Speculative Readout Mode for Flash Memory Caching

Solution Overview

Problem

In SSD-based storage systems, speculative prefetching is inefficient due to size mismatch between data chunks and storage pages, leading to increased power consumption and latency, as each chunk request results in retrieving an entire page, even when multiple chunks are within the same page, causing redundant operations and reduced battery life.

Innovation Solution

Implementing a speculative readout mode where the storage device retrieves and caches entire pages containing requested data units, allowing subsequent requests to read from the cached page without re-reading from the SSD, and aligning data storage to page boundaries to optimize prefetching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the storage device retrieves an entire storage page for each data unit request, then the data access rate is improved, but the power consumption increases due to redundant read operations

Engineering Contradiction:

Improvedata access rateVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The storage device performs preliminary action by retrieving and caching the entire storage page in volatile memory before subsequent data unit requests arrive. When a data unit is requested, the page is already available in the cache, eliminating the need for repeated read operations from the slower non-volatile memory. This preliminary caching action resolves the contradiction by ensuring fast access (improving speed) while avoiding redundant power-consuming read operations from the storage medium.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The speculative readout mode enables continuity of useful action by maintaining the storage page in the volatile memory cache for multiple consecutive data unit requests. Instead of repeatedly accessing the non-volatile memory for each data unit, the system continuously serves requests from the cached page, eliminating idle time and redundant operations. This continuous service from cache improves data access rate while minimizing power consumption.

Inventive Principle:

Principle #20Continuity of useful action

2Speed

If the storage device retrieves an entire storage page for each data unit request, then the data access rate is improved, but the latency increases due to redundant read operations

Engineering Contradiction:

Improvedata access rateVSAvoidlatency

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The storage device performs preliminary action by retrieving and caching the entire storage page in volatile memory before subsequent data unit requests arrive. When a data unit is requested, the page is already available in the cache, eliminating the need for repeated read operations from the slower non-volatile memory. This preliminary caching action resolves the contradiction by ensuring fast access (improving speed) while avoiding redundant power-consuming read operations from the storage medium.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The speculative readout mode enables continuity of useful action by maintaining the storage page in the volatile memory cache for multiple consecutive data unit requests. Instead of repeatedly accessing the non-volatile memory for each data unit, the system continuously serves requests from the cached page, eliminating idle time and redundant operations. This continuous service from cache improves data access rate while minimizing power consumption.

Inventive Principle:

Principle #20Continuity of useful action

3Loss of time

If the storage device caches entire storage pages, then the reading latency is improved for subsequent requests, but the device complexity increases

Engineering Contradiction:

Improvereading latencyVSAvoiddevice complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The storage device performs preliminary action by retrieving and caching the entire storage page in volatile memory before subsequent data unit requests arrive. When a data unit is requested, the page is already available in the cache, eliminating the need for repeated read operations from the slower non-volatile memory. This preliminary caching action resolves the contradiction by ensuring fast access (improving speed) while avoiding redundant power-consuming read operations from the storage medium.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The speculative readout mode enables continuity of useful action by maintaining the storage page in the volatile memory cache for multiple consecutive data unit requests. Instead of repeatedly accessing the non-volatile memory for each data unit, the system continuously serves requests from the cached page, eliminating idle time and redundant operations. This continuous service from cache improves data access rate while minimizing power consumption.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS9582204B2Speculative prefetching of data stored in flash memory

Publication Date: 2017.02.28 APPLE INC

AI summary

A method for data storage, includes holding a definition of a speculative readout mode for readout in a storage device, in which the storage device is requested to read a data unit having a data unit size, and in response the storage device retrieves a storage page that contains the data unit and has a storage page size larger than the data unit size, and retains the storage page in preparation for subsequent requests. Activation of the speculative readout mode is coordinated. A readout command using the speculative readout mode is performed.