Memory Command Scheduler Latency Prediction
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Solution Overview
Problem
Variations in memory command latencies across different memory locations and types in computer systems lead to inefficient scheduling and execution, with high-latency write commands often blocking critical read commands, affecting overall system performance.
Innovation Solution
Implementing a command scheduler that predicts latency for memory commands based on memory addresses, types, and operating modes, and prioritizes them in a queue to expedite higher-latency or priority commands, while delaying high-latency write commands until conditions are met to avoid blocking read operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If memory commands are processed in the order they are received, then the scheduling is simple, but high-latency write commands block critical read commands causing inefficiency
Solution Approach 1:
The command scheduler dynamically adjusts the processing order of memory commands based on real-time latency predictions and command priorities. Instead of a static first-come-first-served approach, the system continuously evaluates command characteristics and reorders execution to optimize performance, allowing high-priority read commands to bypass lower-priority write commands when necessary.
Solution Approach 2:
The system performs preliminary latency prediction for each memory command before it is fully processed. By predicting the latency of upcoming commands in advance, the scheduler can proactively reorder the command queue to prevent high-latency write commands from blocking critical read commands, rather than reacting after the blocking has already occurred.
2Reliability
If high-latency write commands are executed immediately, then the write operations are completed, but critical read commands are blocked causing increased system latency
Solution Approach 1:
The command scheduler acts as an intermediary between write commands and the memory subsystem. It intercepts incoming write commands, evaluates their potential to block read operations, and mediates their execution timing. When a write command is predicted to cause significant blocking, the scheduler delays its execution until it is safe to proceed, thereby protecting critical read operations from latency penalties.
Solution Approach 2:
The system applies preliminary anti-action by predicting and preventing the harmful effect of write command blocking before it occurs. Through latency prediction and priority evaluation, the scheduler identifies write commands that are likely to block critical reads and takes preventive measures by reordering or delaying their execution, thus counteracting the potential harm before it impacts system performance.
3Productivity
If memory commands are reordered based on latency prediction, then system performance is improved, but the scheduling mechanism becomes more complex
Solution Approach 1:
The command scheduling system performs self-service by autonomously evaluating command latencies and making reordering decisions without external intervention. The latency prediction mechanism and priority evaluation are integrated into the scheduler itself, allowing it to automatically adapt to varying memory conditions and command characteristics, thereby managing its own complexity while delivering performance improvements.
Solution Approach 2:
The system incorporates feedback mechanisms where the actual execution outcomes of memory commands are used to refine future latency predictions. By continuously learning from past performance data, the scheduler improves its prediction accuracy over time, which justifies the initial complexity investment by delivering progressively better performance optimization with minimal additional overhead.
Data Source
AI summary
The disclosed embodiments provide a system for processing a memory command on a computer system. During operation, a command scheduler executing on a memory controller of the computer system obtains a predicted latency of the memory command based on a memory address to be accessed by the memory command. Next, the command scheduler orders the memory command with other memory commands in a command queue for subsequent processing by a memory resource on the computer system based on the predicted latency of the memory command.