Memory Controller Write Acknowledgment for Cache Write Streaming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In integrated circuits, particularly in SoCs, write operations are stalled due to the need for write acknowledgments that confirm the completion of memory writes, which can disrupt write streaming and hinder performance due to the latency involved in lower level cache writes.
Innovation Solution
A memory controller is configured to send write acknowledgments contemporaneously with the scheduling of memory write requests, ensuring that write operations are acknowledged immediately upon scheduling, thereby reducing latency and allowing uninterrupted write streaming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system waits for write acknowledgments from lower level cache before processing subsequent write requests, then write coherence is maintained, but write streaming is disrupted and performance deteriorates
Solution Approach 1:
The memory controller sends write acknowledgments to the processor core contemporaneously with scheduling write requests on the memory pipeline, before the actual write completion is confirmed from lower level cache. This preliminary acknowledgment allows the processor core to continue streaming write requests without stalling, while write coherence is still maintained through the ordered processing guarantee of the memory pipeline.
2Reliability
If the system sends write acknowledgments only after actual write completion, then write coherence is ensured, but latency increases and write streaming is hindered
Solution Approach 1:
Write acknowledgments are sent in advance contemporaneously with request scheduling rather than waiting for actual write completion. The memory pipeline's inherent ordered processing guarantees that this preliminary acknowledgment does not compromise write coherence, thereby reducing latency and enabling continuous write streaming.
Solution Approach 2:
The system implements a feedback mechanism where the memory controller monitors the ordered processing state of the memory pipeline and sends acknowledgments based on scheduling position rather than completion status. This feedback approach allows the processor core to maintain write streaming while the memory controller ensures coherence through ordered processing tracking.
3Stability of the object's composition
If the processor core stalls waiting for write acknowledgments, then write order is maintained, but overall system throughput decreases
Solution Approach 1:
The memory controller provides preliminary write acknowledgments contemporaneously with scheduling write requests, allowing the processor core to maintain its write streaming without stalling. The memory pipeline's ordered processing ensures write order is preserved even though acknowledgments are sent before actual completion, thereby maintaining both write order and high system throughput.
Data Source
AI summary
In described examples, a processor system includes a processor core that generates memory write requests, a cache memory, and a memory controller. The memory controller has a memory pipeline. The memory controller is coupled to control the cache memory and communicatively coupled to the processor core. The memory controller is configured to receive the memory write requests from the processor core; schedule the memory write requests on the memory pipeline; and contemporaneously with scheduling respective ones of the memory write requests on the memory pipeline, send to the processor core a write acknowledgment confirming that writing of a data payload of the respective memory write request to the cache memory has completed.