User-Space Packet Queue Handoff Before Thread Preemption

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Solution Overview

Problem

Existing queue processing techniques in user-space packet processing suffer from inefficiencies due to thread preemption, leading to suboptimal throughput, packet reordering, and processor under/over-utilization, especially when using kernel bypass applications.

Innovation Solution

A queue management system transfers queue handling from a first thread to a second thread on a different processor before preemption occurs, using a queue access manager to identify imminent preemption and set flags, ensuring continuous packet processing by balancing load across multiple processors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If user-space packet processing uses traditional queue access techniques, then implementation is simple, but thread preemption causes packet processing delays and reduces throughput

Engineering Contradiction:

Improvepacket processing throughputVSAvoidpacket processing delay

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by transferring queue ownership to a different thread before preemption occurs. The queue access manager detects imminent preemption and initiates the transfer in advance, ensuring that when preemption happens, another thread is already ready to continue packet processing without delay. This eliminates the stop-start nature of traditional preemption and maintains continuous throughput.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A queue access manager acts as an intermediary between the preempted thread and the queue. This manager coordinates the transfer of queue ownership, manages the preemption flag, and ensures smooth handoff of packet processing responsibilities. The intermediary mechanism allows preemption to occur without breaking the packet processing flow, as the manager orchestrates the transition between threads.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If queue handling continues on the same thread during preemption, then implementation is simple, but processor utilization becomes suboptimal and packet reordering occurs

Engineering Contradiction:

Improveprocessor utilizationVSAvoidpacket processing reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system dynamically assigns queue ownership based on thread availability and preemption status. Instead of static thread-to-queue binding, the queue access manager dynamically transfers queue ownership to threads that are not preempted. This dynamic reassignment optimizes processor utilization by ensuring active threads handle queues while maintaining packet processing reliability through proper ownership tracking and synchronization.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The queue access manager uses feedback from the preemption flag and thread state to determine when and how to transfer queue ownership. The system continuously monitors thread preemption status and adjusts queue assignment accordingly, ensuring that queues are transferred to appropriate threads based on real-time system state. This feedback mechanism prevents packet reordering by maintaining correct processing order across thread boundaries.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If preemption is allowed for thread scheduling, then system flexibility improves, but queue processing is interrupted and throughput decreases

Engineering Contradiction:

Improvethread scheduling flexibilityVSAvoidpacket processing throughput

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The system performs preliminary transfer of queue ownership before preemption occurs. The queue access manager detects that a thread is about to be preempted and initiates the transfer to another thread in advance. This preliminary action allows the preempted thread to be replaced smoothly, maintaining throughput while preserving scheduling flexibility. The transfer happens proactively rather than reactively, eliminating the interruption that would otherwise occur at preemption boundaries.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12579083B2Efficient queue access for user-space packet processing

Publication Date: 2026.03.17 RED HAT LLC

AI summary

An example method may include determining whether a preemption flag associated with a first input/output (I/O) handling thread is equal to a first value indicating that preemption of the first I/O queue handling thread is forthcoming, wherein the first I/O queue handling thread is executing on a first processor, the first I/O queue handling thread is associated with a first set of one or more queue identifiers, and each queue identifier identifies a queue being handled by the first I/O queue handling thread, and, responsive to determining that the preemption flag is equal to the first value, transferring the first set of one or more queue identifiers to a second I/O queue handling thread executing on a second processor. Transferring the first set of queue identifiers may include removing the one or more queue identifiers from the first set.