Memory Request Modulation via Dynamic Credit Control
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Solution Overview
Problem
The existing memory systems face challenges in managing memory requests efficiently, leading to bandwidth degradation and increased latency due to oversaturated request queues, which can result in poor performance and user dissatisfaction, especially when the credit-based communication scheme fails to control the flow of memory access requests effectively.
Innovation Solution
Implementing a credit-based system where the memory-side controller monitors the quantity of outstanding memory requests and modulates credit returns based on thresholds, preventing queue overflow and ensuring controlled communication flows between the host and memory devices, thereby maintaining bandwidth and latency performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the memory system allows high memory request throughput, then productivity is improved, but the request queues become oversaturated leading to bandwidth degradation and increased latency
Solution Approach 1:
The memory device implements a feedback mechanism by monitoring the quantity of outstanding memory requests in its request queues and dynamically modulating credit returns to the host device. When the queue depth exceeds a threshold, the memory device reduces credit returns to throttle incoming requests, preventing queue saturation and maintaining low latency while preserving high throughput capability.
2Ease of operation
If the credit-based communication scheme returns credits freely, then ease of operation is improved, but the memory device cannot control the flow of memory access requests effectively
Solution Approach 1:
The credit return mechanism transitions from a static, fixed protocol to a dynamic, adaptive system. The memory device adjusts credit return rates based on real-time monitoring of outstanding request quantities, enabling effective flow control while preserving the simplicity of the credit-based communication interface for the host device.
3Productivity
If the memory device processes more memory requests simultaneously, then productivity is improved, but device complexity increases due to queue management overhead
Solution Approach 1:
The memory device autonomously manages its request queues by self-monitoring the quantity of outstanding requests and self-regulating credit returns without requiring complex external control mechanisms. This self-service approach enables high processing capacity while keeping the control logic relatively simple and localized within the memory device.
Data Source
AI summary
Described apparatuses and methods enable a receiver of requests, such as a memory device, to modulate the arrival of future requests using a credit-based communication protocol. A transmitter of requests can be authorized to transmit a request responsive to possession of a credit corresponding to the communication request. In these situations, if the transmitter has exhausted a supply of credits, the transmitter waits until a credit is returned before transmitting another request. The receiver of the requests can manage credit returns based on whether a request queue has space to receive another request. Further, the receiver can delay a credit return based on how many requests are pending at the receiver, even if space is available in the request queue. This delay can prevent an oversupply of requests from developing downstream of the request queue. Latency, for instance, can be improved by managing the presence of requests that are downstream.