of any of the counters  510 A-D is equal to the threshold  512 , the invalidate logic  513  triggers invalidate signal  514 , which invalidates any entries in the metadata PWQ  502  that are associated with the one or more of the counters  510 A-D that were equal to the threshold  512 . Invalidation may be performed by setting the one or more entry&#39;s respective valid tag  503  to false. Method  700  may be repeated whenever a new entry is written into the metadata PWQ  502 . Incrementing of the counters  510 A-D and invalidation of associated entries, as described with respect to blocks  702  and  703 , may also be repeated as necessary. 
         [0024]      FIG. 8  shows another embodiment of a method  800  for counter-based entry invalidation for a metadata PWQ.  FIG. 8  is discussed with respect to  FIGS. 5A-5B . Method  800  is applied in an embodiment of a system  500 B such as was shown in  FIG. 5B , including a plurality of counters, such as counters  510 A-D, each with associated reset and increment logic (i.e., counter reset signal  508 , multiplexer  509 , and increment logic  511 ). Each of the counters  510 A-D is associated with a single respective entry in the metadata PWQ  502 , and the plurality of counters  510 A-D each have a separate respective threshold  512 . The plurality of thresholds  512  are determined based on the current state of the pipeline, such as pipeline  100  of  FIG. 1 , that is associated with metadata PWQ  502 . First, in block  801 , when a new address corresponding to an operation is written into an entry in the metadata PWQ  502 , the counter reset signal  508  for the particular counter of counters  510 A-D that is associated with the new entry is triggered, resetting the counter associated with the new entry to zero. Next, in block  802 , a new threshold  512  is determined for the counter that was reset in block  801 . In some embodiments, the threshold may be based on a total number of operations that are in the pipeline at the time of the write of the entry into the metadata PWQ. In other embodiments, the threshold may be based on a number of instances of the particular operation that are in the pipeline at the time of the write of an entry for the particular operation into the metadata PWQ. Flow then proceeds to block  803 , in which each of the counters  510 A-D are incremented simultaneously by each counter&#39;s respective multiplexer  509  and increment logic  511  based on the count signal  507 . In some embodiments, the count signal  507  may be triggered each time an operation checkpoints and leaves the pipeline, and each counter  510 A-D of the plurality of counters is therefore incremented by its respective multiplexer  509  and increment logic  511  each time an operation checkpoints and leaves the pipeline. Then, in block  804 , the invalidate logic  513  determines whether the value of any of the counters  510  of the plurality of counters is equal to the counter&#39;s respective threshold  512 . If the value of any of the counters  510 A-D is equal to the counter&#39;s respective threshold  512 , the invalidate logic  513  triggers invalidate signal  514 , which sets the valid tag  503  in any entries in the metadata PWQ  502  that are associated with the one or more counters  510  that were equal to their respective threshold  512  to false. Method  800  may be repeated whenever a new entry is written into the metadata PWQ  502 , and incrementing of the counters  510 A-D and invalidation of associated entries, as described with respect to blocks  803  and  804 , may also be repeated as necessary. 
         [0025]    As described above, embodiments can be embodied in the form of computer-implemented processes and apparatuses for practicing those processes. An embodiment may include a computer program product  900  as depicted in  FIG. 9  on a computer readable/usable medium  902  with computer program code logic  904  containing instructions embodied in tangible media as an article of manufacture. Exemplary articles of manufacture for computer readable/usable medium  902  may include floppy diskettes, CD-ROMs, hard drives, universal serial bus (USB) flash drives, or any other computer-readable storage medium, wherein, when the computer program code logic  904  is loaded into and executed by a computer, the computer becomes an apparatus for practicing the invention. Embodiments include computer program code logic  904 , for example, whether stored in a storage medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code logic  904  is loaded into and executed by a computer, the computer becomes an apparatus for practicing the invention. When implemented on a general-purpose microprocessor, the computer program code logic  904  segments configure the microprocessor to create specific logic circuits. 
         [0026]    Technical effects and benefits include prevention of incorrect blocking of writes into the metadata store by the metadata PWQ in a processor. 
         [0027]    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 one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0028]    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. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form 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 invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. 
         [0029]    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 one or more computer readable medium(s) having computer readable program code embodied thereon. 
         [0030]    Any combination of one or more computer readable medium(s) 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. 
         [0031]    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. 
         [0032]    Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing. 
         [0033]    Computer program code for carrying out operations for aspects of the present invention may be 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 program code may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;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&#39;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). 
         [0034]    Aspects of the present invention are described above with reference to flowchart illustrations and/or schematic 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. 
         [0035]    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. 
         [0036]    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. 
         [0037]    As described above, embodiments can be embodied in the form of computer-implemented processes and apparatuses for practicing those processes. In embodiments, the invention is embodied in computer program code executed by one or more network elements. Embodiments include a computer program product on a computer usable medium with computer program code logic containing instructions embodied in tangible media as an article of manufacture. Exemplary articles of manufacture for computer usable medium may include floppy diskettes, CD-ROMs, hard drives, universal serial bus (USB) flash drives, or any other computer-readable storage medium, wherein, when the computer program code logic is loaded into and executed by a computer, the computer becomes an apparatus for practicing the invention. Embodiments include computer program code logic, for example, whether stored in a storage medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code logic is loaded into and executed by a computer, the computer becomes an apparatus for practicing the invention. When implemented on a general-purpose microprocessor, the computer program code logic segments configure the microprocessor to create specific logic circuits. 
         [0038]    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 code, which comprises one or more executable instructions 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.