Split-Level History Buffer for CPU Register Management
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Solution Overview
Problem
Central processing units (CPUs) face performance issues due to limited memory capacity in history buffers, which can lead to reduced efficiency in managing architected register data and impacting CPU performance.
Innovation Solution
Implementing a split-level history buffer by partitioning it into two portions, where older data is evicted from the register file to the first-level history buffer and results are stored in the second-level history buffer, allowing for increased storage capacity and efficient management of tagged instructions and their results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single-level history buffer is used to manage architected register data, then the structure is simple, but the memory capacity is limited and CPU performance is impacted
Solution Approach 1:
The history buffer is divided into multiple levels (first-level and second-level history buffers) with different capacities and functions. The first-level buffer handles recent instructions while the second-level buffer stores older instructions, segmenting the single buffer into functional portions that collectively provide increased memory capacity without overwhelming complexity in a single structure.
Solution Approach 2:
The patent introduces a temporal dimension to the history buffer structure by organizing data across multiple levels representing different time periods. This dimensional expansion allows the system to store more historical data (increasing quantity) while maintaining manageable complexity through hierarchical organization rather than a single monolithic structure.
2Productivity
If the history buffer capacity is increased to manage more tagged instructions, then CPU performance improves, but the circuit area required increases
Solution Approach 1:
By segmenting the history buffer into multiple levels, the patent achieves increased storage capacity (improving CPU performance) while distributing the circuit area across hierarchical levels. This segmentation allows efficient use of storage resources and reduces the need for a single large buffer that would consume excessive circuit area.
Solution Approach 2:
The second-level history buffer is nested within or associated with the first-level buffer structure, allowing the system to expand capacity by adding nested levels rather than proportionally increasing the primary buffer. This nesting approach enables performance improvement while controlling overall circuit area consumption through efficient spatial utilization.
Data Source
AI summary
A split level history buffer in a central processing unit is provided. A history buffer is partitioned into a first portion and a second portion, wherein the first portion includes a first tagged instruction. A result is generated for the first tagged instruction. A determination whether a second tagged instruction is to be stored in the first portion of the history buffer is made. Responsive to the determination that the second tagged instruction is to be stored in the first portion of the history buffer, the first tagged instruction and the generated result for the first tagged instruction is written to the second portion of the history buffer.