Latency Detection Using Dual Clocks to Prevent SLA Violations
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Solution Overview
Problem
Conventional systems for determining latency in computer systems, such as switches, are inadequate as they rely on simple counting mechanisms that lead to inaccurate latency estimation due to wrapping around of clocks, potentially allowing excessive latency to go undetected, which can violate service level agreements (SLAs).
Innovation Solution
Implementing a system that uses two or more clocks, where one clock counts at a constant rate and the other is modified by a random element after reaching its maximum value, allowing for accurate determination of latency by calculating the time between task enqueuing and dequeuing across both clocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single clock counts time in cycles from zero to maximum before resetting, then the system is simple to implement, but the latency measurement becomes inaccurate when the clock wraps around
Solution Approach 1:
The patent divides the timing measurement function into multiple independent clocks, each responsible for measuring specific time intervals. This segmentation allows the system to overcome the wrapping limitation of a single clock by using multiple clocks to cover different time ranges, thereby improving measurement accuracy without requiring a single complex clock system.
Solution Approach 2:
The patent introduces a new dimension to time measurement by using multiple clocks operating simultaneously. Instead of relying on a single clock's linear counting, the system uses multiple clocks to create a multi-dimensional time measurement space, allowing accurate measurement of latency even when individual clocks wrap around.
2Productivity
If a clock reaches maximum value and wraps around to zero, then the counting mechanism continues without interruption, but the estimated latency becomes significantly underestimated
Solution Approach 1:
The patent implements feedback mechanisms where the system monitors clock values and detects when a clock has wrapped around. Based on this feedback, the system adjusts the latency calculation to account for the wrapping, ensuring accurate measurement while maintaining continuous operation. The feedback loop allows the system to correct measurement errors caused by clock wrapping.
Solution Approach 2:
The patent replaces the mechanical single-clock counting system with a multi-clock system that uses different counting mechanisms. By substituting the single-clock approach with multiple clocks, the system eliminates the wrapping problem while maintaining continuous counting capability, as each clock can be independently managed and synchronized.
3Device complexity
If conventional single-clock systems are used, then the system remains simple and efficient, but excessive latency may go undetected due to wrapping blind spots
Solution Approach 1:
The patent segments the timing detection function across multiple clocks, each monitoring specific time intervals. This segmentation eliminates blind spots where latency could go undetected, as multiple clocks provide overlapping coverage that ensures all latency values, including those exceeding the maximum clock count, are reliably detected.
Solution Approach 2:
The patent adds another dimension to latency detection by using multiple clocks simultaneously. This multi-dimensional approach creates a comprehensive monitoring framework that detects excessive latency reliably, as the system can identify when a task exceeds the maximum clock count by observing the relationships between multiple clock values.
4Measurement precision
If multiple clocks are used to measure latency accurately, then latency detection precision improves, but the system complexity increases
Solution Approach 1:
The patent designs multiple clocks to serve universal purposes in latency measurement. Each clock is engineered to perform the same basic function of timing measurement, but collectively they provide enhanced accuracy. The clocks are synchronized and coordinated to work together as a unified system, achieving multi-functionality that improves measurement precision without proportionally increasing complexity.
Data Source
AI summary
A device, a switch, and a method of determining latency which exceeds a threshold are described. A task is enqueued and a time is determined based on two clocks. A time the task is dequeued is determined based on the two clocks. Based on the time of enqueue and the time of dequeue according to each of the two clocks, the task is identified as meeting or violating a service level agreement.