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1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 1<?xml version="1.0" encoding="UTF-8" standalone="no"?>
2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title xmlns:d="http://docbook.org/ns/docbook">5.3.4. Monitoring Polling Applications</title><link rel="stylesheet" type="text/css" href="Common_Content/css/default.css" /><link rel="stylesheet" media="print" href="Common_Content/css/print.css" type="text/css" /><meta xmlns:d="http://docbook.org/ns/docbook" name="generator" content="not publican" /><meta xmlns:d="http://docbook.org/ns/docbook" name="package" content="" /><link rel="home" href="index.html" title="SystemTap Beginners Guide" /><link rel="up" href="mainsect-profiling.html" title="5.3. Profiling" /><link rel="prev" href="threadtimessect.html" title="5.3.3. Determining Time Spent in Kernel and User Space" /><link rel="next" href="topsyssect.html" title="5.3.5. Tracking Most Frequently Used System Calls" /></head><body><p id="title"></p><ul class="docnav top"><li class="previous"><a accesskey="p" href="threadtimessect.html"><strong>Prev</strong></a></li><li class="home">SystemTap Beginners Guide</li><li class="next"><a accesskey="n" href="topsyssect.html"><strong>Next</strong></a></li></ul><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="timeoutssect"> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title xmlns:d="http://docbook.org/ns/docbook">5.3.4. Monitoring Polling Applications</title><link rel="stylesheet" type="text/css" href="Common_Content/css/default.css" /><link rel="stylesheet" media="print" href="Common_Content/css/print.css" type="text/css" /><meta xmlns:d="http://docbook.org/ns/docbook" name="generator" content="not publican" /><meta xmlns:d="http://docbook.org/ns/docbook" name="package" content="" /><link rel="home" href="index.html" title="SystemTap Beginners Guide" /><link rel="up" href="mainsect-profiling.html" title="5.3. Profiling" /><link rel="prev" href="threadtimessect.html" title="5.3.3. Determining Time Spent in Kernel and User Space" /><link rel="next" href="topsyssect.html" title="5.3.5. Tracking Most Frequently Used System Calls" /></head><body><p id="title"></p><ul class="docnav top"><li class="previous"><a accesskey="p" href="threadtimessect.html"><strong>Prev</strong></a></li><li class="home">SystemTap Beginners Guide</li><li class="next"><a accesskey="n" href="topsyssect.html"><strong>Next</strong></a></li></ul><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="timeoutssect">
3 ⁠</a>5.3.4. Monitoring Polling Applications</h3></div></div></div><a id="idm47006125928784" class="indexterm"></a><a id="idm47006120521200" class="indexterm"></a><a id="idm47006119729264" class="indexterm"></a><a id="idm47006121542656" class="indexterm"></a><div class="para"> 3 ⁠</a>5.3.4. Monitoring Polling Applications</h3></div></div></div><a id="idp71890970445760" class="indexterm"></a><a id="idp71890961144160" class="indexterm"></a><a id="idp71890973637392" class="indexterm"></a><a id="idp71890960995472" class="indexterm"></a><div class="para">
4 This section describes how to identify and monitor which applications are polling. Doing so allows you to track 4 This section describes how to identify and monitor which applications are polling. Doing so allows you to track
5 unnecessary or excessive polling, which can help you pinpoint areas for improvement in terms of CPU usage 5 unnecessary or excessive polling, which can help you pinpoint areas for improvement in terms of CPU usage
6 and power savings. 6 and power savings.
7 </div><div class="para"><div xmlns:d="http://docbook.org/ns/docbook" class="title">timeout.stp</div> 7 </div><div class="para"><div xmlns:d="http://docbook.org/ns/docbook" class="title">timeout.stp</div>
8<pre class="programlisting">#! /usr/bin/env stap 8<pre class="programlisting">#! /usr/bin/env stap
9# Copyright (C) 2009 Red Hat, Inc. 9# Copyright (C) 2009-2018 Red Hat, Inc.
10# Written by Ulrich Drepper &lt;drepper@redhat.com&gt; 10# Written by Ulrich Drepper &lt;drepper@redhat.com&gt;
11# Modified by William Cohen &lt;wcohen@redhat.com&gt; 11# Modified by William Cohen &lt;wcohen@redhat.com&gt;
12 12
@@ -14,12 +14,12 @@ global process, timeout_count, to
14global poll_timeout, epoll_timeout, select_timeout, itimer_timeout 14global poll_timeout, epoll_timeout, select_timeout, itimer_timeout
15global nanosleep_timeout, futex_timeout, signal_timeout 15global nanosleep_timeout, futex_timeout, signal_timeout
16 16
17probe syscall.poll, syscall.epoll_wait { 17probe syscall.{poll,epoll_wait} {
18 if (timeout) to[pid()]=timeout 18 if (timeout) to[pid()]=timeout
19} 19}
20 20
21probe syscall.poll.return { 21probe syscall.poll.return {
22 if ($return == 0 &amp;&amp; to[pid()] &gt; 0 ) { 22 if (retval == 0 &amp;&amp; to[pid()] &gt; 0 ) {
23 poll_timeout[pid()]++ 23 poll_timeout[pid()]++
24 timeout_count[pid()]++ 24 timeout_count[pid()]++
25 process[pid()] = execname() 25 process[pid()] = execname()
@@ -28,16 +28,16 @@ probe syscall.poll.return {
28} 28}
29 29
30probe syscall.epoll_wait.return { 30probe syscall.epoll_wait.return {
31 if ($return == 0 &amp;&amp; to[pid()] &gt; 0 ) { 31 if (retval == 0 &amp;&amp; to[pid()] &gt; 0 ) {
32 epoll_timeout[pid()]++ 32 epoll_timeout[pid()]++
33 timeout_count[pid()]++ 33 timeout_count[pid()]++
34 process[p] = execname() 34 process[pid()] = execname()
35 delete to[pid()] 35 delete to[pid()]
36 } 36 }
37} 37}
38 38
39probe syscall.select.return { 39probe syscall.select.return {
40 if ($return == 0) { 40 if (retval == 0) {
41 select_timeout[pid()]++ 41 select_timeout[pid()]++
42 timeout_count[pid()]++ 42 timeout_count[pid()]++
43 process[pid()] = execname() 43 process[pid()] = execname()
@@ -45,7 +45,7 @@ probe syscall.select.return {
45} 45}
46 46
47probe syscall.futex.return { 47probe syscall.futex.return {
48 if (errno_str($return) == "ETIMEDOUT") { 48 if (errno_str(retval) == "ETIMEDOUT") {
49 futex_timeout[pid()]++ 49 futex_timeout[pid()]++
50 timeout_count[pid()]++ 50 timeout_count[pid()]++
51 process[pid()] = execname() 51 process[pid()] = execname()
@@ -53,7 +53,7 @@ probe syscall.futex.return {
53} 53}
54 54
55probe syscall.nanosleep.return { 55probe syscall.nanosleep.return {
56 if ($return == 0) { 56 if (retval == 0) {
57 nanosleep_timeout[pid()]++ 57 nanosleep_timeout[pid()]++
58 timeout_count[pid()]++ 58 timeout_count[pid()]++
59 process[pid()] = execname() 59 process[pid()] = execname()
@@ -67,7 +67,7 @@ probe kernel.function("it_real_fn") {
67} 67}
68 68
69probe syscall.rt_sigtimedwait.return { 69probe syscall.rt_sigtimedwait.return {
70 if (errno_str($return) == "EAGAIN") { 70 if (errno_str(retval) == "EAGAIN") {
71 signal_timeout[pid()]++ 71 signal_timeout[pid()]++
72 timeout_count[pid()]++ 72 timeout_count[pid()]++
73 process[pid()] = execname() 73 process[pid()] = execname()
@@ -99,13 +99,30 @@ probe timer.s(1) {
99 signal_timeout[p], process[p]) 99 signal_timeout[p], process[p])
100 } 100 }
101} 101}
102
103global prom_arr
104
105probe prometheus {
106 foreach (p in timeout_count- limit 20) {
107 prom_arr[poll_timeout[p], select_timeout[p],
108 epoll_timeout[p], itimer_timeout[p],
109 futex_timeout[p], nanosleep_timeout[p],
110 signal_timeout[p]] = process[p]
111 }
112
113 @prometheus_dump_array7(prom_arr, "process", "poll_timeout", "select_timeout",
114 "epoll_timeout", "itimer_timeout",
115 "futex_timeout", "nanosleep_timeout",
116 "signal_timeout")
117 delete prom_arr
118}
102</pre> 119</pre>
103</div><div class="para"> 120</div><div class="para">
104 <a class="xref" href="timeoutssect.html#timeouts">timeout.stp</a> tracks how many times each 121 <a class="xref" href="timeoutssect.html#timeouts">timeout.stp</a> tracks how many times each
105 of the following system calls completed 122 of the following system calls completed
106 due to time expiring rather than due to an actual event 123 due to time expiring rather than due to an actual event
107 occurring: 124 occurring:
108 </div><div xmlns:d="http://docbook.org/ns/docbook" class="itemizedlist"><ul><li class="listitem"><div class="para"><code class="command">poll</code></div></li><li class="listitem"><div class="para"><code class="command">select</code></div></li><li class="listitem"><div class="para"><code class="command">epoll</code></div></li><li class="listitem"><div class="para"><code class="command">itimer</code></div></li><li class="listitem"><div class="para"><code class="command">futex</code></div></li><li class="listitem"><div class="para"><code class="command">nanosleep</code></div></li><li class="listitem"><div class="para"><code class="command">signal</code></div></li></ul></div><a id="idm47006129265504" class="indexterm"></a><a id="idm47006120640176" class="indexterm"></a><a id="idm47006125169120" class="indexterm"></a><div class="example"><a id="timeoutsoutput"> 125 </div><div xmlns:d="http://docbook.org/ns/docbook" class="itemizedlist"><ul><li class="listitem"><div class="para"><code class="command">poll</code></div></li><li class="listitem"><div class="para"><code class="command">select</code></div></li><li class="listitem"><div class="para"><code class="command">epoll</code></div></li><li class="listitem"><div class="para"><code class="command">itimer</code></div></li><li class="listitem"><div class="para"><code class="command">futex</code></div></li><li class="listitem"><div class="para"><code class="command">nanosleep</code></div></li><li class="listitem"><div class="para"><code class="command">signal</code></div></li></ul></div><a id="idp71890972012320" class="indexterm"></a><a id="idp71890960012016" class="indexterm"></a><a id="idp71890965642672" class="indexterm"></a><div class="example"><a id="timeoutsoutput">
109 ⁠</a><p class="title"><strong>Example 5.16. <a class="xref" href="timeoutssect.html#timeouts">timeout.stp</a> Sample Output</strong></p><div class="example-contents"><pre class="screen"> uid | poll select epoll itimer futex nanosle signal| process 126 ⁠</a><p class="title"><strong>Example 5.16. <a class="xref" href="timeoutssect.html#timeouts">timeout.stp</a> Sample Output</strong></p><div class="example-contents"><pre class="screen"> uid | poll select epoll itimer futex nanosle signal| process
11028937 | 148793 0 0 4727 37288 0 0| firefox 12728937 | 148793 0 0 4727 37288 0 0| firefox
11122945 | 0 56949 0 1 0 0 0| scim-bridge 12822945 | 0 56949 0 1 0 0 0| scim-bridge
generated by cgit (git 2.34.1) at 2025-11-03 04:01:43 +0000