Domain-Specific IOMMU Command Buffers for Parallel Invalidation

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Solution Overview

Problem

In complex computer systems with numerous peripherals, IOMMU command transactions become inefficient due to high overhead and spin/lock conditions caused by the number of memory accesses required for invalidation and ordering rules, leading to wasted CPU cycles.

Innovation Solution

Implementing domain-specific command buffers within the IOMMU system allows parallel processing of commands for different domains, reducing inefficiency by minimizing spin/lock conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single command buffer is used for IOMMU command processing, then the system structure remains simple, but spin/lock conditions increase and system performance deteriorates

Engineering Contradiction:

ImproveIOMMU command buffer structureVSAvoidcommand processing throughput

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent divides the single command buffer into multiple domain-specific command buffers, where each buffer is associated with a specific domain. This segmentation allows parallel processing of commands from different domains, eliminating spin/lock conditions while maintaining manageable system complexity through organized separation of command streams.

Inventive Principle:

Principle #1Segmentation

2Productivity

If multiple domain-specific command buffers are implemented, then parallel command processing improves, but device complexity increases

Engineering Contradiction:

Improvecommand processing throughputVSAvoidIOMMU command buffer structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements a universal command buffer interface that can handle multiple domain-specific buffers through a standardized mechanism. The IOMMU is designed to process commands from any domain-specific buffer using a common validation and execution path, allowing parallel processing without proportionally increasing overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Loss of time

If domain-specific command buffers are used, then spin/lock conditions are reduced, but memory access overhead increases

Engineering Contradiction:

Improvespin/lock cycle timeVSAvoidmemory access overhead

Core Design Contradiction:

Loss of timeVSUse of energy by moving object

Solution Approach 1:

The patent performs preliminary validation of commands at the domain-specific buffer level before they are submitted to the IOMMU. This pre-validation ensures that commands are properly formatted and authorized before memory access occurs, reducing the need for re-validation and minimizing overall memory access overhead while maintaining the benefits of reduced spin/lock conditions.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250390437A1Scalable input/output memory management unit (IOMMU) command processing

Publication Date: 2025.12.25 ADVANCED MICRO DEVICES INC

AI summary

A data processing system includes an input-output memory management unit (IOMMU) system. The IOMMU system includes a plurality of domain-specific command buffers in which each domain-specific command buffer is associated with a different one of a plurality of domains, and an IOMMU block that caches translations of each of the plurality of domains and controls the translations of each of the plurality of domains responsive to at least one command received from a corresponding domain-specific command buffer.