Predictive Control Page Loading for Flash Storage Latency
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Solution Overview
Problem
Flash storage devices experience low input/output operations per second (IOPS) and random performance issues due to frequent foreground loading of control information from non-volatile memory, especially in low queue depth environments, which increases latency and reduces available bandwidth.
Innovation Solution
The storage device predicts control pages based on identified patterns from previous read commands, allowing predicted control pages to be loaded in the background while data is being read for previous commands, thereby reducing foreground loading and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control information is loaded from non-volatile memory for every read command, then data can be retrieved accurately, but latency increases and IOPS decreases
Solution Approach 1:
The system performs preliminary actions by identifying and loading control information for future read commands before they are actually executed. The controller analyzes the read command queue, predicts which control pages will be needed, and loads them into the cache in advance, thereby reducing latency when the actual read commands are executed.
Solution Approach 2:
The system dynamically adjusts the loading strategy based on queue depth conditions. When queue depth is low (below threshold), the controller activates the pattern tracking and predictive loading mechanism. When queue depth is high, the system switches to traditional loading methods, making the system adaptive to different operational conditions.
2Productivity
If cache size is increased to store control information, then foreground loading is reduced and performance improves, but device cost increases
Solution Approach 1:
Instead of simply increasing cache size, the system performs preliminary analysis of the read command queue to identify patterns and predict which control pages will be needed. This allows the system to proactively load only the necessary control information into the cache, maximizing cache utilization efficiency without requiring additional cache capacity.
Solution Approach 2:
The system changes the operational parameters of the cache by implementing a predictive loading algorithm that dynamically determines which control pages to load based on queue depth and access patterns. This transforms the cache from a passive storage buffer into an actively managed predictive cache, improving performance without increasing physical size.
3Ease of operation
If queue depth is kept low to simplify command processing, then command execution is straightforward, but control information loading frequently occurs in foreground reducing bandwidth
Solution Approach 1:
The system performs preliminary identification of control pages needed for future read commands. By analyzing the queue structure and predicting access patterns, the controller loads control information in advance during background operations, preventing frequent foreground loading and maintaining bandwidth availability.
Solution Approach 2:
The system introduces an intermediary predictive mechanism between the read command queue and the control information loading process. This intermediary layer analyzes queue patterns and mediates the loading timing, allowing low queue depth operation while preventing bandwidth consumption through intelligent predictive pre-loading.
Data Source
AI summary
Aspects of a storage device are provided which allow for identification of control page patterns from previous read commands and prediction of control pages to load in advance for subsequent read commands. The storage device includes a memory configured to store data and a plurality of control pages. Each of the control pages includes a plurality of logical addresses associated with the data. A controller is configured to receive from a host device a plurality of read commands associated with a sequence of the control pages. The controller is further configured to identify and store a control page pattern based on the sequence of control pages and to predict one or more of the control pages from one or more of the other control pages in the sequence in a subsequent plurality of read commands.