Write Buffer Unmapping During Flush Interrupts in Memory
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Solution Overview
Problem
The inefficiency in write performance of multi-level flash memory devices due to the slower write operations to main storage and the need for continuous background flush operations of the write buffer, which can be interrupted by new write commands, leading to reduced performance.
Innovation Solution
The implementation of a mechanism to suspend the write buffer flush operation and unmapping a portion of the write buffer using the last flushed address, allowing the host to send an unmap command and reuse the unmapped portion for new write commands, while resuming the flush operation when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a write buffer is used to improve write performance, then write speed is improved, but the buffer must be continuously flushed to main storage which reduces overall efficiency
Solution Approach 1:
The patent implements dynamic management of the write buffer by selectively unmapping flushed portions for reuse. The buffer transitions between mapped and unmapped states based on flush completion, allowing flexible reallocation of buffer space without waiting for complete flush operations. This dynamic state management resolves the contradiction by enabling both high-speed buffering and efficient throughput.
Solution Approach 2:
The patent recovers write buffer space by unmapping portions that have been flushed to main storage. Instead of waiting for the entire buffer to be flushed before reuse, the system discards the mapping of already-flushed portions and makes them available for new writes. This recovery mechanism eliminates the performance penalty of continuous flushing while maintaining buffer availability.
2Reliability
If the write buffer is flushed continuously to maintain data integrity, then data reliability is improved, but write performance deteriorates due to interruptions
Solution Approach 1:
The patent segments the write buffer management into distinct mapped and unmapped portions. The mapped portion contains data pending flush to main storage, while the unmapped portion is available for new writes. This segmentation allows the system to maintain data integrity for flushed portions while simultaneously accepting new writes in unmapped portions, eliminating performance interruptions.
Solution Approach 2:
The patent performs preliminary unmapping of buffer portions before they are needed for new writes. By unmapping flushed portions in advance, the system prepares reusable buffer space proactively, ensuring that new write operations can immediately utilize available buffer space without waiting for flush completion or causing performance interruptions.
3Reliability
If the entire write buffer is kept mapped to ensure data safety, then reliability is improved, but the buffer cannot be reused for new writes reducing productivity
Solution Approach 1:
The patent implements dynamic mapping and unmapping of write buffer portions based on their flush status. Mapped portions maintain data safety associations, while unmapped portions are freely reusable. This dynamic management resolves the contradiction by allowing the system to maintain reliability for active data while maximizing buffer utilization through reuse of flushed portions.
Solution Approach 2:
The patent recovers buffer space by discarding the mapping of flushed portions. Once data is safely transferred to main storage, the mapping is discarded and the buffer portion is recovered for new writes. This recovery process maintains data safety for flushed data while dramatically improving buffer utilization and overall system productivity.
4Speed
If the write buffer is used for fast writes, then write speed is improved, but buffer space is consumed quickly requiring frequent flushes
Solution Approach 1:
The patent recovers write buffer space by unmapping flushed portions, making them immediately available for new writes. This continuous recovery and reuse of buffer space extends the effective buffer lifetime, reducing the frequency of flush operations needed and minimizing time loss without sacrificing write speed performance.
Data Source
AI summary
Aspects relate to interrupting memory access during background operations of a memory device. In one example a memory device includes a memory controller to initiate a write buffer flush operation. A bus interface is coupled to a main memory and to a write buffer to receive a write command from a host during the write buffer flush operation. The memory controller initiates the write buffer flush operation, suspends the write buffer flush operation in response to the write command, sends a last flushed address of the write buffer from the memory device to the host through the bus interface, and unmaps a portion of the write buffer using the last flushed address.