DRAM Rank Interleaving for Data and Metadata Access Overhead
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Solution Overview
Problem
Existing memory systems face inefficiencies in bandwidth utilization due to metadata operations, which primarily consist of partial writes, leading to substantial overhead and reduced efficiency in reading and writing data, especially when data and metadata are stored in the same memory array.
Innovation Solution
Implementing rank interleaving for data and metadata operations in a dynamic random access memory (DRAM) device, allowing metadata operations to overlap with data operations in different ranks, thereby reducing overhead and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metadata operations are performed sequentially with data operations in the same memory rank, then data integrity is maintained, but memory bandwidth utilization deteriorates due to substantial overhead from partial writes
Solution Approach 1:
The memory system is divided into multiple independent ranks, allowing metadata operations on one rank to be performed simultaneously with data operations on another rank. This segmentation enables parallel execution of operations that would otherwise be sequential, improving memory bandwidth utilization by eliminating the overhead of sequential metadata and data access.
Solution Approach 2:
The patent introduces a temporal dimension to metadata operations by storing metadata in a separate buffer register rather than immediately writing to memory. This allows metadata operations to be decoupled from data operations in time, enabling data to be read or written while metadata is prepared for subsequent writing, thereby improving overall memory bandwidth utilization.
2Quantity of substance
If data and metadata are stored in the same memory array, then storage efficiency is improved, but access efficiency deteriorates due to interference between data and metadata operations
Solution Approach 1:
The memory array is segmented into multiple ranks, with each rank capable of independent operation. Metadata is stored in dedicated buffer registers associated with each rank, allowing metadata operations to be isolated from data operations. This segmentation enables simultaneous data access and metadata updates without interference, maintaining high access efficiency while storing both data and metadata in the same physical memory array.
Solution Approach 2:
Buffer registers are introduced as intermediary storage elements between the memory array and the control logic. These buffers temporarily hold metadata before it is written to the memory array, allowing data operations to proceed independently without waiting for metadata operations to complete. This intermediary mechanism decouples data and metadata access paths, improving overall access efficiency.
3Reliability
If metadata operations are performed immediately after data operations, then cache coherence is maintained, but bandwidth overhead increases due to lack of operation overlap
Solution Approach 1:
Metadata is loaded into buffer registers in advance of being written to the memory array. This preliminary action allows data operations to complete while metadata is being prepared in the buffers, enabling overlap between data access and metadata preparation. The pre-loaded metadata is then written to memory in a subsequent step, maintaining cache coherence while improving bandwidth efficiency through operation overlap.
Solution Approach 2:
The memory system maintains continuous useful action by allowing data operations to proceed while metadata operations are being prepared in parallel in buffer registers. This continuity eliminates idle periods where the memory subsystem would otherwise be waiting for metadata operations to complete before proceeding with data operations, thereby improving bandwidth efficiency while maintaining cache coherence through proper ordering of operations.
Data Source
AI summary
This disclosure provides systems, methods, and devices for memory systems that support processing data and metadata within a memory of a memory device. In a first aspect, a method of controlling a memory device includes executing a first request in a first rank of the memory device during a first time period, wherein the first time period comprises a first data access portion and a first metadata access portion; and executing a second request in a second rank of the memory device during a second time period, wherein the second time period comprises a second data access portion and a second metadata access portion, wherein executing the first request in the first rank and executing the second request in the second rank comprises interleaving the first request and the second request between the first rank and the second rank. Other aspects and features are also claimed and described.