Abstract:
As disclosed herein, a method, executed by a computer, includes comparing a current power consumption profile for a computing task with an historical power consumption profile, receiving a request for a computing resource, granting the request if the historical power consumption profile does not suggest a pending peak in the current power consumption profile or the historical power consumption profile indicates persistent consumption at a higher power level, and denying the request for the computing resource if the historical power consumption profile suggests a pending peak in the current power consumption profile and the historical power consumption profile indicates temporary consumption at the higher power level. Denying the request may include initiating an allocation timeout and subsequently ending the allocation timeout in response to a drop in a power consumption below a selected level. A computer system and computer program product corresponding to the method are also disclosed herein.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to the field of resource allocation in computing systems, and more particularly to managing power in such systems. 
         [0002]    In system virtualization, multiple virtual computing systems are created within a single physical computing system. The physical system can be a stand-alone computer, or alternatively, a computing system utilizing clustered computers and components. Virtual systems are independent operating environments that use virtual resources made up of logical divisions of physical resources such as processors, memory, and input/output (I/O) adapters. System virtualization is implemented through some managing functionality, typically hypervisor technology. Hypervisors, also called virtual machine managers (VMMs), use software or firmware to achieve fine-grained, dynamic resource sharing. Hypervisors are the primary technology for system virtualization because they provide the greatest level of flexibility in how virtual resources are defined and managed. 
         [0003]    Hypervisors provide the ability to divide physical computing system resources into isolated logical partitions. Each logical partition operates like an independent computing system running its own operating system (e.g., a virtual system). Operating systems running in a virtualized environment are often referred to as “guest machines.” Exemplary operating systems include AIX®, IBM® i, Linux®, and the virtual I/O server (VIOS). Hypervisors can allocate dedicated processors, I/O adapters, and memory to each logical partition and can also allocate shared processors to each logical partition. Unbeknownst to the logical partitions, the hypervisor creates a shared processor pool from which the hypervisor allocates virtual processors to the logical partitions as needed. In other words, the hypervisor creates virtual processors from physical processors so that logical partitions can share the physical processors while running independent operating environments. 
         [0004]    The hypervisor can also dynamically allocate and de-allocate dedicated or shared resources (such as processors, I/O, and memory) across logical partitions while the partitions are actively in use. This is known as dynamic logical partitioning (dynamic LPAR) and enables the hypervisor to dynamically redefine all available system resources to reach optimum capacity for each partition. 
         [0005]    One aspect of dynamic resource allocation that is often ignored is power consumption. Although power consumption tends to correlate with the amount and type of allocated resources spikes in power consumption may come at unexpected times. Such spikes require computing systems to have larger power supplies and may increase utility bills which are often based on peak usage. The ability to better control power consumption spikes would be an advancement in the art. 
       SUMMARY 
       [0006]    As disclosed herein, a method, executed by a computer, includes comparing a current power consumption profile for a computing task with an historical power consumption profile for the computing task, receiving a request for a computing resource, granting the request for the computing resource if the historical power consumption profile does not suggest a pending peak in the current power consumption profile or the historical power consumption profile indicates persistent consumption at a higher power level, and denying the request for the computing resource if the historical power consumption profile suggests a pending peak in the current power consumption profile and the historical power consumption profile indicates temporary consumption at the higher power level. Denying the request for the computing resource may include initiating an allocation timeout and subsequently ending the allocation timeout in response to a drop in a power consumption below a selected level. The method provides improved power management. A computer system and computer program product corresponding to the method are also disclosed herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a functional block diagram of one embodiment of a virtualized computer environment in which at least some of the embodiments disclosed herein may be deployed; 
           [0008]      FIG. 2  is a flowchart depicting one embodiment of a resource management method; 
           [0009]      FIG. 3 a    is a flowchart depicting one embodiment of a resource throttling method; 
           [0010]      FIG. 3 b    is a flowchart depicting one embodiment of a resource allocation method; 
           [0011]      FIGS. 4 a  and 4 b    are graphs depicting the effect of the present invention on power consumption profiles; and 
           [0012]      FIG. 5  is a block diagram depicting one example of a computing apparatus (i.e., computer) suitable for executing the methods disclosed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The embodiments disclosed herein provide improved power management in a computing system by dynamically controlling the allocation of resources. 
         [0014]      FIG. 1  is a functional block diagram of one embodiment of a virtualized computer environment  100  in which at least some of the embodiments disclosed herein may be deployed. Virtualized computer environment  100  includes computer  102 . Computer  102  has been divided into multiple logical partitions  104 ,  106 , and  108 . In the illustrated example, each of the respective logical partitions  104 ,  106 , and  108  runs an independent operating environment, such as an OS. Logical partition  104  runs an OS  132 , which can be AIX®, logical partition  106  (hereafter VIOS partition  106 ) runs a VIOS  134 , and logical partition  108  runs an OS  136 , which can be Linux®. Other operating environments and combinations of operating environments may be used. In another embodiment, any number of partitions may be created and may exist on separate physical computers of a clustered computer system. 
         [0015]    Communications from external network  110  may be routed through Shared Ethernet adapter (SEA)  112  on VIOS partition  106  to virtual adapters  114  and  116  on respective logical partitions  104  and  108 . Communications from virtual adapters  114  and  116  on respective logical partitions  104  and  108  may be routed through Shared Ethernet adapter (SEA)  112  on VIOS partition  106  to external network  110 . In an alternative embodiment, physical network adapters may be allocated to logical partitions  104 ,  106 , and  108 . 
         [0016]    Hypervisor  118  forms logical partitions  104 ,  106  and  108  from the physical computing resources of computer  102  through logical sharing of designated physical computing resources (or portions thereof) such as processors  120 , storage disks  122 , I/O adapters  124  (e.g., network interface cards), and/or memory  126 . Hypervisor  118  performs standard operating system functions and manages communications between logical partitions  104 ,  106 , and  108  via virtual switch  128 . 
         [0017]    Logical partitions  104 ,  106 , and  108  each include various programs or tasks  130  and various physical resources such as processors  120 , disks  122 , I/O adapters  124 , and memory  126 . The hypervisor  118  allocates all or a portion of the physical resources (e.g., a portion of the available bandwidth) to one or more programs  130  which may be executing in different logical partitions. The present invention may be leveraged by the hypervisor  118  in order to control power consumption within the virtualized computer environment  100 . 
         [0018]      FIG. 2  is a flowchart depicting one embodiment of a resource management method  200 . As depicted, the resource management method  200  includes allocating ( 210 ) a base set of resources, determining ( 220 ) whether a process should be terminated, de-allocating ( 230 ) one or more resources, determining ( 240 ) whether a resource has been requested, determining ( 250 ) whether a power transition is expected, determining ( 260 ) whether a power consumption peak is expected, granting ( 270 ) a resource request, and denying ( 280 ) the resource request. The resource management method  200  provides power consumption management by controlling resource allocation in a computing system or environment such as the virtualized computer environment  100 . One skilled in the art will appreciate that, for the purpose of simplicity, the method  200  is presented as a single polling process with a number of conditional tests. However, the method  200  may be implemented (perhaps preferably) as an event driven process or set of processes. 
         [0019]    Allocating ( 210 ) a base set of resources may include reserving a predetermined set of resources. In some embodiments, the predetermined set of resources is a minimal set of resources required to enable execution of a process or task (which could involve multiple processes). For example, a processor  120  or a portion of the CPU time of the processor  120  along with some memory  126  may be required to begin execution. Additional resources may be allocated on demand. 
         [0020]    Determining ( 220 ) whether a process should be terminated may include determining whether the process has completed execution of the program associated with the process or determining if a kill signal or some other termination mechanism has been activated that references the process. If the process should not be terminated, the method proceeds to de-allocating ( 230 ) one or more resources. If the process should be terminated, the method proceeds to determining ( 240 ) whether a resource has been requested. De-allocating ( 230 ) one or more resources may include de-allocating all of the resources assigned to a process that is to be terminated. Subsequent to de-allocating, the method terminates. 
         [0021]    Determining ( 240 ) whether a resource has been requested may include checking an event flag or accessing some other signaling mechanism. Alternately, a resource request may be an event driven occurrence. If a resource has not been requested, the depicted method loops to the determining step  220 . If a resource has been requested, the depicted method proceeds to the determining operation  250 . 
         [0022]    Determining ( 250 ) whether a power transition is expected may include checking a historical power consumption profile to ascertain whether an increase in power consumption is expected. The historical power consumption profile (as well as a current power consumption profile) may be estimated from resource utilization information or collected from repeated direct measurements of power consumption. In some embodiments, power consumption is divided into discreet levels that have an upper and lower threshold. The discreet levels may correspond to resource granularity. In other embodiments, relative changes in power consumption are quantized rather than absolute levels. Consequently, determining ( 250 ) whether a power transition is expected may include ascertaining if an expected transition to a higher power consumption level (absolute or relative) is imminent. If a transition is expected, the method advances to the granting operation  270 . If a transition is not expected, the method continues by determining ( 260 ) whether a power consumption peak is expected. 
         [0023]    Determining ( 260 ) whether a power consumption peak is expected may include checking the historical power consumption profile or markers associated therewith to ascertain whether a peak in power consumption is expected. If a peak is expected, the method advances by denying ( 280 ) the resource request. If a peak is not expected, the method continues by granting ( 270 ) the resource request. 
         [0024]    Granting ( 270 ) a resource request may include conducting the method of  FIG. 3 b   . Denying ( 280 ) the resource request may include conducting the method of  FIG. 3 a   . In some embodiments, denial of the resource request is temporary. 
         [0025]      FIG. 3 a    is a flowchart depicting one embodiment of a resource throttling method  300 . As depicted, the resource throttling method  300  includes initiating ( 310 ) an allocation timeout, determining ( 320 ) whether power consumption has been reduced, allocating ( 330 ) a requested resource, and updating ( 340 ) a power consumption profile. The resource throttling method  300  may be used to implement the deny resource operation  280  within the resource management method  200 . 
         [0026]    Initiating ( 310 ) an allocation timeout may include setting a status flag or the like for the process or the requested resource indicating that allocation of the requested resource or all resources are to be delayed. In some embodiments, a timer is set that determines the duration of the allocation timeout. 
         [0027]    Subsequent to initiating ( 310 ) an allocation timeout (either immediately or after a selected wait time) the method continues by determining ( 320 ) whether power consumption has been reduced (e.g. as a consequence of initiating the allocation timeout). In some embodiments, power consumption (or the change in power consumption) is compared to a specific threshold. If power consumption has been reduced the method terminates. If power consumption has not been reduced, the method  300  advances to allocating ( 330 ) the requested resource. 
         [0028]    Allocating ( 330 ) a requested resource may include a standard resource allocation process that is well known to those skilled in the art. One skilled in the art may appreciate that the allocating operation ( 330 ) may be conducted when it becomes apparent that initiating ( 310 ) an allocation timeout is not effective in reducing power consumption below the selected threshold level (e.g., the minimum value for a particular power consumption level) and the increase in power consumption is likely to be sustained. Consequently, a particular historical power consumption profile that indicated a peak in power consumption may no longer be accurate for the computing task. In recognition of this situation, the method continues by updating ( 340 ) the power consumption profile. 
         [0029]    Updating ( 340 ) the power consumption profile may include copying a current power consumption profile to the historical power consumption profile. Subsequent to updating ( 340 ) the power consumption profile, the method  300  ends. 
         [0030]      FIG. 3 b    is a flowchart depicting one embodiment of a resource allocation method  350 . As depicted, the resource allocation method  350  includes allocating ( 360 ) a requested resource, initiating and waiting ( 370 ) for a timeout, determining ( 380 ) whether power consumption has been reduced, and marking ( 390 ) a peak in the power consumption. The resource allocation method  300  may be used to implement the grant resource operation  270  within the resource management method  200 . 
         [0031]    Allocating ( 360 ) a requested resource may include conducting a standard resource allocation process that is well known to those skilled in the art. Initiating and waiting ( 370 ) for a timeout may include setting a timer to elapse, or timing event to trigger, at a selected time. Determining ( 380 ) whether power consumption has been reduced may include comparing a current power consumption level with a previous power consumption level. One skilled in the art will recognize that the determining operation  380  may be essentially identical to the determining operation  320 . Marking ( 390 ) a peak in power consumption may include annotating a data structure or table to indicate that a specific point in a power consumption profile is a peak. 
         [0032]      FIGS. 4 a  and 4 b    are graphs depicting the effect of some embodiments of the present invention on power consumption profiles. As shown in  FIG. 4 a   , one or more historical power consumption profiles  410   a , indicate that the consumed power for a computing task temporarily exceeds a threshold  420 , resulting in one or more peaks  430 . Each power consumption profile  410   a  may correspond to an occurrence or instance of executing the computing task. In the depicted embodiment, the power consumption profiles  410   a  represent the consumed power (vertical axis) tracked over the execution time (horizontal axis) of the task. 
         [0033]    In some embodiments, tracking the consumed power includes determining a minimum, maximum, and average value for the consumed power within quantized time intervals  450 . Power consumption peaks  430  may be detected and marked resulting in a marked interval  440  for a computing task. Subsequent to detecting and marking peaks  430 , resource allocation for a new instance of the computing task may deny or defer allocation of computing resources near the marked interval  440  resulting in a current power consumption profile  410   b  (see  FIG. 4 b   ) that does not exceed the threshold  420 . 
         [0034]      FIG. 5  is a block diagram depicting components of a computer  500  suitable for executing the methods disclosed herein. The computer  500  may be one embodiment of the data processor  102  depicted in  FIG. 1 . It should be appreciated that  FIG. 5  provides only an illustration of one embodiment and does not imply any limitations with regard to the environments in which different embodiments may be implemented. Many modifications to the depicted environment may be made. 
         [0035]    As depicted, the computer  500  includes communications fabric  502 , which provides communications between computer processor(s)  505 , memory  506 , persistent storage  508 , communications unit  512 , and input/output (I/O) interface(s)  515 . Communications fabric  502  can be implemented with any architecture designed for passing data and/or control information between processors (such as microprocessors, communications and network processors, etc.), system memory, peripheral devices, and any other hardware components within a system. For example, communications fabric  502  can be implemented with one or more buses. 
         [0036]    Memory  506  and persistent storage  508  are computer readable storage media. In the depicted embodiment, memory  506  includes random access memory (RAM)  516  and cache memory  518 . In general, memory  506  can include any suitable volatile or non-volatile computer readable storage media. 
         [0037]    One or more programs may be stored in persistent storage  508  for execution by one or more of the respective computer processors  505  via one or more memories of memory  506 . The persistent storage  508  may be a magnetic hard disk drive, a solid state hard drive, a semiconductor storage device, read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, or any other computer readable storage media that is capable of storing program instructions or digital information. 
         [0038]    The media used by persistent storage  508  may also be removable. For example, a removable hard drive may be used for persistent storage  508 . Other examples include optical and magnetic disks, thumb drives, and smart cards that are inserted into a drive for transfer onto another computer readable storage medium that is also part of persistent storage  508 . 
         [0039]    Communications unit  512 , in these examples, provides for communications with other data processing systems or devices. In these examples, communications unit  512  includes one or more network interface cards. Communications unit  512  may provide communications through the use of either or both physical and wireless communications links. 
         [0040]    I/O interface(s)  515  allows for input and output of data with other devices that may be connected to computer  500 . For example, I/O interface  515  may provide a connection to external devices  520  such as a keyboard, keypad, a touch screen, and/or some other suitable input device. External devices  520  can also include portable computer readable storage media such as, for example, thumb drives, portable optical or magnetic disks, and memory cards. 
         [0041]    Software and data used to practice embodiments of the present invention can be stored on such portable computer readable storage media and can be loaded onto persistent storage  508  via I/O interface(s)  515 . I/O interface(s)  515  may also connect to a display  522 . Display  522  provides a mechanism to display data to a user and may be, for example, a computer monitor. 
         [0042]    The programs described herein are identified based upon the application for which they are implemented in a specific embodiment of the invention. However, it should be appreciated that any particular program nomenclature herein is used merely for convenience, and thus the invention should not be limited to use solely in any specific application identified and/or implied by such nomenclature. 
         [0043]    The embodiments disclosed herein include a system, a method, and/or a computer program product. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out the methods disclosed herein. 
         [0044]    The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire. 
         [0045]    Computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device. 
         [0046]    Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like, and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user&#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). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention. 
         [0047]    Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions. 
         [0048]    These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks. 
         [0049]    The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks. 
         [0050]    The flowcharts and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions.