Selective Instruction Sequence Buffer for Processor Efficiency
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Solution Overview
Problem
Conventional micro-op caches consume high area and power to store micro-ops for complex instruction sequences, while micro-op buffers are limited to simple sequences, lacking an efficient solution for storing micro-ops of frequently-called complex sequences without excessive resource usage.
Innovation Solution
A selective instruction sequence buffer controller is introduced to store previously decoded micro-operations of frequently-called instruction sequences, determining their frequency of use and storing them in a buffer to reduce re-fetching and re-decoding, thereby disabling fetch and decode circuits and conserving power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a micro-op cache is used to store micro-ops for complex instruction sequences, then the processor can efficiently retrieve previously decoded micro-ops, but the area and power consumption increase significantly
Solution Approach 1:
The patent applies local quality by creating different types of storage structures with different characteristics: a fully associative micro-op cache for complex instruction sequences and a set-associative buffer for simpler sequences. This allows the system to optimize power consumption by using the lower-power buffer for common cases while maintaining the high-performance cache for when it's truly needed, rather than using the high-power cache for all micro-ops.
Solution Approach 2:
The patent segments the micro-op storage system into two distinct parts: a micro-op cache and a micro-op buffer. The buffer handles frequently accessed micro-ops from simple instruction sequences, while the cache handles more complex cases. This segmentation allows the system to reduce overall power consumption by avoiding full cache operations for routine micro-ops while maintaining high retrieval efficiency for frequently accessed sequences.
2Use of energy by stationary object
If a micro-op buffer is used instead of a micro-op cache, then area and power consumption are reduced, but the buffer can only store micro-ops for simple instruction sequences
Solution Approach 1:
The patent makes the system universal by designing it to handle multiple types of instruction sequences through different storage paths. The micro-op buffer is designed to handle simple sequences efficiently, while the micro-op cache provides backup capability for complex sequences that don't fit the buffer's constraints. This multi-functional approach allows the system to adapt to varying instruction sequence complexities without sacrificing power efficiency for the common case.
Solution Approach 2:
The patent introduces an intermediary classification mechanism that determines whether a micro-op sequence should be stored in the buffer or the cache. This intermediary layer analyzes the instruction sequence characteristics and routes them to the appropriate storage structure, enabling the system to maintain both power efficiency and versatility by matching the right storage type to the right instruction sequence.
3Loss of time
If frequently-called instruction sequences are stored in dedicated storage, then re-fetching and re-decoding are avoided, but the fetch and decode circuits must be temporarily disabled
Solution Approach 1:
The patent applies dynamics by making the storage system adaptive rather than static. The micro-op buffer dynamically learns which instruction sequences are frequently accessed and automatically stores them, while the system can dynamically switch between buffer and cache based on the current instruction sequence characteristics. This dynamic behavior allows the system to optimize for speed when patterns are recognized while maintaining circuit availability for handling new or varying instruction sequences.
Data Source
AI summary
Selective storing of previously decoded instructions of frequently-called instruction sequences in an instruction sequence buffer to be executed by a processor is disclosed. In one aspect, a selective instruction sequence buffer controller is configured to selectively store previously decoded instructions for an instruction sequence by determining if a received instruction address corresponds to an instruction sequence captured in an instruction sequence buffer. If the received instruction address corresponds to a captured instruction sequence, the selective instruction sequence buffer controller provides corresponding micro-operations stored in the instruction sequence buffer for execution. If the received instruction address does not correspond to the captured instruction sequence, the selective instruction sequence buffer controller reduces a frequency indicator of the instruction sequence. The selective instruction sequence buffer controller may also increase the frequency indicator of the instruction sequence when the instruction sequence is accessed, capturing the instruction sequence once the frequency indicator meets a threshold.