Code Prefetch Instruction for Multi-Cache Bandwidth Control
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Solution Overview
Problem
Existing processors face inefficiencies due to cache capacity and memory bandwidth pressure from unnecessary code prefetching, leading to wasted resources and reduced performance.
Innovation Solution
Implementing a single code prefetch instruction to prefetch multiple code blocks into multiple caches at different levels, combined with a performance monitoring unit to adjust prefetching based on collected execution data, optimizing the balance between performance benefits and negative effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If code prefetching is implemented to improve program execution efficiency, then idle time is reduced and performance is improved, but cache capacity and memory bandwidth are wasted due to unnecessary prefetching
Solution Approach 1:
The patent implements a feedback mechanism where the performance monitoring unit collects execution data and feeds it back to adjust prefetching operations. The system monitors whether prefetched code blocks are actually executed and uses this information to dynamically adjust future prefetching behavior, preventing waste of cache capacity and memory bandwidth on unnecessary prefetching while maintaining improved program execution efficiency.
Solution Approach 2:
The patent makes the prefetching system dynamic by allowing it to adjust its behavior based on runtime conditions. The performance monitoring unit tracks execution patterns and modifies prefetching parameters dynamically, transforming the static prefetching approach into an adaptive system that optimizes the balance between reducing idle time and minimizing resource waste.
2Loss of time
If multiple code blocks are prefetched into multiple caches simultaneously, then idle time is reduced and execution efficiency is improved, but device complexity increases due to coordination requirements
Solution Approach 1:
The patent combines multiple prefetching operations into a unified instruction (PCODE prefetch instruction) that can prefetch multiple code blocks into multiple caches simultaneously. This merging approach reduces the number of separate instructions needed and simplifies the control logic while maintaining the ability to reduce idle time through parallel prefetching operations.
Solution Approach 2:
The patent creates a universal prefetching mechanism that can operate across multiple cache levels and prefetch multiple code blocks through a single instruction. This multi-functional approach reduces the complexity that would otherwise arise from having separate prefetching mechanisms for each cache level, while still achieving reduced idle time through simultaneous prefetching.
Data Source
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AI summary
In an embodiment, a processor includes a fetch circuit to fetch instructions, the instructions including a code prefetch instruction; a decode circuit to decode the code prefetch instruction and provide the decoded code prefetch instruction to a memory circuit, the memory circuit to execute the decoded code prefetch instruction to prefetch a first set of code blocks into a first cache and to prefetch a second set of code blocks into a second cache. Other embodiments are described and claimed.