Single-Producer Single-Consumer Ring Buffer HOL Blocking
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Solution Overview
Problem
In modern computing networks, zero-copy schemes can introduce head-of-line (HOL) blocking issues, leading to resource underutilization, particularly when slower virtualized services like deep packet inspection coexist with faster services, causing slower functions to occupy descriptors and starve faster functions.
Innovation Solution
Implementing a non-blocking zero-copy scheme that dynamically manages single-producer and single-consumer rings by allowing consumers to immediately return descriptors without returning data buffers, enabling producers to reuse buffers and avoid HOL blocking, thus improving system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If zero-copy schemes are used to improve data processing efficiency, then resource utilization improves, but head-of-line blocking occurs causing slower virtualized services to occupy descriptors and starve faster services
Solution Approach 1:
The patent segments the ring buffer management into separate producer and consumer operations with independent descriptor and data buffer management. Each service can enqueue descriptors and dequeue data buffers independently, preventing one service from blocking another. The ring buffer is divided into descriptor entries and data buffer regions, allowing decoupled management of metadata and actual data.
Solution Approach 2:
The patent implements dynamic buffer management where the number of in-flight buffers can be adjusted based on service requirements. Faster services can have larger buffer allocations while slower services use smaller allocations, allowing the system to adapt to varying service speeds without starvation. The producer can dynamically allocate buffers based on consumer readiness.
2Productivity
If slower virtualized services occupy all descriptors in the ring buffer, then those services can process data, but faster services are starved and cannot access the ring buffer
Solution Approach 1:
The patent segments ring buffer management into separate descriptor enqueuing and data buffer dequeuing operations. Services can enqueue descriptors without immediately occupying data buffers, and consumers can dequeue buffers independently. This segmentation allows multiple services with different speeds to coexist without one service monopolizing the buffer.
Solution Approach 2:
The patent introduces an intermediary mechanism where the producer manages descriptor enrollment and consumer manages buffer consumption. This intermediary layer decouples the direct relationship between descriptor occupation and buffer consumption, allowing faster services to proceed without being blocked by slower services' descriptor processing speed.
3Ease of operation
If traditional ring buffer management is used where consumers return both descriptors and data buffers, then buffer management is simplified, but producers cannot reuse buffers until consumers return them causing blocking
Solution Approach 1:
The patent segments the return operation into separate descriptor return and data buffer return actions. Consumers can return descriptors immediately after processing while data buffers remain in use until the producer is ready to reuse them. This segmentation allows continuous operation without waiting for full buffer return, eliminating the blocking delay.
Solution Approach 2:
The patent implements preliminary buffer allocation where the producer pre-allocates data buffers and enrolls descriptors before the consumer has finished processing. This allows the producer to prepare new buffers in advance, ensuring continuous availability of buffers for new data without waiting for consumer completion. The consumer processes data while the producer prepares the next set of buffers.
Data Source
AI summary
Technologies for managing a single-producer and single-consumer ring include a producer of a compute node that is configured to allocate data buffers, produce work, and indicate that work has been produced. The compute node is configured to insert reference information for each of the allocated data buffers into respective elements of the ring and store the produced work into the data buffers. The compute node includes a consumer configured to request the produced work from the ring. The compute node is further configured to dequeue the reference information from each of the elements of the ring that correspond to the portion of data buffers in which the produced work has been stored, and set each of the elements of the ring for which the reference information has been dequeued to an empty (i.e., NULL) value. Other embodiments are described herein.