Dynamic Cache Set Allocation for Speculative Execution
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Solution Overview
Problem
Current cache architectures face challenges in efficiently managing speculative and non-speculative execution threads, leading to inefficiencies in cache utilization and potential delays due to the lack of dynamic allocation and synchronization of cache resources.
Innovation Solution
The implementation of a cache system that dynamically allocates and interchanges cache sets between speculative and non-speculative executions using a spare cache set and background synchronization, allowing for efficient use of cache resources and reducing delays by utilizing a spare cache set for speculative executions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cache system uses static allocation of cache sets for speculative and non-speculative executions, then the cache structure is simple and easy to implement, but cache utilization efficiency deteriorates and delays occur due to inability to dynamically adapt to execution needs
Solution Approach 1:
The patent implements dynamic allocation of cache sets between speculative and non-speculative execution threads. The cache allocation is no longer static but changes based on the current execution state, allowing the system to adapt cache resources to the actual needs of different execution types, thereby improving cache utilization efficiency while managing complexity through structured dynamic control
Solution Approach 2:
The patent introduces a spare cache set that is pre-configured and reserved for speculative execution. This preliminary preparation allows speculative threads to immediately access dedicated cache resources when needed, avoiding delays associated with dynamic allocation during execution, thus improving productivity without requiring complex real-time allocation mechanisms
2Productivity
If cache sets are shared between speculative and non-speculative executions without reservation, then device complexity is reduced, but cache performance deteriorates due to resource contention and lack of dedicated resources
Solution Approach 1:
The patent segments the cache into multiple cache sets, with at least one cache set specifically designated as a spare cache set for speculative execution. This segmentation allows dedicated cache resources for different execution types, ensuring that speculative threads have immediate access to reserved cache space without competing with non-speculative threads, thereby improving cache access speed while maintaining manageable complexity through clear cache organization
Solution Approach 2:
The spare cache set is designed to be dynamically assignable - it can serve speculative execution when needed and be reallocated to non-speculative execution when the speculative thread is abandoned or completes. This multi-functionality allows the same cache infrastructure to support both execution types efficiently, improving productivity without requiring separate dedicated caches for each execution type
3Productivity
If the cache system transitions quickly between speculative and non-speculative executions without reservation, then productivity is improved, but reliability deteriorates due to potential data loss or corruption
Solution Approach 1:
The patent reserves a specific cache set for speculative execution before the speculative thread begins. This preliminary reservation ensures that when transitions between execution types occur, the speculative thread always has a pre-configured cache space to use, eliminating the need for complex data migration or validation during transitions, thus improving execution transition speed while maintaining data integrity through dedicated reserved space
Solution Approach 2:
The spare cache set can be quickly allocated and deallocated based on the lifecycle of speculative threads. When a speculative thread is abandoned, its associated cache set can be rapidly reallocated without complex cleanup or validation procedures, as the cache structure itself is designed to be easily reassignable. This approach improves transition speed while maintaining reliability through the inherent robustness of the cache allocation mechanism
Data Source
AI summary
A cache system, having cache sets, a connection to a line identifying an execution type, a connection to a line identifying a status of speculative execution, and a logic circuit that can: allocate a first subset of cache sets when the execution type is a first type indicating non-speculative execution, allocate a second subset when the execution type changes from the first type to a second type indicating speculative execution, and reserve a cache set when the execution type is the second type. When the execution type changes from the second to the first type and the status of speculative execution indicates that a result of speculative execution is to be accepted, the logic circuit can reconfigure the second subset when the execution type is the first type; and allocate the at least one cache set when the execution type changes from the first to the second type.