PCIe Multi-Stream Credit Allocation for Packet Flow Control

Solution Overview

Problem

Integrated circuits face challenges with packet overflow and routing congestion due to increasing bandwidth demands in high-speed data transfers, particularly in PCIe communications, leading to potential data loss and system instability.

Innovation Solution

Implementing multiple independent streams with credit checks in integrated circuits for both receivers and transmitters to manage packet flow dynamically, reducing congestion and overflow risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple independent streams with credit checks are implemented, then throughput and stability are improved, but device complexity increases

Engineering Contradiction:

ImprovethroughputVSAvoiddevice complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent divides the packet processing function into multiple independent streams (first stream, second stream, third stream, fourth stream), each handling different packet types or priorities. This segmentation allows parallel processing of packets, increasing throughput while managing complexity through modular design where each stream operates independently with its own credit checking mechanism.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic credit allocation where the number of credits allocated to each stream is not fixed but can be adjusted based on system conditions. The credit allocation mechanism dynamically responds to packet flow requirements, allowing the system to optimize throughput by reallocating credits to streams that need them most, while the dynamic nature helps manage complexity through adaptive control rather than static rigid allocation.

Inventive Principle:

Principle #15Dynamics

2Device complexity

If static routing techniques are used, then device complexity is reduced, but routing congestion increases

Engineering Contradiction:

Improvedevice complexityVSAvoidrouting efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent replaces static routing with dynamic routing decisions made at the credit checking stage. Instead of pre-determined fixed routing paths, the system dynamically determines which stream receives packets based on real-time credit availability and packet characteristics. This dynamic approach reduces routing congestion by adapting to current system state while maintaining manageable complexity through automated credit-based decision logic.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback mechanisms where the credit checking process continuously monitors packet flow and adjusts routing decisions based on observed conditions. The credit allocation system receives feedback about packet types, priorities, and flow patterns, and uses this information to dynamically adjust routing assignments. This feedback loop eliminates routing congestion by preventing overload in any single stream while keeping the system relatively simple through automated adaptive control.

Inventive Principle:

Principle #23Feedback

3Reliability

If credit allocation is dynamically adjusted, then packet overflow is reduced, but measurement and control complexity increases

Engineering Contradiction:

Improvepacket overflow preventionVSAvoidcontrol complexity

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent implements feedback mechanisms where the credit checking process continuously monitors packet flow and adjusts routing decisions based on observed conditions. The credit allocation system receives feedback about packet types, priorities, and flow patterns, and uses this information to dynamically adjust routing assignments. This feedback loop eliminates routing congestion by preventing overload in any single stream while keeping the system relatively simple through automated adaptive control.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The credit checking and allocation system operates autonomously, self-regulating packet distribution without external intervention. The system automatically detects packet characteristics, evaluates credit availability, and makes routing decisions independently. This self-service approach simplifies control complexity by eliminating the need for complex external management while effectively preventing packet overflow through autonomous adaptive credit allocation.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20250321917A1Dynamic Credit Allocation with Closed-Loop Feedback Integration

Publication Date: 2025.10.16 ALTERA CORP

AI summary

Systems, methods, and circuitry for supporting high speed data transfers across link partners that are coupled by a communication link, such as a Peripheral Component Interconnect Express (PCIe). More specifically, integrated circuits, such as field programmable gate arrays (FPGAs), in a receiver may include multiple streams that are coupled to an application main band to improve the throughput of buffering and providing received packets to an application. The multiple streams may be first in, first out (FIFO) buffers that include a credit check to limit the risk of packet overflow. In some embodiments, integrated circuits in a transmitter may include multiple streams that are coupled to transmission processing circuitry. The transmitter may include a dynamic credit allocation system that adjusts credit allocations among the streams based on credit consumption data and congestion metrics.