Abstract:
To efficiently transfer of data from a cache to a memory, it is desirable that more data corresponding to the same page in the memory be loaded in a line buffer. Writing data to a memory page that is not currently loaded in a row buffer requires closing an old page and opening a new page. Both operations consume energy and clock cycles and potentially delay more critical memory read requests. Hence it is desirable to have more than one write going to the same DRAM page to amortize the cost of opening and closing DRAM pages. A desirable approach is batch write backs to the same DRAM page by retaining modified blocks in the cache until a sufficient number of modified blocks belonging to the same memory page are ready for write backs.

Description:
BACKGROUND 
     Field 
     The embodiments are generally directed to managing memory of a computing device, and more specifically to cache memory management of a computing device. 
     Background Art 
     A computing device generally includes one or more processing units (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a general purpose GPU (GPGPU), an accelerated processing unit (APU), or the like), that access a memory. Memory accesses are also called memory events, and an example includes a write event (i.e., a memory access request to write data to main memory). The processing units may execute programs that result in accessing data in the memory. Some data is accessed more frequently than others. Access time of this data can be improved by using different levels of cache between the processor and the memory. 
     BRIEF SUMMARY OF EMBODIMENTS 
     It is desirable to improve access time of frequently accessed data by using a knowledge of the data access frequency, when transferring data between cache and the memory. 
     Certain embodiments include a method comprising storing data in a block in a cache. The cache may comprise a block set and may be coupled to a buffer. The buffer may be further coupled to a memory that may comprise multiple pages. The method may include evicting a block value from the block set to the buffer based on its priority status and its recentness of use, when there is not enough space to store the data in the block set. 
     Certain embodiments include a method comprising storing data in a first block in a cache. The cache may comprise a block set and may be coupled to a buffer. The buffer may be further coupled to a memory that may comprise multiple pages. For the memory page, a block count may be calculated to be the count of blocks in the cache that have dirty values corresponding to the page. A priority status may be assigned to each block that has a dirty value with an address corresponding to the page when the page block count exceeds a first threshold. A second block value may be copied to the buffer in response to assigning the priority status to the second block. The block count may be decreased for the page by one, after copying the second block value. The priority status from each block that otherwise has a priority status may be removed when the block count reduces below a second threshold. 
     Further features and advantages of the embodiments, as well as the structure and operation of various embodiments, are described in detail below with reference to the accompanying drawings. It is noted that the embodiments are not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES 
       The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the embodiments and, together with the description, further serve to explain the principles of the embodiments and to enable a person skilled in the pertinent art to make and use the embodiments. Various embodiments are described below with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. 
         FIG. 1  illustrates a system, according to an embodiment. 
         FIG. 2  illustrates cache blocks, according to an embodiment. 
         FIGS. 3-9  illustrate flowcharts depicting methods, according to embodiments. 
         FIG. 10  illustrates an example of a table of priority information of cache blocks, according to an embodiment. 
         FIG. 11  illustrates an example computer system in which embodiments may be implemented. 
     
    
    
     The embodiments will be described with reference to the accompanying drawings. Generally, the drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     In the detailed description that follows, references to “one embodiment,” “an embodiment,” “an example embodiment,” etc. indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. 
     The term “embodiments” does not require that all embodiments include the discussed feature, advantage or mode of operation. Alternate embodiments may be devised without departing from the scope of the disclosure, and well-known elements of the disclosure may not be described in detail or may be omitted so as not to obscure the relevant details. In addition, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. For example, 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,” “comprising,” “includes” and/or “including,” when used herein, 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. 
     Computing devices process data and provide many applications to users. Example computing devices include, but are not limited to, mobile phones, personal computers, workstations, and game consoles. Computing devices use a central processing unit (“CPU”) to process data. A CPU is a processor which carries out instructions of computer programs or applications. For example, a CPU carries out instructions by performing arithmetical, logical and input/output operations. In an embodiment, a CPU performs control instructions that include decision making code of a computer program or an application, and delegates processing to other processors in the electronic device, such as a graphics processing unit (“GPU”). 
     A GPU is a processor that is a specialized electronic circuit designed to rapidly process mathematically intensive applications (e.g., graphics) on electronic devices. The GPU has a highly parallel structure that is efficient for parallel processing of large blocks of data, such as mathematically intensive data common to computer graphics applications, images and videos. The GPU may receive data for processing from a CPU or generate data for processing from previously processed data and operations. In an embodiment, the GPU is a hardware-based processor that uses hardware to process data in parallel. 
     Due to advances in technology, a GPU also performs general purpose computing (also referred to as GPGPU computing). In the GPGPU computing, a GPU performs computations that traditionally were handled by a CPU. An accelerated processing unit (APU) includes at least the functions of a CPU and a GPU. The GPU can be a GPGPU. 
     In an embodiment, a GPU includes one or more compute units (CUs) that process data. A compute unit (CU) includes arithmetic logic units (ALUs) and other resources that process data on the GPU. Data can be processed in parallel within and across compute units. 
     In an embodiment, a control processor on a GPU schedules task processing on compute units. Tasks include computation instructions. Those computation instructions may access data stored in the memory system of a computing device and manipulate the accessed data. In an embodiment, the data may be stored in volatile or non-volatile memory. An example of volatile memory includes random access memory (RAM). Examples of RAM include dynamic random access memory (DRAM) and static random access memory (SRAM). Volatile memory typically stores data as long as the electronic device receives power. Examples of non-volatile memory include read-only memory (ROM), flash memory, ferroelectric RAM (F-RAM), hard disks, floppy disks, magnetic tape, optical discs, etc. Non-volatile memory retains its memory state when the electronic device loses power or is turned off. 
       FIG. 1  illustrates a system  100 , according to an embodiment. In one example, system  100  includes a memory  102 , a buffer  106 , a cache  108 , and a controller  110 . 
     Memory  102  may include a page  104 . Page  104  is for example a portion of memory  102 . According to an embodiment, memory  102  may include one page or multiple pages. Buffer  106  may include a data block  112 . Data block  112  is for example a portion of buffer  106 . According to an embodiment, buffer  106  may include one data block or multiple data blocks. 
     According to an embodiment, memory  102  may be a Dynamic Random Access Memory (DRAM). According to an embodiment, cache  108  may be a Last Level Cache (LLC). According to an embodiment, buffer  106  maybe a DRAM row buffer. 
     In an embodiment, buffer  106  is connected to memory  102  and cache  108 . Buffer  106  may be connected to cache  108  via connection  107 . In another embodiment, buffer  106  is not connected to cache  108  via a direct connection. Data may be transferred between buffer  106  and cache  108  via the connection between controller  110  and buffer  106  and the connection between controller  110  and cache  108 . 
     Cache  108  may include a block set or multiple block sets  114 , and each block set may include one or more data blocks  116 . Buffer  106  may be configured to buffer data from cache  108  for writing to one or more memory pages  104 . Buffer  106  may hold one or more data blocks  112 . 
     In one example, it may be desirable to have, at one time, a high number of data blocks  112  in buffer  106  that are written to a same memory page. This is referred to as high locality in buffer  106 . High locality may result in lower energy consumption in writing to memory  102  because writing multiple data blocks to a single memory page consumes less energy than writing the multiple data blocks to different memory pages. 
     Controller  110  is connected to buffer  106  and cache  108  according to an embodiment. Controller  110  may be configured to evict data block  116  from cache  108  to buffer  106 . For example, controller  110  may select data block  116 , and evict data block  116  by copying a value in data block  116  to buffer  106 . 
       FIG. 2  illustrates a cache, e.g., cache  108 , according to an embodiment. In this example, cache  108  may include cache blocks  212 ,  214 , and  216 . In another example, cache  108  may include block sets  218 , for example block set  0 , block set  1 , . . . , block set  63 . 
     In an embodiment, a block in cache  108  may correspond to a memory page in memory  102 , depending on an associativity of cache  108  with memory  102 . Associativity of a cache with a memory may show a correspondence between blocks in the cache to memory pages in the memory. In one example, each block in cache  108  may be associated with a corresponding memory page if cache  108  has full associativity with memory  102 . In other embodiments, a block in cache  108  may be associated with a corresponding one or more pages in memory  102  depending on associativity of cache  108  with memory  102 . In an embodiment, a set of blocks may be associated with a corresponding set of memory pages. 
     In one example, a block set  114  in cache  108  may include a Least Recently Used Block (LRU) and a Most Recently Used Block (MRU). An LRU may be a block that has new data written to it the longest time ago. An MRU may be a block that has new data written to it the shortest time ago. The blocks may be logically ordered from LRU in the most right hand side to MRU in a most left hand side. For illustration purposes  FIG. 2  shows logical ordering of the blocks, according to an embodiment. For example block  212  in block set  0  is the LRU block and block  214  is the MRU block of block set  0 . Physical ordering of the blocks in a set may not be in the recency of use order. 
       FIG. 3  illustrates a flowchart depicting a method  300 , according to an embodiment. In one example, method  300  is used to write data, with a memory page address, to a cache. Solely for illustrative purposes, the steps illustrated in  FIG. 3  will be described with reference to example system illustrated in  FIG. 1 . It is to be appreciated in some instances not all steps need be performed, nor performed in the order shown. 
     In step  302 , cache  108  receives new data. In step  304 , controller  110  determines which block set of multiple block sets  218  in cache  108  will be used for storing the data. For example, the block set or multiple block sets are selected based on the memory page address corresponding to the new data. 
       FIG. 4  illustrates a flowchart depicting a method  400 , according to an embodiment. In one example, method  400  is used to write data to a cache or to evict data from the cache. Solely for illustrative purposes, the steps illustrated in  FIG. 4  will be described with reference to example system illustrated in  FIG. 1 , cache  108  illustrated in  FIG. 2 , and method  300  illustrated in  FIG. 3 . In an embodiment, controller  110  may perform some or all of the steps of method  400 . It is to be appreciated in some instances not all steps need be performed, nor performed in the order shown. 
     According to an embodiment, when there is new data ready to be written to cache  108 , at step  404  it is determined whether there is space available in a block set in block sets  218  for storing the new data. The block set for storing the new data may be determined in step  304 . If at step  404  it is determined space is available in the block set, at step  408  the new data may be written to one or more available data blocks in the block set and mark the blocks as dirty. For example if data is written to block set  0  in cache  108 , the new data may be written to block  216 , and block  216  is marked as dirty. In an embodiment, block  216  may remain dirty until the data in block  216  is evicted to buffer  106 . Evicting data may be copying or conveying the data to buffer  106 , for example. Evicting a data block may refer to evicting the data stored in the block. In an embodiment, if the new data already exists in a data block of cache  108 , the new data is overwritten the existing data block without requiring the eviction of another block. 
     According to an embodiment, if no space is available for writing the new data in the block set determined in step  304 , at step  406  at least one block is evicted from the block set. In an embodiment as many data blocks as necessary may be evicted so that there is space for storing the new data. After evicting as many blocks as necessary, the new data may be written in the available blocks and marked as dirty in step  408 . 
     In an embodiment, method  400  at step  410  may order the blocks in the block set such that the blocks that have new value written to them in step  408 , are ordered as the most recently used blocks, or in the MRU side of the block set. For example, referring to  FIG. 2 , if new data value is written to block  216  in block set  0  of cache  108 , method  400  at step  410  orders the blocks in block set  0  such that block  216  is the Most Recent Used (MRU) block of block set  0 . 
       FIG. 5  illustrates a flowchart depicting a method  500 , according to an embodiment. In one example, method  500  is used to determine a priority of a block in a cache. Solely for illustrative purposes, the steps illustrated in  FIG. 5  will be described with reference to example system illustrated in  FIG. 1  and cache  108  illustrated in  FIG. 2 . In an embodiment, controller  110  may perform some or all of the steps of method  500 . It is to be appreciated in some instances not all steps need be performed, nor performed in the order shown. 
     In an embodiment, method  500  determines priority for each memory page of memory  102 . As an example, memory page  104  is used to describe method  500 . Method  500  may be used for determining priority with respect to other memory pages in memory  102 . 
     In an embodiment, at step  503  a count of dirty blocks in cache  108  that have value with address corresponding to memory page  104  is determined. At step  504 , a determination is made whether the count is greater than a first threshold. If the count is greater than the first threshold, at step  506  priority is assigned to all of the blocks in cache  108  that have value with address corresponding to memory page  104 . 
     In an embodiment, if the count is less than the first threshold, at step  508  a determination is made whether the count is less than a second threshold. If the count is not less than the second threshold,  500  ends at step  514 . 
     In an embodiment, if the count is less than the second threshold, at step  510 , a determination is made whether the block or blocks that have data corresponding to memory page  104  are already assigned priority. If the blocks are not assigned priority the method may end at step  514 . In an embodiment, if the blocks having data corresponding to memory page  104  are assigned priority, at step  512  priority is removed from all of the blocks having value with address corresponding memory page  104 . 
     In an embodiment, the first and second thresholds are predetermined. In an embodiment, either or both of the first and second thresholds may be dynamically determined for each operation of method  500 . In another embodiment, the second threshold may be zero. 
       FIG. 6  illustrates a flowchart depicting a method  600 , according to an embodiment. In one example, method  600  is used to evict from cache  108  to buffer  106 . Solely for illustrative purposes, the steps illustrated in  FIG. 6  will be described with reference to example system illustrated in  FIG. 1  and cache  108  illustrated in  FIG. 2 . In an embodiment, controller  110  may perform some or all of the steps of method  600 . It is to be appreciated in some instances not all steps need be performed, nor performed in the order shown. 
     In an embodiment, at step  604  a determination is made whether there is any block with priority status in a least recently used blocks sub-set of a block set in block sets  218 . For example the least recently used blocks sub-set may be the N blocks in the block set that were used the longest time ago, wherein N is an integer. In an embodiment, N may be dynamically determined each time method  600  is used. In an embodiment, N is predetermined. 
     If there is a block with priority in the least recently used blocks sub-set, at step  606  a least recently used block with priority in the block sub-set is evicted. The least recently used block with priority may be a block that has new data written to it the longest time ago and is assigned priority. 
     If there is no block with priority in the least recently used blocks sub-set, at step  608  the least recently used block in the block sub-set, regardless of priority, may be evicted. The least recently used block may be the block that has new data written to it the longest time ago. 
       FIG. 7  illustrates a flowchart depicting a method  700 , according to an embodiment. In one example, method  700  is used to store data in a cache. Solely for illustrative purposes, the steps illustrated in  FIG. 7  will be described with reference to example system illustrated in  FIG. 1 , and cache  108  illustrated in  FIG. 2 . In an embodiment, controller  110  may perform some or all of the steps of method  700 . It is to be appreciated in some instances not all steps need be performed, nor performed in the order shown. 
     In an embodiment, at step  704  new data, corresponding to a memory page in memory  102 , is stored in a block in cache  108  and the block is marked as dirty. For example new data, corresponding to memory page  104 , is written in block  216  in cache  108  and block  216  is marked as dirty. In an embodiment, block  216  may remain dirty until the data in block  216  is evicted to buffer  106 , or the data block is otherwise marked as clean. 
     In an embodiment, at step  706  a count of dirty blocks in cache  108  that have value with address corresponding to the memory page of step  704  is determined. In an embodiment, at step  708  a determination is made whether the block count for the memory page of step  704  is greater than a third threshold. In an embodiment, if the count is greater than the third threshold, at step  710  a priority status is assigned to all the dirty blocks containing value with address corresponding to the memory page of step  704 . In an embodiment, if the count is not greater than the third threshold,  700  ends at step  712 . 
       FIG. 8  illustrates a flowchart depicting a method  800 , according to an embodiment. In one example, method  800  is used to copy a block value from a cache to a buffer. Solely for illustrative purposes, the steps illustrated in  FIG. 8  will be described with reference to example system illustrated in  FIG. 1 , and example cache  108  illustrated in  FIG. 2 . In an embodiment, controller  110  may perform some or all of the steps of method  800 . It is to be appreciated in some instances not all steps need be performed, nor performed in the order shown. 
     In embodiments, method  800  copies a block value from cache  108  to buffer  106 , such that there will be high locality in the buffer. According to an embodiment, at step  804  a determination is made whether there is bandwidth available on a connection  107  between cache  108  and buffer  106 . In example embodiments, transmitting a block value between cache  108  to buffer  102  consumes bandwidth on connection  107 . In an embodiment, a block value may be transmitted in addition to current data being transmitted on connection  107 , when there is enough bandwidth available for the block value. 
     In an embodiment, if there is not enough bandwidth available for transmitting a cache block value on connection  107 ,  800  ends at step  814 . In an embodiment, if there is enough bandwidth available for transmitting a block value on connection  107 , at step  806  a determination is made whether there is a block with priority status in cache  108 . In an embodiment, if at step  806  a determination is made that there is no block with priority status in cache  108 ,  800  ends at step  814 . 
     In embodiments, buffer  106  is not connected to cache  108  via a direct connection  107 , as described with respect to  FIG. 1 . Steps of method  800  that use connection  107  may be performed using the connection between controller  110  and buffer  106  and the connection between controller  110  and cache  108 . 
     In an embodiment, if there is a block with priority status in cache  108 , at step  808  value of a block with priority status is transmitted to the buffer  106 . In an embodiment at step  808  value of a least recently used block with priority status is transmitted to buffer  106 . In an embodiment, at step  808  value of a block with priority status within a first number of least recently used blocks, is transmitted to buffer  106 . In an embodiment, a block is within a first number of least recently used blocks, when the block is among the first number of blocks that have data written to them the longest time ago. 
     In an embodiment the first number is predetermined. In another embodiment the first number is dynamically determined before executing method  800 . 
     In an embodiment at step  810  a determination is made whether the block count for the corresponding memory page to the copied block is less than a fourth threshold. In an embodiment, if the block count is not less than the fourth threshold,  800  ends at step  814 . In an embodiment, if the block count is less than the fourth threshold, at step  812  the priority status from all the blocks corresponding to the memory page of step  810  is removed. 
     In an embodiment, the third and fourth thresholds are predetermined. In another embodiment, the third and fourth threshold may be dynamically determined for each operation of method  800 . In an embodiment, the fourth threshold may be zero. 
       FIG. 9  illustrates a flowchart depicting a method  900 , according to an embodiment. In one example, method  900  is used to delete or clean a block in a cache. Solely for illustrative purposes, the steps illustrated in  FIG. 9  will be described with reference to example system illustrated in  FIG. 1 . In an embodiment, controller  110  may perform some or all of the steps of method  900 . It is to be appreciated in some instances not all steps need be performed, nor performed in the order shown. 
     In an embodiment, at step  904 , when a block value is copied to buffer  106 , the block is marked as clean. In embodiments, when a block is marked as clean it is not dirty any more. 
     In an embodiment, at step  906  a determination is made whether the cleaned block at step  904  is within a second number of least recently used blocks within a block set that includes the cleaned block. In an embodiment, if the block is not within the second number of least recently used blocks,  900  ends at step  910 . 
     In an embodiment, if the cleaned block is within the second number of least recently used blocks, at step  908  the cleaned block value is deleted and the block becomes available for storing new value. 
     In an embodiment the second number is predetermined. In another embodiment, the second number is dynamically determined before executing method  900 . In an embodiment, the second number is zero. 
     Embodiments may use approximations of least recently used blocks, such as “Pseudo Least Recently Used” (pLRU) instead of least recently used blocks described above. 
       FIG. 10  illustrates a table according to an embodiment. In this example, table  1000  is used to store priority information for all cache blocks having value with address corresponding to each memory page. Solely for illustrative purposes, table  1000  will be described with reference to example system illustrated in  FIG. 1 . 
     According to an embodiment, table  1000  may include a row corresponding to each memory page in memory  100 . In an embodiment table  1000  includes a memory page address column, a dirty block count column, and a priority bit column. According to an embodiment, a first column in a row includes an address of a memory page, a second column in the row includes a count of all dirty blocks having value with address corresponding to the memory page, and a third column in the row includes a priority bit. According to an embodiment, when methods  500 ,  700 , or  800  determine priority for all the blocks having dirty value with address corresponding to a memory page, the priority bit of a row corresponding to the memory page in table  1000  is set to “1” to show priority. 
     For example, in table  1000  page address  1002  indicates memory page address  0 . Dirty block count  1004  indicates that there are 16 dirty blocks having value with address corresponding to memory page address  0 . And “1” in priority bit  1006  indicates that method  500 ,  700 , or  800  has determined that all the blocks having value with address corresponding to memory page address  0  have priority. 
     Various aspects of the disclosure can be implemented by software, firmware, hardware, or a combination thereof.  FIG. 11  illustrates an example computer system  1100  in which some embodiments, or portions thereof, can be implemented as computer-readable code. For example, the methods  300 - 900 , of  FIGS. 3 through 9  can be implemented in system  1100 . Various embodiments are described in terms of the example computer system  1100 . After reading this description, it will become apparent to a person skilled in the relevant art how to implement the embodiments using other computer systems and/or computer architectures. 
     Computer system  1100  includes one or more processors, such as processor  1104 . Processor  1104  can be a special purpose or a general purpose processor. 
     Computer system  1100  also includes a main memory  1108 , such as random access memory (RAM) such as memory  102  of  FIG. 1 , and may also include a secondary memory  1110 . Secondary memory  1110  may include, for example, a hard disk drive  1112 , a removable storage drive  1114 , and/or a memory stick. Removable storage drive  1114  may comprise a floppy disk drive, a magnetic tape drive, an optical disk drive, a flash memory, or the like. The removable storage drive  1114  reads from and/or writes to a removable storage unit  1118  in a well-known manner. Removable storage unit  1118  may comprise a floppy disk, magnetic tape, optical disk, etc. that is read by and written to by removable storage drive  1114 . As will be appreciated by persons skilled in the relevant art(s), removable storage unit  1118  includes a computer usable storage medium having stored therein computer software and/or data. 
     In alternative implementations, secondary memory  1110  may include other similar means for allowing computer programs or other instructions to be loaded into computer system  1100 . Such means may include, for example, a removable storage unit  1122  and an interface  1120 . Examples of such means may include a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as an EPROM, or PROM) and associated socket, and other removable storage units  1122  and interfaces  1120  that allow software and data to be transferred from the removable storage unit  1122  to computer system  1100 . 
     Computer system  1100  may also include a communications interface  1124 . Communications interface  1124  allows software and data to be transferred between computer system  1100  and external devices. Communications interface  1124  may include a modem, a network interface (such as an Ethernet card), a communications port, a PCMCIA slot and card, or the like. Software and data transferred via communications interface  1124  are in the form of signals that may be electronic, electromagnetic, optical, or other signals capable of being received by communications interface  1124 . These signals are provided to communications interface  1124  via a communications path  1126 . Communications path  1126  carries signals and may be implemented using wire or cable, fiber optics, a phone line, a cellular phone link, an RF link or other communications channels. 
     In this document, the terms “computer program medium” and “computer usable medium” are used to generally refer to media such as removable storage unit  1118 , removable storage unit  1122 , and a hard disk installed in hard disk drive  1112 . Signals carried over communications path  1126  can also embody the logic described herein. Computer program medium and computer usable medium can also refer to memories, such as main memory  1108  and secondary memory  1110 , which can be memory semiconductors (e.g. DRAMs, etc.). These computer program products are means for providing software to computer system  1100 . 
     Computer programs (also called computer control logic) are stored in main memory  1108  and/or secondary memory  1110 . Computer programs may also be received via communications interface  1124 . Such computer programs, when executed, enable computer system  1100  to implement the embodiments as discussed herein. In particular, the computer programs, when executed, enable processor  1104  to implement the disclosed processes, such as the steps in the method  300  of  FIG. 3 , method  400  of  FIG. 4 , method  500  of  FIG. 5 , method  600  of  FIG. 6 , method  700  of  FIG. 7 , method  800  of  FIG. 8 , or method  900  of  FIG. 9 , as discussed above. Accordingly, such computer programs represent controllers of the computer system  1100 . Where the embodiments are implemented using software, the software may be stored in a computer program product and loaded into computer system  1100  using removable storage drive  1114 , interface  1120 , hard drive  1112  or communications interface  1127 . This can be accomplished, for example, through the use of general-programming languages (such as C or C++). The computer program code can be disposed in any known computer-readable medium including semiconductor, magnetic disk, or optical disk (such as, CD-ROM, DVD-ROM). As such, the code can be transmitted over communication networks including the Internet and internets. It is understood that the functions accomplished and/or structure provided by the systems and techniques described above can be represented in a core (such as a processing-unit core) that is embodied in program code and may be transformed to hardware as part of the production of integrated circuits. This can be accomplished, for example, through the use of hardware-description languages (HDL) including Verilog HDL, VHDL, Altera HDL (AHDL) and so on, or other available programming and/or schematic-capture tools (such as, circuit-capture tools). 
     Embodiments are also directed to computer program products comprising software stored on any computer useable medium. Such software, when executed in one or more data processing device, causes a data processing device(s) to operate as described herein. Embodiments employ any computer useable or readable medium, known now or in the future. Examples of computer useable mediums include, but are not limited to, primary storage devices (e.g., any type of random access memory), secondary storage devices (e.g., hard drives, floppy disks, CD ROMS, ZIP disks, tapes, magnetic storage devices, optical storage devices, MEMS, nanotechnological storage device, etc.), and communication mediums (e.g., wired and wireless communications networks, local area networks, wide area networks, intranets, etc.). 
     It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more but not all exemplary embodiments as contemplated by the inventor(s), and thus, are not intended to limit the disclosure and the appended claims in any way. 
     The disclosure has been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed. 
     The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance. 
     The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.