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Filename : wait4time.stp
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#!/usr/bin/stap

/*
 * Copyright (C) 2006-2007 Red Hat Inc.
 * 
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License v.2.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Print out the time spent in wait4 systemcall
 *
 * Format is:
 * timestamp pid (executabable) wait4: time_us pid
 *
 * 155789807 4196 (ssh) wait4: 12 4197
 * 158270531 3215 (bash) wait4: 5410460 -1
 * 158270659 3215 (bash) wait4: 9 -1
 * 158557461 2614 (sendmail) wait4: 27 -1
 * 158557487 2614 (sendmail) wait4: 5 -1
 *
 */

global start
global wait4_pid

function timestamp:long() {
  return gettimeofday_us() - start
}

function proc:string() {
  return sprintf("%d (%s)", pid(), execname())
}

probe begin {
 start = gettimeofday_us()
}

probe syscall.wait4 {
  // It would be nice to use @entry here, but "pid" has a non-trivial
  // expression in the tapset which we probably shouldn't duplicate.
  wait4_pid[tid()]=pid
}

probe syscall.wait4.return {
  elapsed_time = gettimeofday_us() - @entry(gettimeofday_us())
  printf("%d %s wait4: %d %d\n",  timestamp(), proc(), elapsed_time,
         wait4_pid[tid()])
  delete wait4_pid[tid()]
}