Memory Controller Read Recovery Latency Reduction
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Solution Overview
Problem
Existing read recovery algorithms in storage devices experience significant latency due to the sequential nature of read operations, leading to delays in queued read operations and deteriorated system performance.
Innovation Solution
A new operation method for a memory controller that includes performing a hard decoding-based read recovery operation, determining if a second read command is queued, and temporarily stopping the read recovery if a queued command exists, allowing for immediate processing of the queued command without waiting for the completion of the soft decoding-based read recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sequential read recovery algorithm (hard decoding followed by soft decoding) is implemented, then the recovery probability is improved, but the recovery time increases significantly causing latency
Solution Approach 1:
The patent implements a dynamic read recovery algorithm that adaptively selects between hard decoding and soft decoding based on real-time conditions. The controller determines whether to perform soft decoding by evaluating factors such as the number of failed read operations, current system load, and queue status. This dynamic approach allows the system to use the faster hard decoding when sufficient and reserve soft decoding for cases where it's truly necessary, thereby improving recovery probability while minimizing recovery time.
Solution Approach 2:
The patent changes the operational parameters of the read recovery process by introducing conditional execution of soft decoding. Instead of always performing the complete hard decoding followed by soft decoding sequence, the system modifies the recovery process parameters by selectively enabling or disabling soft decoding based on predetermined conditions. This parameter change allows the system to optimize between recovery probability and recovery time by adjusting the depth of the recovery algorithm executed.
2Reliability
If the read recovery operation is performed to completion before processing queued commands, then the current read operation is recovered, but the latency for queued read operations increases
Solution Approach 1:
The patent applies preliminary action by checking the status of the read command queue before committing to a complete soft decoding recovery process. The controller preliminarily evaluates whether queued commands are present and determines the appropriate recovery strategy in advance. This preliminary assessment allows the system to interrupt lengthy soft decoding operations when queue conditions warrant prioritizing other read commands, thus maintaining system productivity while still achieving necessary recoveries.
Solution Approach 2:
The patent implements dynamic control of the read recovery process by continuously monitoring queue status and adjusting the recovery execution accordingly. When queued commands are detected, the system dynamically interrupts the current soft decoding operation and processes the queue instead. This dynamic behavior allows the system to balance between completing current recoveries and maintaining overall system throughput, preventing excessive latency for queued operations.
Data Source
AI summary
Provided is an operation method of a memory controller which includes obtaining first read data from a second external device based on a first read command received from a first external device and performing error correction and decoding on the first read data to determine whether reading is successful or unsuccessful, performing a hard decoding-based read recovery operation and a soft decoding-based read recovery operation when a read failure occurs as a result of the first read operation, determining whether there is a second read command queued when the hard decoding-based read recovery has failed, temporarily stopping the read recovery operation for the first read data when there is the second read command queued and obtaining second read data by reading data from the second external device based on the second read command and performing error correction and decoding on the second read data.