Call Stack Sampling for Idle State Analysis
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Solution Overview
Problem
Current methods for obtaining call stack information in multi-processor systems are inefficient, as they periodically wake up all threads to determine status, which can lead to inaccurate processor usage data and system slowdowns, especially when processor resources are underutilized.
Innovation Solution
A computer-implemented method that monitors processor usage and collects call stack information from identified threads using an underutilized processor, allowing for targeted sampling and profiling to determine idle states and bottlenecks without disrupting active processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all threads are periodically woken to obtain call stack information, then complete thread status data is collected, but system performance decreases and processor resources are wasted
Solution Approach 1:
The patent applies partial action by collecting call stack information from only a subset of threads rather than all threads. The sampling mechanism selects specific threads based on criteria such as thread state or processor activity, obtaining sufficient information for performance analysis without the overhead of examining every thread, thus balancing measurement completeness with system performance.
Solution Approach 2:
The patent implements periodic sampling of call stack information at predetermined time intervals or based on event triggers rather than continuously or on every thread state change. This periodic approach reduces the frequency of intrusive measurements, allowing the system to maintain normal performance while still gathering adequate data for performance analysis.
2Loss of information
If thread status is determined by waking all threads, then complete information is obtained, but processor resources are underutilized and system slows down
Solution Approach 1:
The patent obtains sufficient thread status information by examining only a sampled subset of threads rather than all threads. The sampling strategy is designed to capture representative performance data without requiring the time-consuming operation of waking and examining every thread, thus reducing information loss while minimizing time loss.
Solution Approach 2:
The patent allows the system to self-determine which threads are worth sampling based on predefined criteria such as thread activity state, processor utilization, or performance relevance. This self-service approach automatically identifies the most informative threads for sampling, obtaining necessary status information without manual intervention or exhaustive examination of all threads.
3Measurement precision
If call stack information is collected from all threads, then comprehensive profiling data is obtained, but processor utilization decreases
Solution Approach 1:
The patent collects call stack information from a sampled subset of threads rather than all threads, obtaining sufficient profiling data to identify performance bottlenecks and patterns. This partial sampling approach maintains measurement precision for performance analysis purposes while significantly reducing the processor cycles consumed by the collection process itself.
Solution Approach 2:
The patent changes the sampling parameters dynamically based on system conditions, such as adjusting the sampling rate or selection criteria based on current processor utilization, workload characteristics, or performance thresholds. This allows the system to maintain adequate profiling accuracy while adapting processor resource consumption to current system demands.
Data Source
AI summary
A computer implemented method, apparatus, and computer usable program code for sampling call stack information. Monitoring for an event is performed during an execution of a plurality of threads by a set of processors. A portion of the plurality of threads is identified based on a policy to form a set of identified threads in response to an occurrence of the event. Call stack information is collected for the set of identified threads using an under utilized processor in a set of processors in response to identifying the portion of the plurality of threads, wherein the call stack information is used to profile a processor in the set of processors.