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Custom KProbe Monitoring Tool

·Linux Kernel, Systems, C, Performance·Source Code

Overview

A custom kernel monitoring tool built using Linux kprobes to gain deep insights into kernel behavior, scheduler decisions, and system performance characteristics.

KProbe Monitoring Architecture
KProbe Monitoring Architecture

Features

Context Switch Monitoring

  • Tracks all context switches in real-time
  • Measures time spent in each process
  • Identifies processes causing excessive switching
  • Histogram generation for switch frequency analysis

Interrupt Call Tracking

  • Monitors hardware and software interrupts
  • Measures interrupt handling latency
  • Identifies interrupt storms and bottlenecks
  • Per-CPU interrupt distribution analysis

Job Scheduler Simulation

  • Simulates CFS (Completely Fair Scheduler) behavior
  • Virtual runtime tracking for processes
  • Red-black tree visualization of runqueue
  • What-if analysis for scheduling decisions

Implementation Details

KProbe Architecture

static struct kprobe kp = {
    .symbol_name = "finish_task_switch",
    .pre_handler = handler_pre,
    .post_handler = handler_post,
};

Data Collection

  • Ring buffer for low-overhead event storage
  • Per-CPU buffers to avoid contention
  • Efficient binary format for trace data
  • User-space tools for analysis and visualization

Virtual Runtime Tracking

  • Maintains shadow scheduler state
  • Calculates expected virtual runtime
  • Compares with actual kernel decisions
  • Identifies scheduling anomalies

Use Cases

  1. Performance Debugging: Identify scheduling bottlenecks
  2. Latency Analysis: Measure and reduce system latency
  3. Workload Characterization: Understand application behavior
  4. Educational: Learn kernel internals hands-on

Technical Stack

  • Kernel Module: C with kprobe API
  • User Tools: Python for analysis
  • Visualization: Custom plotting tools
  • Tested on: Linux 5.x kernels