Dynamic Interrupt Reconfiguration for Power Management
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Solution Overview
Problem
Multi-core processors consume more power and generate more heat due to increased active processor circuitry under typical workloads, limiting power management efficiency and requiring operation at lower clock frequencies to reduce energy consumption and heat generation.
Innovation Solution
Dynamic interrupt reconfiguration through remapping interrupt vectors away from idle cores, allowing them to stay in deeper idle states without interruption, using an IRQ balancer and APIC to manage MSI/MSI-X interrupt requests and balance workload across processor cores.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple processor cores are kept active to service interrupt requests, then system responsiveness and interrupt handling capability are improved, but power consumption and heat generation increase
Solution Approach 1:
The system dynamically reconfigures interrupt vector mappings based on real-time workload conditions. When processor cores become idle, the IRQ balancer detects this state and remaps their interrupt vectors to active cores through the APIC, enabling idle cores to transition to deeper power-saving states while maintaining system interrupt handling capability
Solution Approach 2:
The IRQ balancer continuously monitors processor core states and automatically performs interrupt vector remapping when cores transition to idle states. This self-managed reconfiguration allows the system to optimize power consumption without external intervention, with the APIC and IRQ balancer working together to redistribute interrupt loads dynamically
2Use of energy by moving object
If processor cores are placed in deeper idle states to reduce power consumption, then energy efficiency is improved, but the ability to quickly respond to interrupt requests deteriorates
Solution Approach 1:
The system performs preliminary interrupt vector remapping before cores transition to deeper idle states. The IRQ balancer detects when a core is becoming idle and proactively remaps its interrupt vectors to active cores, ensuring that interrupt handling capability is maintained in advance, allowing the idle core to safely enter deeper power-saving states without compromising response speed
Solution Approach 2:
The APIC serves as an intermediary between interrupt sources and processor cores, managing the redirection of interrupt vectors. When cores transition to idle states, the APIC receives remapped interrupt vectors from the IRQ balancer and routes them to active cores, decoupling the idle state transition from interrupt handling and enabling both power savings and maintained responsiveness
3Use of energy by moving object
If interrupt vectors are remapped away from idle cores to enable deeper idle states, then power savings are achieved, but system complexity increases
Solution Approach 1:
The IRQ balancer performs multiple functions: it monitors processor core states, detects idle conditions, manages interrupt vector remapping through the APIC, and maintains system-wide interrupt handling coordination. This multi-functional component reduces the need for separate dedicated mechanisms for each task, managing complexity through consolidation while enabling dynamic interrupt reconfiguration for power savings
Data Source
AI summary
Methods, apparatus, and systems for facilitating effective power management through dynamic reconfiguration of interrupts. Interrupt vectors are mapped to various processor cores in a multi-core processor, and interrupt workloads on the processor cores are monitored. When an interrupt workload for a given processor core is detected to fall below a threshold, the interrupt vectors are dynamically reconfigured by remapping interrupt vectors that are currently mapped to the processor core to at least one other processor core, such that there are no interrupt vectors mapped to the processor core after reconfiguration. The core is then enabled to be put in a deeper idle state. Similar operations can be applied to additional processor cores, effecting a collapsing of interrupt vectors onto fewer processor cores. In response to detecting cores emerging from idle states, reconfiguration of interrupt vectors can be performed to rebalance the assignment of the vectors across active cores by remapping a portion of the vectors to those cores.