Adaptive Memory Refresh Scheduling for Multi-Bank Latency Reduction
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Solution Overview
Problem
Existing memory systems face inefficiencies in bank refresh operations, leading to increased latency due to fixed spacing requirements and potential stalling of traffic during refresh cycles, which are not optimized for varying bank usage patterns.
Innovation Solution
Introduce adaptive refresh commands such as quad bank refresh (REFqb) and octa bank refresh (REFob) that allow flexible bank selection based on traffic patterns, enabling concurrent refresh of multiple banks without stalling, using additional information to specify addresses or skip distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed bank refresh commands are used, then all banks must be refreshed within the 64 ms window, but this causes traffic stalling and increased latency
Solution Approach 1:
The patent segments the bank refresh operation by introducing per-bank refresh commands that can individually target specific banks (bank 0 through bank 7) for refreshing. This allows the memory system to refresh only the necessary banks rather than all banks uniformly, thereby reducing the time banks are stalled and minimizing latency while ensuring reliable refresh completion for the targeted banks within the 64 ms window.
2Adaptability or versatility
If traditional refresh commands are used, then refresh operations must follow fixed patterns, but this reduces flexibility in arranging refresh operations
Solution Approach 1:
The patent introduces dynamic refresh command structures that allow the memory controller to adaptively select which banks to refresh and in what order, rather than following fixed refresh patterns. The per-bank refresh commands enable the system to dynamically adjust refresh scheduling based on traffic patterns and bank usage, improving both flexibility in arranging refresh operations and overall refresh performance by minimizing disruptions to active banks.
3Reliability
If all banks are refreshed uniformly, then refresh coverage is complete, but this causes unnecessary traffic stalling when not all banks need refreshing
Solution Approach 1:
The patent applies local quality by enabling selective refresh of individual banks based on their specific needs. The per-bank refresh commands allow the memory controller to identify which banks require refreshing and target only those banks, rather than uniformly refreshing all banks. This ensures adequate refresh coverage for active banks while avoiding unnecessary traffic stalling on banks that do not require refreshing, thereby improving memory operation efficiency.
Data Source
AI summary
A memory system with adaptive refresh commands is disclosed. In one aspect, a memory system or device that has multiple banks within a channel may receive a per bank command that indicates a first bank to be refreshed and provides additional information about a second bank to be refreshed. In a further exemplary aspect, a quad bank refresh command may be sent that indicates a first bank to be refreshed and provides additional information about second through fourth banks to be refreshed. In a further exemplary aspect, an octa bank refresh command may be sent that indicates a first bank to be refreshed and provides additional information about second through eighth banks to be refreshed. The three new refresh commands allow adjacent or spaced banks to be refreshed.