Credit-Based Instruction Issue Control for Deadlock-Safe Processors
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Solution Overview
Problem
Conventional power management techniques for processor devices, such as throttling instruction issuance rates, risk introducing deadlock situations and excessive delays, negatively impacting performance.
Innovation Solution
Implementing a credit-based mechanism using a credit logic circuit to control instruction issue rate, where a credit counter determines the number of instructions that can be issued within a time window, blocking further issuance if the counter falls below a threshold, and replenishing credits at the start of each interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If conventional throttling techniques using randomly generated blocking vectors are used to limit instruction issue rate, then power consumption is reduced, but deadlock situations and excessive delays occur
Solution Approach 1:
The patent implements a feedback mechanism where the credit logic circuit continuously monitors the credit counter value and dynamically adjusts instruction issuance based on current power management policies. The block signal is asserted or deasserted based on real-time comparison of the credit counter against the blocking threshold, creating a closed-loop control system that prevents deadlock while managing power consumption effectively.
Solution Approach 2:
The credit logic circuit acts as an intermediary between the reservation station circuit and the power management requirements. It translates power management policies into concrete instruction issuance decisions by using the credit counter and block signal mechanism, thereby mediating between performance and power consumption without causing deadlock.
2Use of energy by stationary object
If conventional throttling techniques using randomly generated blocking vectors are used to limit instruction issue rate, then power consumption is reduced, but excessive delays occur
Solution Approach 1:
The feedback mechanism ensures that instruction issuance is adjusted dynamically based on the credit counter state. When credits are available, instructions are issued without delay; when the threshold is approached, the block signal is asserted to prevent power violations. This real-time feedback eliminates excessive delays while maintaining power constraints.
Solution Approach 2:
The system transitions from static random blocking vectors to a dynamic credit-based mechanism that adapts to current processor state and power management requirements. The credit counter and block signal provide dynamic control over instruction issuance timing, optimizing both performance and power consumption.
3Use of energy by stationary object
If a credit-based mechanism with block signal is used to control instruction issue rate, then power consumption is managed effectively and deadlock is prevented, but device complexity increases
Solution Approach 1:
The control mechanism is segmented into distinct functional components: the credit counter for tracking available instruction issuances, the comparison logic for threshold evaluation, and the block signal generation for enforcement. This segmentation makes the complex control mechanism more manageable and implementable while achieving effective power management.
Data Source
AI summary
Controlling instruction issue rate using credit-based mechanisms in processor devices is disclosed herein. In some aspects, a processor device comprises a credit logic circuit that is communicatively coupled to a reservation station (RS) circuit, and that comprises a credit counter. The credit logic circuit receives an instruction issue indication for an instruction from the RS circuit during a time interval. The credit logic circuit decrements a value of a credit counter. The credit logic circuit also determines whether the value of the credit counter equals or is less than a blocking threshold, and, if so, asserts a block signal to the RS circuit. The RS circuit is configured to receive the block signal, and, responsive to receiving the block signal, block further instruction issuance during the time interval.