#! /usr/bin/env stap

global traced_pid, command
global pgout, bgwriteout, kupdate

function log_event:long ()
{
  return (!traced_pid || traced_pid == pid())
}

probe kernel.trace("balance_dirty_pages")		# v3.2+
{
  if (!log_event()) next
  bgwriteout[pid()] <<< (@defined($dirtied) ? $dirtied
			 : (@defined($written) ? $written : $count))
  command[pid()] = execname()
}

probe kernel.trace("writeback_pages_written")	# v2.6.36+
{
  if (!log_event()) next
  kupdate[pid()] <<< (@defined($pages_written) ? $pages_written : $count)
  command[pid()] = execname()
}

probe kernel.trace("mm_vmscan_writepage")		# v2.6.36+
{
  if (!log_event()) next
  pgout[pid()] <<< 1
  command[pid()] = execname()
}

probe begin {
  printf("Starting data collection\n")
  if (target())
    printf("mode Specific Pid, traced pid: %d\n\n", target())
  else
    printf("mode - All Pids\n\n")
}

probe end, error {
  printf("Terminating data collection\n")
  printf("                               Pdflush    Pdflush    Kupdate    Kupdate       Pgout\n")
  printf("Command                 Pid      count        sum      count        sum       count\n")
  printf("-------                 ---    -------    -------    -------    -------       -----\n")
  foreach (pid+ in command)
    printf("%-16s %10d %10d %10d %10d %10d %11d\n",
           command[pid], pid,
           @count(bgwriteout[pid]),
           (@count(bgwriteout[pid]) ? @sum(bgwriteout[pid]) : 0),
           @count(kupdate[pid]),
           (@count(kupdate[pid]) ? @sum(kupdate[pid]) : 0),
           @count(pgout[pid]))
}