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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 | <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!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. Profiling</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="useful-systemtap-scripts.html" title="Chapter 5. Useful SystemTap Scripts" /><link rel="prev" href="ioblktimesect.html" title="5.2.7. Periodically Print I/O Block Time" /><link rel="next" href="paracallgraph.html" title="5.3.2. Call Graph Tracing" /></head><body><p id="title"></p><ul class="docnav top"><li class="previous"><a accesskey="p" href="ioblktimesect.html"><strong>Prev</strong></a></li><li class="home">SystemTap Beginners Guide</li><li class="next"><a accesskey="n" href="paracallgraph.html"><strong>Next</strong></a></li></ul><div class="section"><div class="titlepage"><div><div><h2 class="title"><a id="mainsect-profiling"> </a>5.3. Profiling</h2></div></div></div><div class="para">The following sections showcase scripts that profile kernel activity by monitoring function calls.</div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="countcallssect"> </a>5.3.1. Counting Function Calls Made</h3></div></div></div><a id="id5076" class="indexterm"></a><a id="id5079" class="indexterm"></a><a id="id5082" class="indexterm"></a><a id="id5085" class="indexterm"></a><a id="id5088" class="indexterm"></a><div class="para">This section describes how to identify how many times the system called a specific kernel function in a 30-second sample. Depending on the use of wildcards, you can also use this script to target multiple kernel functions.</div><div class="para"><div xmlns:d="http://docbook.org/ns/docbook" class="title">functioncallcount.stp</div> <pre class="programlisting">#! /usr/bin/env stap # The following line command will probe all the functions # in kernel's memory management code: # # stap functioncallcount.stp "*@mm/*.c" probe kernel.function(@1).call { # probe functions listed on commandline called[ppfunc()] <<< 1 # add a count efficiently } global called probe end { foreach (fn in called-) # Sort by call count (in decreasing order) # (fn+ in called) # Sort by function name printf("%s %d\n", fn, @count(called[fn])) exit() } </pre> </div><div class="para"><a class="xref" href="mainsect-profiling.html#countcalls">functioncallcount.stp</a> takes the targeted kernel function as an argument. The argument supports wildcards, which enables you to target multiple kernel functions up to a certain extent.</div><a id="id5100" class="indexterm"></a><a id="id5103" class="indexterm"></a><a id="id5106" class="indexterm"></a><div class="para">The output of <a class="xref" href="mainsect-profiling.html#countcalls">functioncallcount.stp</a> contains the name of the function called and how many times it was called during the sample time (in alphabetical order). <a class="xref" href="mainsect-profiling.html#countcallsoutput">Example 5.13, “functioncallcount.stp Sample Output”</a> contains an excerpt from the output of <code class="command">stap functioncallcount.stp "*@mm/*.c"</code>:</div><div class="example"><a id="countcallsoutput"> </a><p class="title"><strong>Example 5.13. <a class="xref" href="mainsect-profiling.html#countcalls">functioncallcount.stp</a> Sample Output</strong></p><div class="example-contents"><pre class="screen">[...] __vma_link 97 __vma_link_file 66 __vma_link_list 97 __vma_link_rb 97 __xchg 103 add_page_to_active_list 102 add_page_to_inactive_list 19 add_to_page_cache 19 add_to_page_cache_lru 7 all_vm_events 6 alloc_pages_node 4630 alloc_slabmgmt 67 anon_vma_alloc 62 anon_vma_free 62 anon_vma_lock 66 anon_vma_prepare 98 anon_vma_unlink 97 anon_vma_unlock 66 arch_get_unmapped_area_topdown 94 arch_get_unmapped_exec_area 3 arch_unmap_area_topdown 97 atomic_add 2 atomic_add_negative 97 atomic_dec_and_test 5153 atomic_inc 470 atomic_inc_and_test 1 [...]</pre></div></div></div></div><ul class="docnav"><li class="previous"><a accesskey="p" href="ioblktimesect.html"><strong>Prev</strong>5.2.7. Periodically Print I/O Block Time</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="paracallgraph.html"><strong>Next</strong>5.3.2. Call Graph Tracing</a></li></ul></body></html>
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