SSD Controller Deadline-Based Command Scheduling

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Solution Overview

Problem

Current solid state drives (SSDs) face challenges in reducing power consumption, especially in portable devices, as they often operate at full power even when not needed, leading to increased energy usage and heat generation.

Innovation Solution

Implementing a controller that schedules command processing based on designated deadline times, allowing the SSD to transition to low power states when not required for immediate operation, thereby reducing power consumption and improving Quality of Service (QoS) by optimizing resource allocation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the SSD processes all command requests with great effort to complete as fast as possible, then the productivity and response time are improved, but the power consumption increases

Engineering Contradiction:

Improvecommand processing speedVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The SSD dynamically adjusts its processing mode between best-effort processing and deadline-based processing. The controller monitors command queue status and host activity patterns, switching between processing strategies to optimize the balance between productivity and power consumption based on real-time conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the processing parameter from continuous best-effort execution to scheduled deadline-based execution. By introducing deadline parameters and scheduling intervals, the SSD can control when processing occurs, allowing it to enter low-power states between processing intervals while still meeting performance requirements.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If the SSD enters low power consumption state after idle period, then the power consumption is reduced, but the response time to new commands increases

Engineering Contradiction:

Improvepower consumptionVSAvoidresponse time

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The SSD performs preliminary actions by processing commands according to deadlines before entering low-power states. The controller schedules and completes time-critical operations in advance, ensuring that when the SSD transitions to low-power mode, no urgent commands are pending, thus minimizing response time penalties upon wake-up.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the host and command queue status to determine optimal timing for entering and exiting low-power states. The controller monitors command submission patterns and adjusts its power state transitions dynamically, reducing response time delays by anticipating when the host will issue new commands.

Inventive Principle:

Principle #23Feedback

3Reliability

If the SSD operates at full power continuously, then the reliability and performance are maintained, but the lifespan is reduced due to increased wear

Engineering Contradiction:

Improveperformance consistencyVSAvoidSSD lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The SSD implements periodic action by alternating between active processing periods and low-power idle periods based on command deadlines and host activity. This periodic operation pattern reduces cumulative wear on flash memory cells and other components while maintaining performance reliability during active periods, thereby extending overall device lifespan.

Inventive Principle:

Principle #19Periodic action

4Use of energy by moving object

If the SSD schedules commands based on deadline times, then the power consumption is reduced and QoS is improved, but the device complexity increases

Engineering Contradiction:

Improvepower consumptionVSAvoidcontroller complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The controller architecture is segmented into distinct functional modules: a command scheduling module that handles deadline-based prioritization, a power management module that controls state transitions, and a processing engine that executes commands. This segmentation allows each module to perform its function independently, reducing overall controller complexity while enabling sophisticated deadline-based scheduling and power management.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11520496B2Electronic device, computer system, and control method

Publication Date: 2022.12.06 KIOXIA CORP

AI summary

According to one embodiment, an electronic device connectable to a host via an interface includes a nonvolatile memory and a controller electrically connected to the nonvolatile memory and capable of processing commands issued by the host in parallel. When the electronic device is connected to the host, the controller determines, when one or more commands to be processed by one or more deadline times, respectively, are issued by the host, scheduling indicative of timings at which the one or more commands are processed, respectively, based on the one or more deadline times. The controller performs processing corresponding to the one or more commands in accordance with the scheduling.