SSD Controller Adaptive Response Time Management
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Solution Overview
Problem
Current solid-state drives (SSDs) lack the ability to optimally adjust response performance based on the type of I/O requests, leading to unnecessary best-effort responses and potential bottlenecks, which can result in inefficient resource utilization and power consumption.
Innovation Solution
The SSD includes a controller that determines response times and executes performance adjustment processes by utilizing idle times for block management and wear leveling, allowing it to adjust response performance based on notifications from the host, such as reducing parallel NAND accesses or executing garbage collection during idle periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the SSD processes all requests with best effort (maximum resource utilization), then response speed is improved, but power consumption increases and resource efficiency decreases
Solution Approach 1:
The patent applies dynamics by making the SSD's resource allocation flexible and adaptive rather than static. The controller dynamically adjusts the degree of parallelism in NAND access operations based on real-time conditions including I/O request patterns, queue depths, and power management requirements. This allows the system to optimize between response speed and power consumption by matching resource utilization to actual workload demands, avoiding unnecessary high-power operations during low-utilization periods
Solution Approach 2:
The patent changes operational parameters by adjusting the level of parallelism in NAND access operations. The controller can modify parameters such as the number of simultaneous read/write channels, buffer allocation sizes, and garbage collection timing based on workload characteristics. By varying these parameters according to I/O patterns and power state requirements, the system achieves efficient trade-offs between performance and energy consumption
2Productivity
If the SSD always uses maximum resources for request processing, then productivity is improved, but resource utilization efficiency deteriorates due to idle time waste
Solution Approach 1:
The patent implements continuity of useful action by ensuring that SSD resources remain productively engaged during periods between I/O requests. Instead of leaving resources idle, the controller utilizes available bandwidth and processing capacity to perform background maintenance operations such as wear leveling, garbage collection, and bad block management. This approach converts what would be wasted idle time into productive maintenance activities, improving overall resource utilization efficiency while maintaining request processing productivity
Solution Approach 2:
The patent applies preliminary action by proactively performing block management and wear leveling operations during idle periods before they are critically needed. The controller anticipates future maintenance requirements and schedules these operations during times when I/O demand is low, ensuring that the SSD remains in optimal condition for handling production workloads. This prevents performance degradation and extends device lifespan without impacting productivity
3Reliability
If the SSD executes block management during idle time, then reliability is improved, but response performance may be affected if not properly managed
Solution Approach 1:
The patent applies segmentation by dividing block management operations into discrete, manageable tasks that can be scheduled and executed independently during idle periods. Rather than performing large-scale maintenance operations that could monopolize resources, the controller breaks down wear leveling and garbage collection into smaller segments that can be interleaved with I/O request processing. This ensures that reliability-improving maintenance activities proceed without causing significant delays to response performance
Solution Approach 2:
The patent implements feedback mechanisms where the controller continuously monitors I/O queue depths, response times, and maintenance operation progress. Based on this feedback, the controller dynamically adjusts the scheduling and intensity of block management activities. When I/O demand increases, the controller automatically reduces or suspends maintenance operations to preserve response performance. When idle time is detected, the controller increases maintenance activity to improve reliability, creating a self-regulating system that balances both objectives
Data Source
AI summary
According to one embodiment, a storage device is accessible by an external device via an interface and includes a nonvolatile memory including one or more blocks, and a controller electrically connected to the nonvolatile memory. The controller receives from the external device a request and a notification indicating that a response performance of the request is to be lowered. In response to receiving the request and notification, the controller determines a response time longer than a processing time of the request, and executes a first performance lowering process that executes a block managing process of the nonvolatile memory by using an idle time which is a difference between the response time and the processing time of the request or executes a second performance lowering process that lowers the response performance so as to process the request by spending the response time.