Stateless Data Linear Address Capture for PEBS
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In modern processors, precise event-based sampling (PEBS) for collecting runtime information can consume significant processor resources, especially when dealing with out-of-order execution and memory referencing instructions, leading to performance overhead and increased power consumption.
Innovation Solution
Implementing a stateless capture mechanism for data linear addresses (DLA) during PEBS, which uses a register to store the DLA only when the counter overflows, reducing power consumption and resource usage by minimizing continuous buffer storage and enabling power-saving during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous buffer storage is used for DLA during PEBS, then complete runtime information is captured, but power consumption and resource usage increase
Solution Approach 1:
The patent implements periodic action by using a counter that increments with each instruction and triggers buffer storage only when it overflows, rather than continuously storing. This converts continuous buffer storage into periodic storage events, capturing runtime information at intervals determined by the counter overflow, thereby reducing power consumption while maintaining measurement capability
Solution Approach 2:
The patent extracts only the essential DLA information into a separate buffer when needed, rather than maintaining continuous storage of all runtime information. By extracting and storing only the counter value and associated DLA at overflow points, the system reduces overall resource usage while preserving critical measurement data
2Measurement precision
If PEBS collects state information for out-of-order execution, then debugging accuracy improves, but processor resources are consumed
Solution Approach 1:
The patent segments the PEBS functionality by separating the counter mechanism from the main processor execution path. The counter operates independently and only interacts with the buffer when overflow occurs, isolating the measurement overhead from critical processor resources and minimizing impact on out-of-order execution performance
Solution Approach 2:
The patent uses a simple incrementing counter as a disposable, low-cost mechanism to track instruction progress. Rather than implementing complex continuous monitoring, the system uses a basic counter that is reset after overflow, providing necessary measurement capability with minimal resource investment
3Reliability
If continuous monitoring is performed for PEBS, then event detection accuracy is maintained, but overhead increases
Solution Approach 1:
The patent implements periodic action by using a counter that increments with each instruction and triggers buffer storage only when it overflows, rather than continuously storing. This converts continuous buffer storage into periodic storage events, capturing runtime information at intervals determined by the counter overflow, thereby reducing power consumption while maintaining measurement capability
Solution Approach 2:
The patent applies skipping by bypassing continuous storage operations and only performing buffer writes at counter overflow points. This allows the system to rush through intermediate states without storage overhead, maintaining event detection accuracy at critical points while skipping unnecessary intermediate storage operations
Data Source
AI summary
A processor includes a logic for stateless capture of data linear addresses (DLA) during precise event based sampling (PEBS) for an out-of-order execution engine. The engine may include a PEBS unit with logic to increment a counter each time an instance of a designated micro-op is retired a reorder buffer, capture output DLA referenced by an instance of the micro-op that executes after the counter overflows, set a captured bit associated with a reorder buffer identifier for the instance of the micro-op, and store a PEBS record in a debug storage when the instance of the micro-op is retired from the reorder buffer. The designated micro-op references a DLA of a memory accessible to the processor.