Storage Bias Mode Switching for Cache Coherence and Access Locality
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Solution Overview
Problem
Existing storage devices supporting cache coherent interconnect protocols lack effective mechanisms for switching between host bias and device bias modes, leading to issues like stale data copies and inefficient data access.
Innovation Solution
Implementing a storage device with a bias mode management system that uses a locality counter, snoop filter, and look-ahead bias mode switching techniques to dynamically adjust between host bias and device bias modes based on access frequency, ensuring data coherence and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If host bias mode is used to allow host processor access to storage device memory, then data access flexibility is improved, but stale data copies may occur in device cache
Solution Approach 1:
The patent implements dynamic bias mode switching between host bias and device bias based on access patterns. The system transitions from static bias mode to dynamic adaptation using locality counters and snoop filters to detect access behavior and switch modes accordingly, resolving the contradiction between access flexibility and data coherence
Solution Approach 2:
The patent employs feedback mechanisms through snoop filters that monitor host processor accesses to device memory. When stale data is detected in device cache, the system receives feedback and switches from host bias to device bias mode, automatically correcting the coherence issue while maintaining operational flexibility
2Speed
If device bias mode is used to improve device access speed, then processing speed is improved, but host processor access efficiency deteriorates
Solution Approach 1:
The system dynamically switches between device bias mode (for fast device access) and host bias mode (for efficient host access) based on detected access patterns. This dynamic adaptation resolves the contradiction by optimizing for the active participant rather than maintaining a fixed bias
Solution Approach 2:
The patent implements periodic evaluation of access patterns through locality counters that track host and device accesses over time. This periodic monitoring enables the system to switch bias modes at appropriate intervals, balancing device access speed with host processor efficiency
3Productivity
If bias mode switching is implemented to optimize data access, then data access efficiency is improved, but device complexity increases
Solution Approach 1:
The patent implements self-service bias mode management where the storage device automatically monitors its own access patterns and switches bias modes without external host intervention. The locality counters and snoop filters enable the device to self-manage coherence, improving access efficiency while containing complexity within the device
Solution Approach 2:
The patent introduces intermediary structures (locality counters, snoop filters, and bias mode indicators) that mediate between host and device access. These intermediaries automate the complex decision-making process for bias mode selection, improving data access efficiency while isolating the complexity from the host processor
Data Source
AI summary
A storage device is disclosed. The storage device may include a storage for a data and a controller to manage access to the data in the storage. A mechanism may automatically manage a bias mode for a chunk of the data in the storage, the bias mode including one of a host bias mode and a device bias mode.