Hardware Snapshotting for Processor Performance Monitoring

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Solution Overview

Problem

Existing performance monitoring methods in processors incur software overhead and inaccuracies due to the need for software instructions to read performance counters, often disrupting the execution and providing incomplete or inaccurate data.

Innovation Solution

Implementing hardware-based performance monitoring that captures and stores performance counter data independently of software execution, allowing for selective control by virtual machine monitors or hypervisors, and enabling efficient, accurate, and less intrusive data collection from multiple counters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If software instructions are used to read performance counters, then performance monitoring can be implemented, but software overhead increases and execution is disrupted

Engineering Contradiction:

Improveperformance monitoring capabilityVSAvoidsoftware overhead

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the software-based mechanism for reading performance counters with a hardware-based mechanism. The performance monitoring unit is implemented in hardware, allowing counters to be sampled automatically without software intervention. This substitution eliminates the need for software instructions to read counters, thereby removing the associated overhead and execution disruptions while maintaining reliable performance monitoring capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of information

If software instructions are used to read performance counters, then performance data can be collected, but data accuracy deteriorates due to execution disruption

Engineering Contradiction:

Improveperformance data completenessVSAvoidperformance measurement accuracy

Core Design Contradiction:

Loss of informationVSMeasurement precision

Solution Approach 1:

The hardware implementation of the performance monitoring unit enables continuous, uninterrupted sampling of performance counters. Since the monitoring occurs in hardware without requiring software execution, the counters are not disrupted or reset during sampling. This ensures that the performance data collected accurately reflects the actual system state without the measurement errors introduced by software-based reading methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If hardware-based performance monitoring is implemented, then software overhead is reduced, but device complexity increases

Engineering Contradiction:

Improveperformance monitoring efficiencyVSAvoidhardware complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent integrates the performance monitoring unit directly into the processor's existing hardware structure, merging it with the execution core and cache hierarchy. By combining the monitoring functionality with the existing processor components rather than adding separate external hardware, the implementation achieves efficient hardware-based monitoring while minimizing the increase in overall device complexity. The monitoring unit shares resources and interfaces with existing processor elements.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20240330146A1Snapshotting of performance monitoring

Publication Date: 2024.10.03 INTEL CORP

AI summary

Techniques for snapshotting of performance monitoring are described. In an embodiment, an apparatus includes a plurality of performance monitoring hardware resources, hardware to capture a record of state data related to state of the apparatus in connection with an occurrence of an event, and storage to store a first indicator corresponding to at least a first performance monitoring hardware resource of the plurality of performance monitoring hardware resources and to enable the hardware to include, in the record, performance data from the first performance monitoring hardware resource.