Matrix Algorithm for Processor Instruction Scheduling
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Solution Overview
Problem
Conventional processor-based systems face performance degradation due to inefficient instruction scheduling techniques, which can lead to timing issues and slow down logical elements like the floating-point unit.
Innovation Solution
A matrix algorithm is implemented for scheduling instructions, where a subset of instructions is selected based on their earliest program order within sub-matrices of a matrix, allowing for efficient selection of the next instruction to execute, potentially reducing the execution cycle from 2-cycles to 1-cycle for certain operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional instruction scheduling approaches are used, then the processor can execute instructions in program order with proper dependency handling, but the logical elements such as floating-point unit are slowed down leading to timing issues and performance degradation
Solution Approach 1:
The patent segments the instruction scheduling problem by dividing instructions into different categories (e.g., vector integer operations, floating-point operations) and applying different scheduling strategies to each segment. The matrix algorithm specifically segments the selection process by evaluating subsets of ready instructions rather than treating all instructions uniformly, allowing optimized scheduling paths for different operation types.
Solution Approach 2:
The patent performs preliminary actions by pre-calculating and maintaining a matrix of instruction dependencies and readiness states. The matrix algorithm pre-identifies which instructions are ready for execution and organizes them in a structured format before the actual selection occurs, eliminating the need for complex runtime dependency analysis and enabling faster instruction pick decisions.
2Measurement precision
If conventional scheduling methods are used to ensure proper instruction ordering and dependency resolution, then execution accuracy is maintained, but the scheduling process takes 2 cycles causing performance loss
Solution Approach 1:
The patent creates a simplified copy or representation of the instruction dependency structure in the form of a readiness matrix. Instead of analyzing the full complex dependency graph during instruction selection, the system uses this pre-computed matrix copy that directly indicates which instructions are ready, enabling O(1) or O(log n) selection time while maintaining complete dependency accuracy.
Solution Approach 2:
The patent changes the parameter representation from detailed dependency graphs to a simplified readiness matrix with binary indicators. This parameter transformation converts complex dependency relationships into simple ready/not-ready flags, allowing extremely fast selection based on matrix entries rather than complex graph traversal, thus reducing scheduling time from 2 cycles to 1 cycle.
Data Source
AI summary
The present invention provides a method and apparatus for implementing a matrix algorithm for scheduling instructions. One embodiment of the method includes selecting a first subset of instructions so that each instruction in the first subset is the earliest in program order of instructions associated with a corresponding one of a plurality of sub-matrices of a matrix that has a plurality of matrix entries. Each matrix entry indicates the program order of one pair of instructions that are eligible for execution. This embodiment also includes selecting, from the first subset of instructions, the instruction that is earliest in program order based on matrix entries associated with the first subset of instructions.