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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>4.2.3. Track Cumulative IO</title><link rel="stylesheet" href="./Common_Content/css/default.css" type="text/css" /><meta name="generator" content="publican 1.6" /><meta name="package" content="Systemtap-SystemTap_Beginners_Guide-1.0-en-US-2.0-2" /><link rel="home" href="index.html" title="SystemTap Beginners Guide" /><link rel="up" href="mainsect-disk.html" title="4.2. Disk" /><link rel="prev" href="iotimesect.html" title="4.2.2. Tracking I/O Time For Each File Read or Write" /><link rel="next" href="traceio2sect.html" title="4.2.4. I/O Monitoring (By Device)" /></head><body class=""><p id="title"><a class="left" href="http://www.fedoraproject.org"><img src="Common_Content/images/image_left.png" alt="Product Site" /></a><a class="right" href="http://docs.fedoraproject.org"><img src="Common_Content/images/image_right.png" alt="Documentation Site" /></a></p><ul class="docnav"><li class="previous"><a accesskey="p" href="iotimesect.html"><strong>Prev</strong></a></li><li class="next"><a accesskey="n" href="traceio2sect.html"><strong>Next</strong></a></li></ul><div xml:lang="en-US" class="section" title="4.2.3. Track Cumulative IO" lang="en-US"><div class="titlepage"><div><div><h3 class="title" id="traceiosect">4.2.3. Track Cumulative IO</h3></div></div></div><a id="id2746317" class="indexterm"></a><a id="id2750819" class="indexterm"></a><a id="id3008975" class="indexterm"></a><a id="id2848628" class="indexterm"></a><a id="id2773546" class="indexterm"></a><a id="id2838194" class="indexterm"></a><div class="para">
This section describes how to track the cumulative amount of I/O to the system.
</div><div class="formalpara"><h5 class="formalpara" id="traceio">traceio.stp</h5>
<pre class="programlisting">
#! /usr/bin/env stap
# traceio.stp
# Copyright (C) 2007 Red Hat, Inc., Eugene Teo <eteo@redhat.com>
# Copyright (C) 2009 Kai Meyer <kai@unixlords.com>
# Fixed a bug that allows this to run longer
# And added the humanreadable function
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
#
global reads, writes, total_io
probe vfs.read.return {
reads[pid(),execname()] += $return
total_io[pid(),execname()] += $return
}
probe vfs.write.return {
writes[pid(),execname()] += $return
total_io[pid(),execname()] += $return
}
function humanreadable(bytes) {
if (bytes > 1024*1024*1024) {
return sprintf("%d GiB", bytes/1024/1024/1024)
} else if (bytes > 1024*1024) {
return sprintf("%d MiB", bytes/1024/1024)
} else if (bytes > 1024) {
return sprintf("%d KiB", bytes/1024)
} else {
return sprintf("%d B", bytes)
}
}
probe timer.s(1) {
foreach([p,e] in total_io- limit 10)
printf("%8d %15s r: %12s w: %12s\n",
p, e, humanreadable(reads[p,e]),
humanreadable(writes[p,e]))
printf("\n")
# Note we don't zero out reads, writes and total_io,
# so the values are cumulative since the script started.
}
</pre>
</div><div class="para">
<a class="xref" href="traceiosect.html#traceio" title="traceio.stp">traceio.stp</a> prints the top ten executables generating I/O traffic over time. In addition, it also tracks the cumulative amount of I/O reads and writes done by those ten executables. This information is tracked and printed out in 1-second intervals, and in descending order.
</div><a id="id2816943" class="indexterm"></a><a id="id3033599" class="indexterm"></a><a id="id3070962" class="indexterm"></a><div class="para">
Note that <a class="xref" href="traceiosect.html#traceio" title="traceio.stp">traceio.stp</a> also uses the local variable <code class="command">$return</code>, which is also used by <a class="xref" href="mainsect-disk.html#scriptdisktop" title="disktop.stp">disktop.stp</a> from <a class="xref" href="mainsect-disk.html#disktop" title="4.2.1. Summarizing Disk Read/Write Traffic">Section 4.2.1, “Summarizing Disk Read/Write Traffic”</a>.
</div><div class="example" id="traceiooutput"><div class="example-contents"><pre class="screen">
[...]
Xorg r: 583401 KiB w: 0 KiB
floaters r: 96 KiB w: 7130 KiB
multiload-apple r: 538 KiB w: 537 KiB
sshd r: 71 KiB w: 72 KiB
pam_timestamp_c r: 138 KiB w: 0 KiB
staprun r: 51 KiB w: 51 KiB
snmpd r: 46 KiB w: 0 KiB
pcscd r: 28 KiB w: 0 KiB
irqbalance r: 27 KiB w: 4 KiB
cupsd r: 4 KiB w: 18 KiB
Xorg r: 588140 KiB w: 0 KiB
floaters r: 97 KiB w: 7143 KiB
multiload-apple r: 543 KiB w: 542 KiB
sshd r: 72 KiB w: 72 KiB
pam_timestamp_c r: 138 KiB w: 0 KiB
staprun r: 51 KiB w: 51 KiB
snmpd r: 46 KiB w: 0 KiB
pcscd r: 28 KiB w: 0 KiB
irqbalance r: 27 KiB w: 4 KiB
cupsd r: 4 KiB w: 18 KiB
</pre></div><h6>Example 4.8. <a class="xref" href="traceiosect.html#traceio" title="traceio.stp">traceio.stp</a> Sample Output</h6></div><br class="example-break" /></div><ul class="docnav"><li class="previous"><a accesskey="p" href="iotimesect.html"><strong>Prev</strong>4.2.2. Tracking I/O Time For Each File Read or Wr...</a></li><li class="up"><a accesskey="u" href="#"><strong>Up</strong></a></li><li class="home"><a accesskey="h" href="index.html"><strong>Home</strong></a></li><li class="next"><a accesskey="n" href="traceio2sect.html"><strong>Next</strong>4.2.4. I/O Monitoring (By Device)</a></li></ul></body></html>
