Hardware Latency Measurement with Fine-Grained Transaction Filtering
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Solution Overview
Problem
In silicon environments, full latency tracking is impractical due to reduced observability, making it difficult to measure latency effectively in modern digital systems.
Innovation Solution
A self-contained register transfer language (RTL) component encapsulates latency measurement, combined with a filter to selectively measure transaction classes based on conditions, ensuring correct and versatile latency measurement across the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full transaction tracking is implemented for latency measurement, then measurement precision is improved, but device complexity increases and becomes impractical in silicon environments
Solution Approach 1:
The patent segments the transaction tracking system into multiple specialized components: start event detectors for different transaction types, stop event detectors, cycle counters, and filters. Each component handles a specific aspect of latency measurement, making the overall system more manageable and implementable in silicon while maintaining full transaction tracking capability
Solution Approach 2:
The patent introduces intermediary components such as filters that selectively pass specific transaction classes to the measurement logic, and event detectors that mediate between raw transaction signals and the latency measurement mechanism. These intermediaries simplify the core measurement logic while enabling precise measurement of specific transaction types
2Measurement precision
If full transaction tracking is implemented for latency measurement, then measurement precision is improved, but ease of operation deteriorates due to reduced observability in silicon
Solution Approach 1:
The latency measurement system is designed to be self-contained and self-servicing. The start event detectors automatically detect transaction beginnings, cycle counters autonomously track elapsed cycles, and stop event detectors independently identify transaction completions. This self-service architecture reduces the need for external observability and manual intervention, making the system easier to operate in silicon environments
Solution Approach 2:
The patent merges multiple measurement functions into unified components. For example, the cycle counter simultaneously tracks time for multiple transaction types, and the filter combines transaction classification with measurement enablement. This merging reduces the number of separate observability points needed while maintaining measurement precision
3Adaptability or versatility
If selective measurement of transaction classes is implemented, then adaptability is improved, but device complexity increases
Solution Approach 1:
The filter component is designed to be dynamically configurable through sideband data that can be programmed to match different transaction classes. The measurement system can adapt its behavior based on the filtered transaction type, allowing versatile measurement of different transaction classes without requiring completely separate measurement paths for each type
Solution Approach 2:
The patent implements universal measurement components that can handle multiple transaction classes. The cycle counter, stop event detector, and latency calculation logic serve multiple transaction types simultaneously, controlled by the filter configuration. This multi-functionality provides adaptability across different transaction classes without proportionally increasing device complexity
Data Source
AI summary
Methods, systems and apparatuses may provide for technology that includes configuration registers to maintain state information, a filter coupled to the configuration registers, the filter to extract transactions of interest from a plurality of incoming transactions based on the state information, wherein the transactions of interest are extracted on a transaction-by-transaction basis, a first hardware path coupled to the filter, the first hardware path to generate a count of the transactions of interest on a cycle-by-cycle basis, a second hardware path coupled to the filter, the second hardware path to measure a total latency of the transactions of interest on the cycle-by-cycle basis, and an output interface coupled to the first hardware path and the second hardware path, the output interface to determine an average latency of the transactions of interest based on the count of the transactions of interest and the total latency of the transactions of interest.