Memory Controller Throttling Delay for Write Latency
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Solution Overview
Problem
In memory systems, write operations often experience high latency spikes due to mismatched host data transfer rates and memory device write rates, leading to inefficient data accumulation and increased command latency, which affects the quality of service (QoS) by causing undesirable individual write latencies.
Innovation Solution
A memory system and method that incorporate a controller to manage data transfer by introducing a throttling delay based on the time elapsed since previous data transfer and the size of buffered data, ensuring the host data transfer rate aligns with the memory device write rate, thereby optimizing buffer allocation and reducing command latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the host data transfer rate is higher than the memory device write rate, then data transfer speed is improved, but command latency increases due to inefficient data accumulation
Solution Approach 1:
A buffer is introduced as an intermediary component between the host interface and the memory device. The buffer temporarily stores incoming host data at different rates, decoupling the host data transfer rate from the memory device write rate. This allows the host to transfer data at high speed while the memory device writes at its own pace, preventing latency spikes by smoothing out rate mismatches.
Solution Approach 2:
The system dynamically adjusts the buffer allocation parameters based on the elapsed time since the previous write operation and the current buffer data size. By changing the buffer management parameters (such as buffer size allocation and timing) according to actual operating conditions, the system optimizes the balance between data transfer speed and command latency, preventing both data loss and excessive latency.
2Productivity
If buffer allocation is performed without throttling delay, then data processing efficiency is improved, but latency spikes occur due to rate mismatch
Solution Approach 1:
The system implements periodic buffer allocation with a throttling delay that is determined based on the elapsed time since the previous write operation. This periodic action with controlled timing prevents continuous buffer allocation that would cause latency spikes, while still maintaining high data processing efficiency by allocating buffers at optimal intervals.
Solution Approach 2:
The buffer allocation process incorporates feedback by monitoring the elapsed time since the previous write operation and the current buffer data size. Based on this feedback information, the system dynamically determines the appropriate throttling delay, creating a closed-loop control system that adapts to varying data transfer patterns and prevents latency spikes while maintaining efficiency.
3Productivity
If the host data transfer rate does not align with the memory device write rate, then data accumulation efficiency is improved, but QoS deteriorates due to undesirable individual write latencies
Solution Approach 1:
The buffer serves as a mediator that decouples the host data transfer rate from the memory device write rate, allowing data accumulation at high efficiency while maintaining consistent QoS. The buffer absorbs rate variations and ensures that individual write operations complete within expected timeframes, preventing QoS deterioration despite rate mismatches.
Solution Approach 2:
The system dynamically changes buffer management parameters based on the elapsed time since the previous write operation and the current buffer data size. This parameter adjustment optimizes data accumulation efficiency while ensuring that individual write latencies remain within acceptable ranges, thereby maintaining high QoS despite variations in host data transfer rates.
Data Source
AI summary
A memory system includes a memory device and a controller. The controller receives data from a host, allocates buffers after a throttling delay, buffers the data in the buffers, provides the buffered data to the memory device for a write operation, generates a response associated with the write operation, and transmits the response to the host. The controller inserts a throttling delay before allocating the buffers and/or transmitting the response. The throttling delay is determined based on a time elapsed since providing previously buffered data to the memory device and the size of the buffered data. The throttling delay is corrected based on the difference of the number of currently allocated buffers and a buffer reserve threshold.