Interrupt Counter Threshold for RDMA Write Immediate
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Solution Overview
Problem
Computer communication systems face inefficiencies in interrupt handling, particularly with remote direct memory access (RDMA) writes, where frequent interrupts can overwhelm receiving entities, leading to unnecessary processing and resource burden.
Innovation Solution
A method and system that utilize a receiving communication adapter to increment an interrupt counter value for RDMA writes with immediate, triggering an interrupt only when the counter exceeds a threshold, thereby limiting the number of interrupts and optimizing processing by the receiving entity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interrupt is sent for every RDMA write with immediate, then the receiving entity is notified of every message, but the receiving entity is overwhelmed by frequent interrupts and experiences unnecessary processing burden
Solution Approach 1:
Multiple individual interrupt signals for each RDMA write with immediate are merged into a single interrupt signal when the interrupt counter exceeds the threshold. This combining approach maintains reliable notification of multiple messages while preventing the receiving entity from being overwhelmed by frequent interrupts, thus resolving the contradiction between notification reliability and processing efficiency.
Solution Approach 2:
The system changes the parameter of interrupt frequency from one interrupt per message to one interrupt per threshold exceeded. By modifying this parameter through the interrupt counter mechanism, the system maintains essential notification functionality while significantly reducing the frequency of interrupts to improve receiving entity processing efficiency.
2Productivity
If the interrupt counter threshold is set low, then interrupts are triggered frequently to ensure processing, but the number of interrupts increases causing system overhead
Solution Approach 1:
The system dynamically adjusts the interrupt triggering parameter based on the configured threshold value. By changing the threshold parameter, the system can balance between processing timeliness and interrupt handling overhead, resolving the contradiction between these two aspects.
Solution Approach 2:
The interrupt counter provides feedback on the number of RDMA writes with immediate received since the last interrupt. This feedback mechanism enables the system to make informed decisions about when to trigger interrupts, balancing processing timeliness with minimizing interrupt overhead through configurable threshold-based feedback control.
3Device complexity
If the interrupt counter threshold is set high, then fewer interrupts are sent reducing overhead, but message processing may be delayed
Solution Approach 1:
The system allows adjustment of the threshold parameter to optimize the balance between interrupt frequency and processing delay. By changing this parameter, administrators can reduce interrupt overhead when acceptable to experience some processing delay, or increase interrupt frequency to minimize delay, thus resolving the contradiction between overhead and time loss.
Data Source
AI summary
A method for issuing interrupts includes a receiving communication adapter receiving a first remote directed memory access (RDMA) write with immediate, identifying a completion queue descriptor corresponding to the first RDMA write with immediate and to a receiving entity, incrementing an interrupt counter in response to the first RDMA write with immediate. The method includes storing, by the receiving communication adapter, in response to determining that the interrupt counter value is less than the interrupt threshold value, data in the first RDMA write with immediate on the receiving device without triggering an interrupt to the receiving entity. The receiving communication adapter receives a second RDMA write with immediate, and increments the interrupt counter value corresponding to the completion queue descriptor in response to the second RDMA write with immediate. The method includes triggering the interrupt to the receiving entity in response to the interrupt counter value exceeding the interrupt threshold.