Scheduler Cancel Timer for Dependent Instruction Cancellation

Solution Overview

Problem

Existing microprocessor technologies consume significant time, power, and resources when canceling dependent instructions and resetting their source-ready state due to the need for extensive comparisons between destination and source tags.

Innovation Solution

Implementing a method that uses a single cancel indication and a cancel timer to simultaneously cancel direct and nested dependent instructions, resetting their source-ready bits when the timer expires, thereby reducing the need for extensive tag comparisons.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If destination tags of canceled producer instruction are compared with source tags of all instructions in the scheduler to reset source-ready state, then dependent instructions can be properly canceled, but the number of comparisons is enormous consuming time, power, and resources

Engineering Contradiction:

Improvecorrect cancellation of dependent instructionsVSAvoidtime for tag comparisons

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by setting a cancel timer when a producer instruction is speculatively executed. The timer is configured to expire after a predetermined time period, which is set in advance based on the expected execution time of the producer instruction. When the timer expires, the source-ready state of dependent instructions is automatically reset without requiring tag comparisons, thus preparing the system in advance for potential cancellation scenarios.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a cancel timer as an intermediary mechanism between the producer instruction cancellation and the dependent instruction state reset. Instead of directly comparing tags to determine cancellation, the timer serves as a mediator that triggers the reset operation after a predetermined time period, eliminating the need for extensive tag comparisons while ensuring proper cancellation timing.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If destination tags of canceled producer instruction are compared with source tags of all instructions in the scheduler to reset source-ready state, then dependent instructions can be properly canceled, but power consumption increases due to extensive comparisons

Engineering Contradiction:

Improvecorrect cancellation of dependent instructionsVSAvoidpower consumption for tag comparisons

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary action by setting a cancel timer when a producer instruction is speculatively executed. The timer is configured to expire after a predetermined time period, which is set in advance based on the expected execution time of the producer instruction. When the timer expires, the source-ready state of dependent instructions is automatically reset without requiring tag comparisons, thus preparing the system in advance for potential cancellation scenarios.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a cancel timer as an intermediary mechanism between the producer instruction cancellation and the dependent instruction state reset. Instead of directly comparing tags to determine cancellation, the timer serves as a mediator that triggers the reset operation after a predetermined time period, eliminating the need for extensive tag comparisons while ensuring proper cancellation timing.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If destination tags of canceled producer instruction are compared with source tags of all instructions in the scheduler to reset source-ready state, then dependent instructions can be properly canceled, but processing resources are consumed by extensive comparisons

Engineering Contradiction:

Improvecorrect cancellation of dependent instructionsVSAvoidprocessing resources for tag comparisons

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by setting a cancel timer when a producer instruction is speculatively executed. The timer is configured to expire after a predetermined time period, which is set in advance based on the expected execution time of the producer instruction. When the timer expires, the source-ready state of dependent instructions is automatically reset without requiring tag comparisons, thus preparing the system in advance for potential cancellation scenarios.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a cancel timer as an intermediary mechanism between the producer instruction cancellation and the dependent instruction state reset. Instead of directly comparing tags to determine cancellation, the timer serves as a mediator that triggers the reset operation after a predetermined time period, eliminating the need for extensive tag comparisons while ensuring proper cancellation timing.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9424041B2Efficient way to cancel speculative ‘source ready’ in scheduler for direct and nested dependent instructions

Publication Date: 2016.08.23 SAMSUNG ELECTRONICS CO LTD

AI summary

A method and apparatus for simultaneously canceling a dependent instruction and a nested dependent instruction when a cancel timer of a source of the dependent instruction and a cancel timer of a source of the nested dependent instruction expire and a producer instruction speculatively waking up the dependent instruction is canceled.