iosynctest.rb

require "tempfile"

data = "test"
[:flush, :fsync, :fdatasync].each do |method|
  puts "---- #{method} ----"
  res = []
  10.times do
    Tempfile.open("testtmpfile") do |f|
      before = Time.now
      10000.times do |i|
        f.print(data)
        f.send(method)
      end
      res << (Time.now - before)
    end
  end
  puts "#{method}: #{res.inject(0) {|res, t| res + t } / res.length} sec"
end
# ---- flush ----
# flush: 0.06868516690000001 sec
# ---- fsync ----
# fsync: 3.1406286125999996 sec
# ---- fdatasync ----
# fdatasync: 3.1831921884 sec