Control Circuitry for Dynamic Data Allocation in Memory Hierarchies
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Solution Overview
Problem
In memory hierarchies, data that is not expected to be reused soon can lead to inefficiencies due to incorrect eviction policies, causing increased bandwidth and power consumption as less useful data is evicted, potentially leading to cascades of evictions and performance delays when needed again.
Innovation Solution
Implementing an operating mode control system that allows data to be stored in an intermediate buffer instead of higher-level storage circuitry, suppressing allocation to storage circuitry when data is unlikely to be reused, thereby reducing unnecessary evictions and preserving more useful data in the storage circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data is allocated to higher-level storage circuitry in a memory hierarchy, then data access speed is improved, but bandwidth and power consumption increase due to unnecessary allocations and evictions
Solution Approach 1:
The system dynamically switches between allocation mode and non-allocation mode based on data reuse probability. When data is determined to be unlikely to be reused soon, the system transitions to non-allocation mode, suppressing allocations to higher-level storage circuitry. This dynamic adaptation allows the system to optimize between fast access (when data is reused) and energy efficiency (when data is not reused), resolving the contradiction between speed and power consumption.
Solution Approach 2:
The system changes the allocation parameter (whether to allocate data to higher-level storage) based on the reuse probability of the data. By monitoring and evaluating data access patterns, the system adjusts the allocation behavior - allocating when reuse is likely and suppressing allocation when reuse is unlikely. This parameter change enables the system to reduce unnecessary bandwidth usage and power consumption while maintaining fast access performance when needed.
2Loss of time
If data is allocated to higher-level storage circuitry, then data access latency is reduced, but system efficiency deteriorates due to incorrect eviction policies causing cascades of evictions
Solution Approach 1:
The system dynamically adjusts allocation behavior based on data reuse probability. When data is identified as unlikely to be reused soon, the system suppresses allocation to higher-level storage circuitry, preventing incorrect evictions and cascading effects. This dynamic control maintains system efficiency by ensuring that only data with high reuse probability occupies higher-level storage, thereby avoiding the productivity deterioration caused by unnecessary evictions while still reducing latency for frequently accessed data.
Solution Approach 2:
The system implements feedback mechanisms to monitor data access patterns and reuse probability. By continuously evaluating whether data is likely to be reused, the system provides feedback to the allocation decision-making process. This feedback loop prevents incorrect allocations that would lead to cascades of evictions, thereby maintaining system efficiency while still achieving low latency for data that deserves to be in higher-level storage.
3Use of energy by moving object
If data is stored in intermediate buffer instead of higher-level storage, then bandwidth and power usage are reduced, but data access speed may decrease
Solution Approach 1:
The system changes the storage location parameter based on data reuse probability. For data unlikely to be reused soon, the system changes the storage parameter to use intermediate buffer instead of higher-level storage circuitry, thereby reducing bandwidth and power usage. For data with high reuse probability, the system maintains allocation in higher-level storage to preserve fast access speed. This conditional parameter change resolves the contradiction by applying the appropriate storage strategy based on data characteristics.
Solution Approach 2:
The intermediate buffer serves as an intermediary storage layer between lower-level memory and higher-level cache. When data is unlikely to be reused, the system uses the intermediate buffer as a stopping point, avoiding the need to allocate to higher-level storage. This intermediary approach allows the system to reduce energy consumption and bandwidth usage for non-reused data while maintaining the option to quickly promote frequently accessed data to higher-level storage, thus balancing energy efficiency and access speed.
Data Source
AI summary
An apparatus is provided for controlling the operating mode of control circuitry, such that the control circuitry may change between two operating modes. In an allocation mode, data that is loaded in response to an instruction is allocated into storage circuitry from an intermediate buffer, and the data is read from the storage circuitry. In a non-allocation mode, the data is not allocated to the storage circuitry, and is read directly from intermediate buffer. The control of the operating mode may be performed by mode control circuitry, and the mode may be changed in dependence on the type of instruction that calls the data, and whether the data may be used again in the near future, or whether it is expected to be used only once.