stats/irq_noise

#!/usr/bin/env ruby

RESULT_ROOT = ENV['RESULT_ROOT']

LKP_SRC = ENV['LKP_SRC'] || File.dirname(File.dirname(File.realpath($PROGRAM_NAME)))
require "#{LKP_SRC}/lib/ftrace"
require "#{LKP_SRC}/lib/common"

# Analyze these samples to get how many times irq/softirq happened
# and how long they take
class IrqAnalysis
  def initialize(sample_array)
    @sample_array = sample_array
    @last = nil
    @irq = {}
    @softirq = {}
    @irq_nr = @irq_time = @softirq_nr = @softirq_time = 0
  end

  attr_reader :irq_nr, :irq_time, :softirq_nr, :softirq_time

  def produce_result
    @irq.each do |_, array|
      @irq_nr += array.length
      @irq_time += array.inject(0, :+)
    end
    @softirq.each do |_, array|
      @softirq_nr += array.length
      @softirq_time += array.inject(0, :+)
    end

    puts "irq_nr: #{@irq_nr}"
    puts "softirq_nr: #{@softirq_nr}"
    puts "irq_time: #{@irq_time}us"
    puts "softirq_time: #{@softirq_time}us"
  end

  def mismatch(s1, s2)
    return true if s1.pid != s2.pid

    key = 'irq'
    key = 'vec' if s1.type == :softirq_entry
    return true if s1.data[key] != s2.data[key]
    false
  end

  def process(s1, s2)
    return if mismatch(s1, s2)

    t = (s2.timestamp * 1_000_000).to_i - (s1.timestamp * 1_000_000).to_i
    if s1.type == :softirq_entry
      vec_nr = s1.data['vec']
      @softirq[vec_nr] ||= []
      @softirq[vec_nr] << t
    else
      irq_nr = s1.data['irq']
      @irq[irq_nr] ||= []
      @irq[irq_nr] << t
    end
  end

  def analyze
    @sample_array.each do |sample|
      if @last
        if sample.type == :softirq_exit || sample.type == :irq_handler_exit
          process @last, sample
        end
        @last = nil
      elsif sample.type == :softirq_entry || sample.type == :irq_handler_entry
        @last = sample
      end
    end
    produce_result
  end
end

def extract_ftrace
  fn = "#{RESULT_ROOT}/ftrace.data.xz"
  fmts_dir = "#{RESULT_ROOT}/ftrace_events"
  file = zopen(fn)
  trace = TPTrace.new file, fmts_dir

  samples = {}
  # interrupt handler will not be migrated so to simply entry/exit
  # pair match, sort these samples according to CPU number
  trace.each do |sample|
      samples[sample.cpu] ||= []
      samples[sample.cpu] << sample
  end

  samples_array = []
  # then we put these sorted lines into a global array
  samples.each do |_, array|
    array.each do |sample|
      samples_array << sample
    end
  end
  samples_array
end

irq_analysis = IrqAnalysis.new extract_ftrace
irq_analysis.analyze