watch /proc/softirqs and print deltas of each metric at an interval

softirq-watch.rb

#!/usr/bin/ruby

#                     CPU0       CPU1       CPU2       CPU3       CPU4       CPU5       CPU6       CPU7       CPU8       CPU9       CPU10      CPU11      CPU12      CPU13      CPU14
#          HI:          0          0          0          0          0          0          0          0          0          0          0          0          0          0          0
#       TIMER:    2344143    2305156    2295889    2278479    2274008    2260063    2237324    2245718          0          0          0          0          0          0          0
#      NET_TX:   11309569      76523      76961      77020      77086      76261      78908      76016          0          0          0          0          0          0          0
#      NET_RX:   11442620      47843      49607      48089      48989      45698      49201      41453          0          0          0          0          0          0          0
#       BLOCK:          0          0          0          0          0          0          0          0          0          0          0          0          0          0          0
#BLOCK_IOPOLL:          0          0          0          0          0          0          0          0          0          0          0          0          0          0          0
#     TASKLET:     129524       1042       1140       1240       1029       1074       1203       1114          0          0          0          0          0          0          0
#       SCHED:     409281     357909     325891     313242     310618     305667     302294     298887          0          0          0          0          0          0          0
#     HRTIMER:          0          0          0          0          0          0          0          0          0          0          0          0          0          0          0
#         RCU:    1311479    1266743    1259308    1248418    1245865    1240926    1223763    1233068          0          0          0          0          0          0          0

prev = Hash.new(0)

loop do
  File.read('/proc/softirqs').each_line do |l|
    l.chomp!
    if l =~ /:/
      d = l.split
      name = d.delete_at(0)
      total = d.inject(0){|sum,x| sum + x.to_i }

      diff = total - prev[name]
      printf "%-20s: %d\n", name, diff
      prev[name] = total
    end
  end
  printf "\n"
  sleep 3
end