Patent Publication Number: US-7913100-B2

Title: Opportunistic initiation of data traffic

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to trafficking data between a device and a target resource. More particularly, some embodiments of the invention initiate data traffic based on an indication of a power condition in a system resource. 
     2. Background Art 
     In a data trafficking system, efficient data trafficking often depends on how system components operate with respect to one another. For example, a data trafficking device trafficking data with a target resource in such a system may have to coordinate with various system resources, such as the target resource itself and/or interface resources which facilitate trafficking data between the target resource and the data trafficking device. Some systems include resources which can variously operate in different power states, where a given power state is associated with a particular capacity to facilitate data trafficking. For example, a particular system resource may be able to operate either in an active power state associated with its full capacity to facilitate data trafficking, or in an inactive power state associated with a lower capacity to facilitate data trafficking. Generally, higher capacities to facilitate data trafficking correspond to power states of system resources which consume more system power. 
     Complex systems may have one or more data trafficking devices variously trafficking data at any given time. As the scale of data trafficking in these systems increases, there is an increased likelihood that at any given time, a particular system resource will be required to operate in an active power state to facilitate some data trafficking initiated by a particular data trafficking device. Over time, this increased likelihood results in a system resource having to more frequently remain in an active state, operating at higher rates of power consumption for longer periods of time. This increased likelihood also results in system resources having to come out of inactive or power managed states after shorter periods of lowered power consumption. Also, this increased likelihood results in system resources having to more frequently switch between higher and lower power states associated with higher and lower capacities to facilitate data trafficking. Consequently, system resources which can variously operate in different power states are more likely to cause increased system power consumption and inefficiently switch power states as the amount of data trafficking in the system increases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various embodiments of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which: 
         FIG. 1  is a block diagram illustrating a data trafficking system according to an embodiment of the invention. 
         FIG. 2  is a flow diagram illustrating an algorithm according to one embodiment of the invention. 
         FIGS. 3A-3D  are block diagrams illustrating data trafficking systems according to embodiments of the invention. 
         FIG. 4  is a timing diagram illustrating data traffic in a system implementing an embodiment of the invention. 
         FIG. 5  is a flow diagram illustrating an algorithm according to one embodiment of the invention. 
         FIG. 6  is a flow diagram illustrating an algorithm according to one embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a data trafficking system  100  according to an embodiment of the invention. Data trafficking system  100  may, for example, be variously implemented on one of a server platform (e.g. in a blade server), desktop computer platform (e.g. on a motherboard) and a mobile platform. System  100  includes a data trafficking device  110  configured for communication with target resource  150  via interface resource  140 . Data trafficking device  110  may include any of a variety of devices for receiving and/or sending data in system  100 . For example, data trafficking device  110  may be any of a variety of devices for conveying information to and/or from system  100  including, but not limited to a visual display device, a keyboard, a mouse, a speaker, wireless network device, TV tuner, and a modem. Data trafficking device  110  may communicate with other devices external to system  100 , e.g. via a wireless transceiver. 
     Interface resource  140  may include any resource supporting the trafficking of data between data trafficking device  110  and a target resource. An interface resource  140  may include one or more interface elements. For example, interface resource  140  may have any of a variety of combinations of hardware and/or software interface elements including, but not limited to, a bus, a bridge, a controller, a reference clock mechanism such as a clock tree to synchronize other interface elements, and circuitry supporting an interface specification—e.g. Desktop Management Interface (DMI) Specification, Version 2.0s, Desktop Management Taskforce, Inc., Jun. 24, 1998. 
     Target resource  150  may include any resource to facilitate the storing and/or processing (e.g. analyzing or converting) of data sent to and/or received from a data trafficking via the interface resource  140 . The target resource  150  may include one or more target resource elements. For example, the target resource  150  may include any of a variety of combinations of memory elements including, but not limited to read-only memory (ROM), random access memory (RAM) such as static RAM (SRAM) and dynamic RAM (DRAM), and non-volatile memory such as flash memory. Additionally or alternatively, target resource  150  may itself include a data trafficking device similar to data trafficking device  110 . Target resource  150  may further include clock timing, processing, power and/or other elements enabling the operation of target resource  150 . 
     Interface resource  140  and target resource  150  may be referred to more generally as system resources, at least insofar as they are resources of system  100  of which a device such as data trafficking device  110  may avail for facilitating data traffic. In various embodiments of the invention, a given system resource may at a particular time have a particular power condition. A system resource or an element thereof may at various times operate in different power states. For example, a system resource such as interface resource  140  or target resource  150  may be able to change between (1) operating in an active (e.g. high voltage level and/or high frequency) state associated with a particular level of power consumption and a particular capacity to facilitate data trafficking, and (2) operating in a power managed (e.g. low voltage level and/or low frequency) state associated with a lower level of power consumption and a different capacity to facilitate data trafficking. A power condition of a system resource may include a power state of the system resource (and/or an element thereof). Alternatively or in addition, a power condition of the system resource may include a transition (and/or a rate of transition) in a power state of the system resource (and/or an element thereof). Alternatively or in addition, a power condition of a system resource may include an existing power state (or transition or rate of transition thereof) and/or an expected future power state (or transition or rate of transition thereof). 
     In various embodiments of the invention, data trafficking device  110  may initiate traffic data based at least in part on a power condition of a system resource. By way of illustration, a power condition of target resource  150  may result in an opportunity for data trafficking device  110  to initiate a trafficking of data in system  100 . At a particular time, for example, a data traffic  145  to and/or from target resource  150  may require target resource  150  to include an active power state required for such data traffic  145 . As will be discussed hereafter, data traffic  145  may result in various different direct or indirect indications may be generated in system  100  which indicate a power condition of a system resource (e.g. the power state of data source  150 ). 
     In the case of system  100 , an indication  135  is received by detecting unit  130  of data trafficking device  110 . Detecting unit  130  may, for example, include any of a variety of current, voltage, or power sensors, data processing elements or similar means for detecting the indication  135  as indicating a power condition of a system resource. In an embodiment of the invention, the indication  135  of a power condition of a system resource may be independent of any data traffic of data trafficking device  110 . For example, indication  135  may be independent of data trafficking device  110  sending a communication to initiate particular data traffic. By way of illustration, indication  135  may result from data traffic of another data trafficking device (not shown) or from a predictable operation of system resources which is not in response to any data traffic of data trafficking device  110 . According to an embodiment of the invention, detecting unit  130  may direct initiating unit  120  of data trafficking device  110  to initiate some data traffic in response to the indication  135 . For example, initiating unit  120  may initiate data traffic  125  of data trafficking device  110 , which may include sending data from (and/or receiving data at) data trafficking device  110 . 
     Initiating data traffic refers to performing some action which will, either directly or indirectly, result in some communication of data by a data trafficking device. For example, initiating data traffic  125  may include sending a signal from data trafficking device  110  to a system resource or to another data trafficking device, wherein the signal indicates a need for data to be trafficked. Additionally or alternatively, initiating data traffic may include data trafficking device  110  performing actions internal to itself which may induce the sending of data to and/or from data trafficking device  110 . 
     For example, data trafficking device  110  may include an input data buffer (not shown) to be automatically written to by target resource  150  once the amount of data stored in the input data buffer is below a minimum threshold. In response to detecting an indication  135  that a particular power condition allows target resource  150  to perform writes to the input data buffer, data trafficking device  110  may initiate an automatic write to the input data buffer by debuffering data from the input data buffer until the amount of data stored in the data buffer is below the minimum threshold. 
     Similarly, data trafficking device  110  may include an output data buffer (not shown) to write data to target resource  150  once the amount of data stored in the output data buffer is above a maximum threshold. In response to detecting an indication  135  that a particular power condition allows target resource  150  to receive buffered data, data trafficking device  110  may initiate an automatic write  125  to the target resource  150  by buffering data until the amount of data stored in the output data buffer is above the maximum threshold. 
     The initiated data traffic may include the sending of data to and/or from a particular target resource, an indication of whose power condition has been detected by the data trafficking device  110 . Alternatively or in addition, the initiated data traffic may include sending data to another target resource, e.g. via an interface resources separate from a particular interface resource by which the data trafficking device  110  received an indication of a power condition of a system resource. 
     In various embodiments of the invention, the opportunistic initiation of data traffic (e.g. initiating data traffic to take advantage of a system resource power condition) may further be in response to determining a data exchange which justifies the initiating of data traffic. For example, a particular initiating of data traffic may be based on a relative benefit of initiating the data traffic in relation to a performance overhead associated with the initiated of data traffic. A data exchange which justifies the initiating of data traffic may be determined based on any of a variety of combinations of factors including, but not limited to, a status of the data trafficking device (e.g., available download/upload rates and/or existing processing load), a condition of one or more system resources (e.g. an expected communication rate of a system resource or an expected delay in acquiring authorization for data traffic), and an amount of data to be exchanged and a type of data to be exchanged (e.g. whether some minimum amount of the data can be exchanged in the data traffic) 
       FIG. 2  illustrates an algorithm  200  for a method implementing one embodiment of the invention. Algorithm  200  may be implemented, for example, by a data trafficking device such as data trafficking device  110 . The algorithm  200  begins at  210 , wherein a data trafficking device is configured to traffic data with a target resource via an interface resource. At  220 , the data trafficking device may detect an indication of a system resource power condition. In one embodiment, the system resource power condition may include a condition of an interface resource and/or a target resource. As discussed previously, the indication detected by the data trafficking device may be independent of any data traffic of the data trafficking device. 
     At  230 , the data trafficking device may opportunistically initiate data traffic in response to the detecting of the indication at  220 . Opportunistically initiating data traffic refers to the data trafficking device taking advantage of the indicated power condition in trafficking data. For example, the data trafficking device may avail of an already existing opportunity to exploit the indicated power condition by trafficking data with a target resource such as target resource  150 . As discussed below, the opportunistic initiating of data traffic at  230  may further be in response to other conditions of the data trafficking device and/or system resources. At  240 , the algorithm  200  ends with the data trafficking device having initiated data traffic without having to invoke a particular power condition which may otherwise have to be invoked for such a trafficking of data. 
       FIGS. 3A-3D  illustrate systems  300 ,  320 ,  340  and  360 , each capable of variously implementing opportunistic data trafficking according to embodiments of the invention.  FIG. 3A  illustrates a system  320  wherein Data Trafficker  1   302  and a Data Trafficker  2   306  each communicate with at least memory  310  via an interface  312 . Similarly,  FIG. 3B  illustrates a system  320  wherein Data Trafficker  1   322  and a Data Trafficker  2   326  each communicate with at least memory  330  via an interface  332 . Similarly,  FIG. 3C  illustrates a system  340  wherein Data Trafficker  1   342  and a Data Trafficker  2   346  each communicate with at least memory  350  via an interface  352 . Lastly,  FIG. 3D  illustrates a system  360  wherein Data Trafficker  1   362  and a Data Trafficker  2   366  each communicate with at least memory  370  via an interface  372 . Although exemplary embodiments of the invention are described herein with reference to data trafficking devices trafficking data with memory devices, the invention may be extended to also apply to data trafficking devices trafficking data with other system resources such as another data trafficking device. In various embodiments of the invention, a data trafficker in one of systems  300 ,  320 ,  340  and  360  may variously include characteristics and elements discussed above with reference to data trafficking device  110 . Embodiments of the invention are described herein with reference to data traffickers  302 ,  322 ,  342  and  362  respectively initiating data traffic  314 ,  334 ,  344  and  374  in response to detecting respective indications  304 ,  324 ,  356  and  364  of power conditions of system resources. 
     In the example of system  300 , Data Trafficker  1   302  opportunistically initiates data traffic  314  in response to detecting an indication of a power condition associated with memory  310 . For example, data traffic  308  of Data Trafficker  2   306  via interface  312  may require that memory  310  includes a power state which is also conducive to Data Trafficker  1   302  initiating a different data traffic  314 . The opportunity to avail of the power state of memory  310  may be made know to Data Trafficker  1   302 , for example, by an indication  304  of a power condition including the power state of memory  310 . In an embodiment of the invention, an indication of the power condition of a system resource may include an explicit indication generated by the system resource itself. For example, target resource  310  may explicitly send a signal  304  (e.g. unicast, multicast or broadcast) to indicate that it is in a particular power condition which may facilitate data traffic from Data Trafficker  1   302 . Upon detecting the indication  304  of a power condition of memory  310 , Data Trafficker  1   302  may opportunistically initiate a trafficking of data  314  which avails of the power state of memory  310  which is included in the power condition indicated by signal  304 . The invention is not limited as to the particular direction of the data traffic which is initiated. 
     Alternatively or in addition, an indication of a power condition may include an indication generated by a system resource other than a target resource which is a target of the initiated data traffic. For example, an indication of a power condition may include an indication generated by an interface resource such as another data trafficker. In the case of  FIG. 3B , Data traffic  328  between Data Trafficker  2   326  and memory  330  via interface  332  may mean that a power condition exists of which Data Trafficker  1   322  may take advantage by initiating its own data traffic  334 . For example, such a power condition may include a power state and/or a change in a power state in one or more system resources which may be conducive to data trafficking by Data Trafficker  1   322 . In various embodiments, Data Trafficker  2   326  may directly or indirectly send an indication  324  to Data Trafficker  1   322  (e.g. via a path separate from interface  332 ) indicating at least in part that data traffic  328  is taking place. Alternatively, indication  324  may indicate at least in part that data traffic  328  is expected to take place at some future time. Indication  324  may indicate to Data Trafficker  1   322  that data traffic  328  has resulted in a power condition of a system resource of which Data Trafficker  1  can avail. In response to the detecting of indication  324 , Data Trafficker  1   322  may initiate data traffic  334  which takes advantage of the power condition indicated by indication  324 . 
     Alternatively or in addition, an indication of a power condition may include an indication generated by an interface resource. In the case of  FIG. 3C , interface  352  may include an interface agent  354  though which data trafficking requests of Data Trafficker  1   322  and Data Trafficker  2   326  are handled. For example, interface agent  354  may variously perform one or more authentication, authorization, connection, coordination or similar services in aid of a given data trafficker trafficking data with a system resource such as memory  330 . Data traffic  348  between Data Trafficker  2   346  and memory  350  via interface agent  354  may mean that a power condition exists of which Data Trafficker  1   342  may avail in initiating its own data traffic  344 . For example, such a power condition may include an active power condition in a chip-to-chip interconnect of which Data Trafficker  1   342  may also avail. 
     In various embodiments, interface agent  354  may directly or indirectly send a indication  356  (e.g. unicast, multicast or broadcast) to Data Trafficker  1   342  indicating at least in part that data traffic  348  is taking place. Alternatively, indication  356  may indicate at least in part that data traffic  348  is expected to take place at some future time. Data Trafficker  1   342  may detect from indication  356  that a power condition may be exploited by initiating data traffic  344 . In response to the detecting of indication  356 , Data Trafficker  1   342  may initiate data traffic  344  which takes advantage of the power condition indicated by indication  356 . Alternatively or in addition, an indication of the power condition of a system resource may include an indication which is incidentally generated in the course of operation of the system. An incidental indication of the power condition of a system resource may include an indication which the data trafficking device listens for, polls, requests or otherwise actively acquires from one or more system resources. In the exemplary case of  FIG. 3D , interface  372  may include a bus, chip-to-chip interconnect or similar element which enters an active power state in order facilitate data traffic  368  of Data Trafficker  2   366 . Alternatively, such an element may enter an active state in the course of its regular operation, e.g. independent of any need to traffic data. 
     In an embodiment of the invention, Data Trafficker  1   362  actively looks to detect the occurrence  364  of interface  372  including this active state of an interface element. In another embodiment, an occurrence  364  may represent Data Trafficker  1   362  simply detecting that a particular type of data traffic is being carried in interface  372 . For the purposes of practicing certain embodiments of the invention, occurrence  364  represents some indication detected by Data Trafficker  1   362  of a power state of a system resource of which Data Trafficker  1   362  may avail in initiating data traffic  374 . In response to detecting the occurrence  364 , Data Trafficker  1   362  initiates data traffic  374  which takes advantage of the power condition indicated by indication  364 . 
       FIG. 4  is a timing diagram  400  including a timing sequence  410  for illustrating the behavior of data trafficking devices when they do not implement an embodiment of the invention and timing sequence  420  for illustrating the behavior of data trafficking devices when they do implement a particular embodiment of the invention. As indicated in the legend of  FIG. 4 , timing diagram  400  represents activity in a system having at least three devices (Device  1 , Device  2  and Device  3 ) variously trafficking data as input and/or output (I/O) to system resources including Memory. In the case of timing sequence  410 , each of Device  1 , Device  2  and Device  3  initiates its respective data traffic independent of any indication of a system resource power condition which is not an indication resulting from its own data traffic. 
     As a result of Device  1 , Device  2  and Device  3  not initiating data traffic in order to avail of already existing power conditions, the data traffic of any one device, which may have resulted in a particular power condition, will not, in and of itself, cause another device to initiate its own data traffic in response to detecting an indication of that resulting power condition. Opportunities to initiate data traffic are thereby missed, and consequently, the I/O of a device not implementing an embodiment of the invention may, over time, tend to be more spread out with respect to the I/O of other devices. As the I/O of devices become more spread out over time, system resources including the represented Memory may have to remain in various active power states for longer periods of time, e.g. time period  412 . Similarly, system resources may have to come out of power managed states sooner, as data traffic is initiated which might otherwise have been trafficked in a previous active power state. 
     By way of illustration, timing sequence  410  includes I/O traffic  415  of Device  2  which has come after an opportunity to traffic data with Memory. As a result of Device  2  not initiating data traffic in response to an already existing power condition (e.g. the active power state of Memory) I/O traffic  415  cannot traffic data with Memory. As a result, system resources may have to remain in an active state for a longer period of time in order to find an alternative way to handle I/O traffic  415 , or Memory must be brought out of a power managed state sooner in order to facilitate I/O traffic  415 . As a result, system resources are also more likely to remain in high power consumption states and/or inefficiently switch between various active and power managed power states, as there is no coordination in the initiation of data traffic of Device  1 , Device  2  and Device  3 . 
     By contrast, timing sequence  420  illustrates each of Device  1 , Device  2  and Device  3  initiating respective data traffic in response to system resource power conditions which are independent of its own data traffic. As demonstrated by time period  422 , I/O traffic of Device  1  has resulted in a system resource power condition which Device  3  may also exploit by initiating its own I/O. In response to detecting an indication of this power condition, Device  3  may initiate its own I/O traffic more quickly than it would have otherwise if Device  3  were not implementing an embodiment of the invention. As a result, I/O traffic from one device implementing an embodiment of the invention is more likely to result in a sequential initiating of I/O traffic from similar devices, resulting in tighter grouping of I/O traffic over time. This tighter grouping allows system resources to variously change to respective power managed states earlier than they might otherwise, and/or remain in their respective power managed states for longer periods than they would otherwise. 
     By way of illustration, the earlier triggering of I/O traffic  425  by Device  2  results in the ability of Memory to handle I/O traffic  425  before it has transitioned into a power managed state. This may mean that Memory can power down sooner and for a longer period of time, which eventually reduces the frequency with which Memory needs to transition between power states. The reduced power load allows improved system power management. For example, a system resource may power down upon completion of the initiated data traffic. Additionally or alternatively, an interface element such as a phase-locked loop (PLL) or a clock tree coordinating other interface elements may operate in a lower power or lower frequency state. 
       FIG. 5  includes an algorithm  500  implementing a method according to one embodiment of the invention. Algorithm  500  may be implemented, for example, by a data trafficking device including the features of data trafficking device  110 . In this exemplary algorithm  500 , the data trafficking device includes an input buffer to receive data provided by a target resource and an output buffer to receive data to be sent to a target resource. For the purpose of describing embodiments of the invention, the data trafficking device will only be considered as trafficking input buffer data and output buffer data with a single target resource. It is understood that this exemplary description of an embodiment of the invention may be expanded to include additional and/or alternate types of data traffic and/or additional and/or alternate target resources. 
     The algorithm begins at  510 , with the data trafficking device operable to initiate data traffic with the target resource. At  520 , the data trafficking device conducts its own internal buffering and debuffering operations, e.g. those buffer operations which do not require data traffic with the target resource. For example, the data trafficking device may be buffering data to the output buffer and/or debuffering data from the input buffer. At  530 , the data trafficking device may determine whether its own internal buffer operations have resulted in a need for data traffic with the target resource. If, at  540 , the data trafficking device has created its own need to traffic data with the target resource, the data trafficking device invokes the availability of the target resource for traffic. The invoking may cause the target resource and/or one or more other system resources to transition to an active power state, if some of those resources are not already in their respective power state. 
     If, at  550 , the data trafficking device has not created its own need to traffic data with the target resource, the data trafficking device determines whether there is an already existing power condition of a system resource to support data trafficking of the data trafficking device. In an embodiment of the invention, this determination may be based on an indication which is independent of any data traffic of the data trafficking device. If, at  580 , there exists no power condition to support data traffic with the target resource, the data trafficking device allows system resource to become unavailable. However, if, at  560 , there does exist some power condition to support data traffic with the target resource, the data trafficking device may receive any appropriate data traffic from the target resource to buffer in the input buffer. At  570 , the data trafficking device may send from the output buffer any appropriate data traffic to the target resource. As used herein, appropriate data traffic refers to an exchange of data which has been determined to justify the initiating of data traffic. In one embodiment, determining a data exchange which justifies initiating data traffic may be based on a relative benefit of initiating the data traffic in relation to a performance overhead associated with the initiated of data traffic. For example, an exchange of data to or from a particular buffer may not be appropriate, where the amount of data currently stored in the buffer fails to meet some threshold value. After any appropriate data traffic with the target resource has taken place, at  580 , the data trafficking device allows system resource to become unavailable. Then, at  520 , the data trafficking device may return to internal buffering operations and/or any other normal procedures, in anticipation of the next need and/or opportunity to initiate data traffic with the target resource. 
       FIG. 6  includes an algorithm  600  implementing a method according to one embodiment of the invention. In this exemplary case, the algorithm  600  may be more particularly implemented by a display device such as a monitor, graphics card, or similar video device. The data trafficking device may variously include the features previously discussed with reference to data trafficking device  110 , for example. In this exemplary algorithm  600 , the data trafficking device includes an input buffer to receive data provided by a target resource. At various times, the data trafficking device may debuffer an amount of data form the input buffer for use in providing display information. For the purpose of describing embodiments of the invention, the data trafficking device will only be considered as trafficking input buffer data with a single target resource. It is understood that this exemplary description of an embodiment of the invention may be expanded to include additional and/or alternate types of data traffic and/or additional and/or alternate target resources. 
     The algorithm begins at  610 , with the data trafficking device operable to initiate data traffic with the target resource. At  620 , the data trafficking device updates a display, wherein data has been debuffered from the input buffer for use in updating the system display. At  630 , the data trafficking device may determine whether its display update operations have resulted in a need for the target resource to provide more data for buffering in the input buffer. If, at  640 , the display update operations have created a need to traffic data with the target resource, the data trafficking device invokes the availability of the target resource for traffic. The invoking may cause the target resource and/or one or more other system resources to transition to an active power state, if some of those resources are not already in their respective power state. 
     If, at  650 , the display update operations have not created a need to traffic data with the target resource, the data trafficking device determines whether there is an already any other I/O traffic accessing the target resource. The existence of any other I/O traffic accessing the target resource serves as one type of indication that there is an already existing power condition (e.g. the power state of the target resource) of which the data trafficking device may avail in initiating data traffic. If, at  670 , there exists no other I/O traffic accessing the target resource, than the data trafficking device allows system resource to become unavailable. However, if, at  660 , there does exist some power condition to support data traffic with the target resource, the data trafficking device may receive any appropriate data traffic from the target resource to refill the input display buffer. After any appropriate data traffic with the target resource has taken place, at  670 , the data trafficking device allows system resources to become unavailable. Then, at  620 , the data trafficking device may return to performing regular system display updates and/or any other normal internal procedures, in anticipation of the next need and/or opportunity to initiate data traffic with the target resource. 
     Techniques and architectures for trafficking data are described herein. In the above description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form in order to avoid obscuring the description. Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
     An algorithm is here, and generally, conceived to be a self-consistent sequence of steps leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated (e.g. as bits, values, elements, symbols, characters, terms, numbers, or the like).