1. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 1 Dynamic power management for embedded system “ Dynamic power management for embedded system” Under the guidance of Mr. Shyamalendu Mohanty

2. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 2 Dynamic power management for embedded system Introduction  This dynamic power management refers to power management schemes implemented while programs are running.  This architecture is based on the capabilities of current and next-generation processors and their application requirements.

3. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 3 Dynamic power management for embedded system REQUIREMENTS  The overriding power management goal in portable system is to reduce system-wide energy consumption.  Dynamic power management is only concerned with voltage and frequency.  Dynamic power management architecture supports the ability of processors and external bus frequencies, in concerned with or even independent of the CPU frequency.

4. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 4 Dynamic power management for embedded system ARCHITECTURAL OVER VIEW A high-level view of dynamic power management

5. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 5 Dynamic power management for embedded system  The low-level implementation of the dynamic power management architecture (DPM) is resident in the kernel of the operating system.  DPM is not a self-contained device driver.  Complete power management strategy is communicated to DPM in to ways: as an predefined set of policies and as an application/policy-set specific manager that manages them.

6. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 6 Dynamic power management for embedded system  Policies specify the component and device-state transitions that ensure reliable operation in line with the power management strategy.  DPM policy managers are executable programs that activate policies by name.  Policy managers implement user defined and/or application-specific power management strategies. They can execute either as part of the kernel or in user space (or both) as required by the strategy.

7. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 7 Dynamic power management for embedded system POLICY ARCHITECTURE  OPERATING POINTS Operating point may be described different parameters such as core voltage, CPU bus frequencies and states of peripheral devices. Operating points for the IBM PowerPC 405LP specify a core voltage level, CPU and bus frequencies, memory timing parameters and other clocking related data.

8. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 8 Dynamic power management for embedded system  OPERATING STATES In dynamic power management policy, operating state associated with an operating point specific to the requirements of that state. Operating state was the observation that includes the system-wide energy savings, it can be done by reducing CPU and bus frequency and core voltage while the system is in ideal state.

9. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 9 Dynamic power management for embedded system  POLICIES AND POLICY MANAGER Policy maps each operating state to a congruence class of operating point. Policy manager collect information from the operating system, user performances, running programs, configuration files and/or physical devices to make it policy decisions.

10. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 10 Dynamic power management for embedded system  Automatic selection of operating points as devices change states is a central feature of DPM.  Embedded systems may not have a BIOS or machine abstraction layer to insulate the operating system from low-level device and power management.  The most aggressive power management strategies will also require the system designer to carefully consider the influence of attached devices on the strategy. DEVICE CONSTRAINT MANAGER

11. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 11 Dynamic power management for embedded system ABSTRACT IMPLIMENTATION  This Section gives our preferred implementation and the rationale behind the choices made in the implementation.  Two of the challenges with respect to implementing this system include: Changes in device constraints may invalidate operating points. Automating these transitions is the primary mechanism by which the architecture

12. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 12 Dynamic power management for embedded system relieves the high-level power management task from having to deal with device states. This leads to several conflicts. Operations on the DPM implementation may block. Blocking could arise at the very lowest level of the implementation, where power management device drivers use system I/O ports to control voltages and frequencies.

13. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 13 Dynamic power management for embedded system  task-specific operating points,implemented by assigning different task operating states to different tasks.  The task state of a task is changed by the set_task_state () entry point, which may be exported to the user level as a system call.  Thus a system can be constructed where a single intelligent policy manager controlled the task states of critical programs for improved power/performance efficiency. Implementation and Effects Of task_specific Operating States

14. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 14 Dynamic power management for embedded system CONCLUSION This paper has proposed an architecture supporting aggressive dynamic power management for embedded systems. The power management schemes implemented while programs are running. Dynamic power management strategies based on dynamic voltage and frequency scaling.

15. Technical Seminar Presentation 2004 Presented by- Geetanjali Konhar EE 200167O81 15 Dynamic power management for embedded system THANK YOU