Hybrid Memory System DRAM Cache Nonvolatile Segmentation

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Solution Overview

Problem

The increasing power consumption and limitations in long-term bit growth of dynamic random access memory (DRAM) pose challenges, particularly in managing volatile data and ensuring data integrity, as traditional DRAM systems face issues with standby power consumption and the feasibility of continuous bit growth.

Innovation Solution

A hybrid memory system is introduced, comprising a central processing unit, a storage device, and a main memory that includes both volatile and nonvolatile memory, where data is selectively loaded into either memory type based on its read-only or read-write properties, with a cache allocation mechanism to optimize data management and migration between DRAM and nonvolatile memory like PRAM, ensuring efficient use of both memory types.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If volatile DRAM capacity is increased to meet growing data storage needs, then memory capacity is improved, but power consumption (especially standby power) increases

Engineering Contradiction:

Improvememory capacityVSAvoidpower consumption

Core Design Contradiction:

Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The memory system is segmented into volatile DRAM and nonvolatile memory (NVM) regions. The DRAM is divided into cache areas for frequently accessed data and main memory areas, while NVM stores less frequently accessed data. This segmentation allows the system to reduce overall power consumption by keeping only essential data in power-hungry DRAM.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different memory regions are assigned different volatility characteristics based on local quality requirements. Frequently accessed data resides in volatile DRAM for fast access, while less frequently accessed data is stored in nonvolatile memory. The system dynamically manages data placement based on access patterns, ensuring that only necessary portions of memory consume power.

Inventive Principle:

Principle #3Local quality

2Speed

If volatile DRAM is used for fast data access, then access speed is improved, but data loss occurs when power is interrupted

Engineering Contradiction:

Improvedata access speedVSAvoiddata integrity

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

A hybrid memory management mechanism acts as an intermediary between volatile DRAM and nonvolatile memory. This mechanism includes a memory management unit that monitors data in DRAM and automatically migrates less frequently accessed data to NVM. The system uses a hybrid page table to track data locations across both memory types, ensuring seamless access while maintaining data integrity through nonvolatile storage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary actions by proactively migrating data from DRAM to NVM based on access pattern analysis before power interruption occurs. The memory management unit continuously monitors data access frequencies and pre-migrates cold data to nonvolatile memory, ensuring data is preserved before any potential power loss event.

Inventive Principle:

Principle #10Preliminary action

3Use of energy by moving object

If nonvolatile memory is used to reduce power consumption, then power efficiency is improved, but data access speed decreases

Engineering Contradiction:

Improvepower efficiencyVSAvoiddata access speed

Core Design Contradiction:

Use of energy by moving objectVSSpeed

Solution Approach 1:

The system extracts frequently accessed data from nonvolatile memory and places it in volatile DRAM cache areas. The hybrid memory management mechanism identifies hot data through access pattern analysis and selectively loads it into DRAM, ensuring that only data requiring fast access resides in the high-speed volatile memory, while the majority of data remains in power-efficient NVM.

Inventive Principle:

Principle #2Taking out (Extraction)

4Use of energy by moving object

If hybrid memory management is implemented to optimize data placement, then power consumption is reduced, but system complexity increases

Engineering Contradiction:

Improvepower consumptionVSAvoidmemory management complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The hybrid memory management unit performs multiple functions including data migration, access pattern analysis, and memory address translation across both volatile and nonvolatile regions. This multi-functional approach consolidates complex management tasks into a single integrated mechanism, reducing the overall system complexity despite the heterogeneous memory architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8938601B2Hybrid memory system having a volatile memory with cache and method of managing the same

Publication Date: 2015.01.20 SAMSUNG ELECTRONICS CO LTD

AI summary

A hybrid memory system includes a central processing unit, a storage device configured to store user data and code data, and a main memory including a volatile memory and a nonvolatile memory, the main memory being configured to receive data necessary to perform an operation of the central processing unit from the storage device and to store the data, a part of the volatile memory being allocated for a cache for data stored in the nonvolatile memory.