Abstract:
The present invention relates to a data processing system comprising both a high performance computing sub-system having typical high power consumption and a low performance subsystem requiring less power. The data processing system acts as a single computing device by moving the execution of software from the low performance subsystem to the high performance subsystem when high computing power is needed and vice versa when low computing performance is sufficient, allowing in the latter case to put the high performance subsystem into a power saving state. The invention relates also to related algorithms.

Description:
The present application is a U.S. National Stage Application of International Application No. PCT/NO2007/000010 filed on Jan. 10, 2007, which claims priority to U.S. Provisional Application No. 60/757,472 filed on Jan. 10, 2006. 
    
    
     TECHNICAL FIELD 
     The present invention relates to computer hardware and software. Specifically it relates to a computer system architecture to reduce electrical power consumption. 
     BACKGROUND AND PRIOR ART 
     With ever increasing computing power—increased clock frequency, more memory, wider data paths—also power consumption of computing equipment has increased. This in turn requires increased effort in removal of dissipated heat from the electronic components but also larger power supplies or—in case of mobile equipment—better energy storage (batteries). Many innovations have been implemented to reduce power consumption, but still the typical laptop drains its battery in less than a working day. 
     Besides reduction of power requirements in the field of the basic electronics (lower operational voltage for circuits f inst), some work has been done to also save power by simply powering down/switching off parts of a complex computing system when those parts are not needed for the current operation. The dichotomy is that computers often stand idle but consuming large amounts of power to maintain powerful processing capacitates, which is used only upon occasion. Many individuals computing needs could be met with little more than a smart-phones computing capacity. 
     Some attempts to address this issue have been made: 
     The international patent application WO2004064119 relates to a dual processor architecture—“Dualcor”—with two different processors and two operating systems (OS). These processors in this application are integrated on a single chip and share memory and graphics systems. 
     The Dualcor most resembles Intel patent number 20030088800 with the exception that it uses two OS to facilitate handheld use (read functionality) and reduced power consumption. Its claims are very similar to that of the Dualcor patent application. 
     An application presented by Marvell World, 20050182980 integrates a PDA (Personal digital Assistant) on to a Notebook computer, allowing the user to access the personal information management (PIM), email, and media (music) on a secondary screen with a several button input while allowing the x86 system to remain off, thus saving power. The computer includes a primary processor, a primary memory, and a primary input/output (I/O) interface that communicates with the primary processor and the primary memory. A primary display communicates with the primary I/O interface. The primary processor, the primary memory, and the primary display are operated in active and inactive modes and powered down when the computer is in the inactive mode. A secondary processor dissipates less power than the primary processor. A secondary display communicates with the secondary processor. The secondary processor and the secondary display are powered up when the computer is in the inactive mode. The secondary processor and display support PDA-like functionality when the computer is in the inactive mode. 
     The US patent application 20020129288 discloses a computing device having a low power secondary processor coupled to a keyboard controller for the primary applications: Media Notebooks—Instant on DVD/TV, which is designed to be installed over existing x86 systems. As such it does not have access to system components such as USB. In point 0017 of the patent it does provide for network connections, this seems to be directed toward connection to the Internet. The patent makes a full range of system peripheries available to the “secondary processor”. 
     Another US patent application 20030088800 presents a multi-processor mobile computer system having one low power processor integrated within a “highly integrated chipset” (Combined Northbridge and Southbridge) and a conventional main processor, thus creating a computer system having two processors of different clock frequencies and different levels of power consumption. An interface circuit can select one of the two processors to operate at a time to reduce power consumption without compromising the system performance. 
     Still there is a need for improving the prior art, which the present invention will do in several aspects. 
     SUMMARY 
     The present invention relates to a data processing system comprising a high-performance computing subsystems HP involving generally high power consumption and a low-performance computing subsystems LP having low power consumption. The invention is characterized in that the data processing system acts as a single computing device by moving the execution of a main operation alternatively to the high-performance subsystems HP when high computing performance is needed or the low-performance subsystems LP when low computing performance is sufficient. In the latter case the high-performance HP subsystems can be put into a power saving state. 
     The invention relates also to a method to coordinate a LP subsystem and a HP subsystem in a data processing system in order to transparently move a software between the subsystems making the subsystems to act as a single computing device. After an initial booting step (a) bringing the LP subsystem from off  200  to power-on  205  and keeping the HP subsystem powered-off  210  the method enters  215  a wait state (b),  220 . On need for high computing performance  225 , said HP subsystem is booted  230 ,  235  entering a booted state  240 . In the next step control of user interface means is transferred to the HP subsystem and the software to be executed is started  245 ,  250 ,  255 ,  260 . In a situation of annulment of the need  265  for high computing performance, control of the user interface means is transferred to the LP subsystem, the software is stopped and resources released  270 ,  275 . Then the HP subsystem is transferred into a power-saving mode and the method brings the system finally back to the wait state of step (b)  280 ,  285 ,  220 . 
     The invention relates further to a method to coordinate at least two sub-systems in a data processing system in order to transparently move an active main operation between those subsystems making those subsystems to act as a single computing device. This is done by two procedures, wherein the first procedure executes on the first subsystems and comprises the steps of (a) gathering information about the state of the main operation on the first subsystems, which comprises the state of allocated resources, (b) saving this state information to a storage means shared by both subsystems and (c) closing down the main operation on the first subsystems comprising releasing resources. The second procedure executing on a second subsystems comprises the steps of (i) fetching the saved information about the first state of the main operation from the shared storage means, (ii) starting up the main operation on the second subsystems comprising allocating resources according to the saved state information, and (iii) establishing a state on the second subsystems corresponding to the information about the first state. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Below the present invention will be described in greater detail with reference to the attached drawings, in which 
         FIG. 1  shows the block diagram of the complete data processing system structured in hardware, software, low-performance and high-performance sub-systems and shared equipment, 
         FIG. 2  shows a block diagram of the system more specifically aimed at the x86 architecture, presenting the low-performance processor connected to the I/O hub by PCI e and USB interface; 
         FIG. 3  gives a similar view as  FIG. 2 , but the LP-processor connects using USP and UART; 
         FIG. 4  shows the block diagram of a x86—“Southbridge” with the LP processor integrated; 
         FIG. 5  presents the state diagram for the process of moving the execution of application programs between the low- and high-performance sub-systems; 
         FIG. 6  illustrates an implementation as PCIe-card (=PCI express) for the x86 architecture; 
         FIG. 7  presents a block diagram for a detachable, stand-alone, low-performance module implementation; while 
         FIG. 8  corresponds to two procedures used in synchronizing both subsystems. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will now be described in detail with reference to the attached drawings. 
     The circumstance of unwanted high power consumption creates an opening for a computing system which is comprised of a high performance subsystem and a low performance subsystem. These two subsystems are then merged via hardware and software integration to create a single system. 
     In the industry standard situation, the invention can be implemented—but is not limited to it—in the x86 architecture best known as the PC architecture using the industry standard Intel x86 processor family or compatible processors which is used throughout this document as an example, but not limitation, for a high-performance, high-powered processor. The x86 architecture comprises the so-called Northbridge organizing the access of the central processor to internal volatile memory, the graphic processing and to the so-called Southbridge. The Southbridge handles all other IO and system management. The Northbridge and the above mentioned equipment attached to it, can be considered as the high-performance subsystem HP. Then, according to the present invention, a low-performance subsystem can be connected to or integrated into the Southbridge using a low-power, low-performance processor. This could for instance be an industry-standard ARM RISC-processor which will be used as an example, but not limitation in this document. 
       FIG. 1  shows a block diagram of a data processing system  100  comprising on the left side a high-performance computing subsystem HP with both a hardware part below and a software part above. Typical in computer electronics, high-performance equipment—everything else being equal—has high power consumption. The right side of the diagram shows a corresponding low-performance subsystem LP having lower power consumption compared with the high-performance subsystem HP. Both software and hardware are divided into layers with the common desktop  170 ,  175  at top, making the data processing system as a whole appear to the user substantially as a single computing device. Below the common desktop is the application layer  160 ,  165  followed by the operating-system. By moving the execution of software in the application layer to the low-performance, low-power subsystem as long as it still performs according to the user&#39;s expectation the high-performance subsystem HP can be set into a different state which conserves power or even be switched off completely when the low-performance subsystem executes the software. 
     In any case the low-performance subsystem LP is always active and runs the basic administration of the total system, and also ‘Always-On’ devices like any communication equipment (GPS, RF-modules, network interfacing components—NIC, WiFi, Bluetooth, GPRS, CDMA . . . ) may be connected to the LP sub-system. The operating systems (OS)  150 , 155  running on the subsystems are adapted to their respective computing performance and tasks. 
     To give the user the impression of working on a single computing device, it is important to retain a user interface and a use of peripheral devices independent, on which one of the subsystems the software is executed. To achieve this, the display means (typically a LCD-screen) is controlled by the low-performance subsystem LP while the high-performance subsystem HP is in a power saving/hibernating/off state, and by the high-performance subsystem HP while the HP subsystem is executing the software application or user programs—also called “main operation”—requiring high-performance computing resources. 
     As rather independent (sub-) systems of their own with largely different requirements for performance and power consumption, both systems comprise their own main processor, graphical processor and storage adapted to the specific requirements. 
     For further supporting the cooperation of the operating system of both sub-systems, at least one communication link  190  (IP link) interconnects the high-performance subsystem HP with the low-performance subsystem LP. This communication link  190  can provide a connection from the low-performance subsystem LP to the high-performance HP subsystem. This link uses IP/TCP or other protocols to link the two systems together. Although diagrammed in the software layer, the physical link is between I/O areas of respective systems. Peripheral devices can be shared using this link or by using a wider connection on the I/O Hub. This is dependent upon required system performance. 
     The subsystems typically share a common basic input/output system (BIOS) and an Advanced Configuration and Power Interface (ACPI). 
     The decision on which of the subsystems the-execution of the application program shall be moved to, is in one preferred embodiment indicated by a ‘switch’  180 , 185 , being a physical switch, a selector item as a part of the user interface on the computer display, or a result of software based evaluating a set of predetermined factors internal to the data processing system. 
     The switch changes typically the connection  125  of peripheral devices to that subsystem which is intended to execute the application program. This will allow the system to function in two distinct modes, each of which will be recognized by all peripheral devices as “Master” of the system depending on which CPU is active. 
       FIGS. 2 and 3  show a block diagram of the x86 architecture. Processor, volatile memory and graphics processing means are connected together and to the Southbridge by the Northbridge. The Southbridge acts as an I/O-hub for a number of protocols (SATA, PCIe, USB . . . ) and provides connectivity also for the low-performance subsystem LP. In  FIG. 2  this connectivity is as an example provided by a PCIe, forming the link to access the HP subsystem peripheral devices, and a USB channel used to transmit and receive data across the IP link  190 , while  FIG. 3  uses USB and UART for the same purposes. 
     The  FIGS. 2 and 3  indicate an implementation of the low-performance subsystem on the motherboard being a chip that sits next to the Southbridge and interfaces via any number of protocols while  FIG. 6  indicates the LP-subsystem being a detachable unit (PDA and the like), equipped with UI inputs (Keyboard, touchscreen, jog wheel, “five way directional pad” or similar inputs and display.), power source, antennas for embedded RF devices, ports, small screen UI suited to its form factor and use and other features characteristic of the product category. 
       FIG. 4  shows the block diagram of one possible embodiment of the present invention where the low-performance subsystem LP is implemented as a part of the x86 architecture Southbridge, this Southbridge also called the input/output hub  120 . An internal shared bus connects all internal I/O interface modules (PCIe, LAN, USB, AUDIO, SATA, IDE, DMA) and internal system administration modules (RESET, POWER, TEST, INTERRUPT, APIC) with the Northbridge, the BIOS and the integrated low-performance processor (ARM for instance), which in turn connects to external non-volatile memory, volatile memory, graphics, radio equipment and possibly more. 
       FIG. 6  shows an embodiment of the invention where the low-performance system is implemented as a PCIe card—both standard format and mini-PCIe for notebooks are possible. In addition to the components mentioned above in connection with the description of the other embodiments, here the card also comprises keyboard, mouse and display connectors and furthermore LAN, SATA, USB, AUDIO, network and other connectors enabling it to act as a low-performance, low-power subsystem LP according to the principles of the present invention. As being able already today, they could listen to network wake-up signals, but unlike today, they would in many cases not need to wake up the complete workstation, but rather do the requested job on their own. 
       FIG. 7  illustrates an embodiment of the invention, where the low-performance subsystem LP—together with an additional power supply and user interface means—forms a removable stand-alone data processing system like a PDA, Smartphone or the like, which together with a substantially larger unit provides a full-featured computing environment, but removed from this full-featured computing environment provides an ultra-portable minor-performance computing unit. 
     As a further embodiment of the invention, the presence of a second distinct CPU is used for multitasking and server client/protocols within the system where for example, tasks which are performed more power-efficiently on an ARM processor, can be handled by the secondary processor even when the x86 is active. In one case ARM functions as a slave processor for the x86, handling always on task such as GPRS, GPS and other radios, an Audio could also be handled by the ARM if so chosen. In another case the ARM would function as a server for the x86 system exposing services to the HP OS. 
     The possible state-switching logic according to the present invention is given in  FIG. 5 . Minor variants may occur dependent on implementations of the present invention. 
     It starts—state  200 —with the combined system being powered off: both subsystems, here being represented by the x86 known from the PC, and the ARM processor, typically applied in embedded applications such as mobile phones and PDA&#39;s. 
     Upon powering-on—transition  205 —from OFF-state  200  the LPBoot process begins. 
     State  210  is entered. Still the x86 remains off while the ARM is booting. After booting, the ARM enters state  220  (low power mode). After transition  215  ARM boot is finished. 
     The low-performance subsystem is now in state  220  “Low Power Mode”. In this state the ARM is in control of the device. This mode of operation allows users to perform various computing tasks with full access to peripheries on the device (such as hard drives and embedded radio frequency devices, cameras, other). With an ARM processor such tasks might include light office work, editing of documents, Use of calendar, email, music playback, video playback, personal entertainment programs and similar activities. 
     On a signal given the system enters  225  the state  230  and the high-performance x86 type processor starts its boot/resume routine. In state  230  the x86 is executing its boot sequence and gathers desktop and user environment information from database(s). The desktop, the user I/O and environment (that is pointing devices, character input and shared desktop, user settings for instance) remain in the control of the low-performance processor. The user may be notified of this process via UI cue otherwise it is undisturbed by said process. A signal transfers  235  the system over to state  240  indicating that the x86 has finished its boot sequence. At this point both processors and OS are running. Here error checking and data hand off for desktop and user environment may occur. The desktop and the user I/O and environment (that is pointing device, character input and shared desktop) still remain under the control of the low-performance processor. 
     The transition  245  shows that the processes of state  240  have been completed and state  250  is entered where switching user I/O between respective subsystems occurs. This may be characterized by a momentary flicker on the display means. An image from BIOS may be displayed, an on-screen timer, or other UI niceties may be used. 
     Transition  255  makes the system indicating that hand off of user I/O is complete and arriving in state  260 —“Full power mode”. In this mode the x86 controls both the UI and peripheries. 
     Transition  265  upon a signal transfers into state  270 . making the x86 to start to shutdown, ‘hibernate’ or ‘sleep’, switching user I/O between respective subsystems. This again may be characterized by a momentary flicker on the screen. User environment is described for ARM system. An image from BIOS may be displayed, an on-screen timer, or other UI niceties may be used. 
     After transition  275  hand off of user I/O is complete and the system arrives at state  280 —“Low Power Mode”. In this state the low-performance subsystem is in control of the device. This mode of operation allows users to perform various computing tasks with full access to peripheries on the device (such as hard drives and embedded radios). With an ARM processor such tasks might include light office work, editing of documents, use of calendar, email, music playback, video playback, personal entertainment programs and similar activities. 
     The transition  285  indicates the x86 shutdown/sleep/hibernation process continues until completed. The system arrives at state  220  again. 
     A timeout function during this state can transfer  289  the system into state  290 , a standby state where even the ARM is in a sleep-mode, some user I/O is off, the whole system consuming even less power. Any wake-up event (PoC—Point of Contact, ex. keyboard input, incoming call on GPRS, calendar event) will initiate the opposite transition  291  and put the system in state  220 . 
     The invention concerns also a method according to the flow chart in  FIG. 8  to coordinate the two subsystems in order to transparently move the software to be executed between the subsystems making these subsystems to act as a single computing device. 
     The method comprises two procedures, the first procedure executed on the first subsystem comprising the steps: (a) gathering information about the state of the software on the first subsystem including information about allocated resources ( 300 ); then (b) storing the this state information to a storage means shared by both subsystems ( 310 ), and (c) closing down the software on the first subsystem including releasing/unmounting the resources ( 320 ). The second procedure executes on the second subsystem and includes the steps (i) fetching the stored information about the first state of the software from the shared storage means ( 330 ), (ii) starting up the software on the second subsystem comprising also allocating/mounting the resources according to the above mentioned saved state information ( 340 ), (iii) establishing a second state on the second subsystem corresponding to information about the first state ( 350 ), and (iv) saving the second state information to a storage means shared by both subsystems ( 360 ). 
     In a typical embodiment a final step (d) in the first procedure comprises putting the first subsystem into a passive, power saving state. 
     According to one embodiment of the invention parts of the state information on the storage means are updated dynamically, when these part are observed to change on the subsystem, are updated sequentially as the operating system is in process, or are updated as system resources become available to execute background tasks. 
     Generally speaking the present invention can be embodied as combinations of software and hardware modules, but will typically be implemented as a set of hardware gate logic optimized for use in a given chipset and integral with the mentioned input/output hub (“Southbridge”).