Memory-Aware Cache Bypassing for Low-Latency, Lower-Power Access
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Solution Overview
Problem
Computing systems face operational inefficiencies due to architectural limitations, particularly in data retrieval latency and storage capacity trade-offs in memory sub-systems, which are exacerbated by slower external communication buses and power consumption from activating memory pages.
Innovation Solution
Implementing a memory sub-system with processor-side and memory-side controllers that manage caching and pre-fetching based on memory array state information, including activation states and access patterns, to selectively enable or disable data storage in lower memory levels, thereby optimizing data access and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data is pre-fetched to lower memory levels (cache), then data access speed is improved, but power consumption increases due to memory page activations
Solution Approach 1:
The system performs preliminary actions by pre-fetching data to lower memory levels before actual access is needed. The memory controller monitors access patterns and proactively loads data into cache memory, reducing future access latency while managing power consumption through selective pre-fetching based on predicted access needs
Solution Approach 2:
The system dynamically adjusts pre-fetching behavior based on real-time memory access patterns and power state information. The memory controller modifies pre-fetching aggressiveness according to current workload characteristics and power consumption constraints, enabling adaptive optimization of the speed-power tradeoff
2Loss of time
If cache memory is used to store data, then data retrieval latency is reduced, but storage capacity is limited
Solution Approach 1:
The memory hierarchy is segmented into multiple levels (cache memory, buffer memory, and main memory array), with each segment serving specific functions. Cache memory provides fast access for frequently accessed data, while buffer memory and memory array provide additional storage capacity, collectively resolving the latency-capacity tradeoff through hierarchical organization
Solution Approach 2:
The patent implements a nested memory hierarchy where cache memory is nested within the memory controller, which is itself nested within the broader memory sub-system. This nested structure allows small, fast cache memory to be contained within larger, slower memory arrays, enabling the system to achieve both fast access times and large storage capacity simultaneously
3Speed
If memory pages are activated for data storage, then access speed is improved, but power consumption increases
Solution Approach 1:
The system changes the power state parameter of memory pages based on access patterns and timing. Memory pages are activated (awakened from sleep state) only when data is predicted to be accessed, and deactivated (returned to sleep state) when not needed, dynamically adjusting the power consumption parameter while maintaining access speed when required
4Productivity
If pre-fetching is enabled to improve operational efficiency, then productivity is improved, but power consumption increases
Solution Approach 1:
The memory controller implements feedback mechanisms that monitor actual memory access patterns and compare them against pre-fetching predictions. Based on this feedback, the system adjusts pre-fetching behavior to improve operational efficiency while avoiding unnecessary pre-fetching operations that would waste power, creating a self-regulating system that optimizes the productivity-power tradeoff
Data Source
AI summary
Systems, apparatuses, and methods for memory management are described. For example, these may include a first memory level including memory pages in a memory array, a second memory level including a cache, a pre-fetch buffer, or both, and a memory controller that determines state information associated with a memory page in the memory array targeted by a memory access request. The state information may include a first parameter indicative of a current activation state of the memory page and a second parameter indicative of statistical likelihood (e.g., confidence) that a subsequent memory access request will target the memory page. The memory controller may disable storage of data associated with the memory page in the second memory level when the first parameter associated with the memory page indicates that the memory page is activated and the second parameter associated with the memory page is greater than or equal to a threshold.