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<?xml version="1.0"?> |
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|
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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|
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<refentry id="cpu_percent_usage"> |
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|
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<refentryinfo> |
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<date>$Date: 2003/10/01 14:59:11 $</date> |
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<releaseinfo>$Id: cpu_percent_usage.xml,v 1.1 2003/10/01 14:59:11 tdb Exp $</releaseinfo> |
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</refentryinfo> |
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|
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<refmeta> |
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<refentrytitle>cpu_percent_usage</refentrytitle> |
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<manvolnum>3</manvolnum> |
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<refmiscinfo>i-scream</refmiscinfo> |
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</refmeta> |
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|
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<refnamediv> |
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<refname>cpu_percent_usage</refname> |
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<refname>get_cpu_totals</refname> |
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<refname>get_cpu_diff</refname> |
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<refpurpose>get cpu usage</refpurpose> |
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</refnamediv> |
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|
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<refsynopsisdiv> |
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<funcsynopsis> |
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<funcsynopsisinfo>#include <statgrab.h></funcsynopsisinfo> |
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<funcprototype> |
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<funcdef>cpu_percent_t *<function>cpu_percent_usage</function></funcdef> |
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<void/> |
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</funcprototype> |
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<funcprototype> |
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<funcdef>cpu_states_t *<function>get_cpu_totals</function></funcdef> |
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<void/> |
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</funcprototype> |
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<funcprototype> |
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<funcdef>cpu_states_t *<function>get_cpu_diff</function></funcdef> |
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<void/> |
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</funcprototype> |
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</funcsynopsis> |
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</refsynopsisdiv> |
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|
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<refsect1> |
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<title>Description</title> |
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<para> |
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<function>get_cpu_totals()</function> and |
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<function>get_cpu_diff()</function> both return static pointers |
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of type <structname>cpu_states_t</structname>. |
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<function>get_cpu_totals()</function> returns the total amount of |
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"ticks" the operating system has spent in each of the different |
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states. <function>get_cpu_diff()</function> returns the |
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difference in "ticks" for each of the states since last time |
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<function>get_cpu_diff()</function> or |
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<function>get_cpu_totals()</function> was called. If it has never |
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been called, it will return the result of |
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<function>get_cpu_totals()</function>. |
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</para> |
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<para> |
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The value stored (the "ticks") will vary between operating |
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systems. For example Solaris has a total of 100 per second, |
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while Linux has substantially more. Also, different operating |
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systems store different information - you won't find nice cpu on |
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Solaris for example. |
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</para> |
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<para> |
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Because of this, you will ideally always want to work on a scale |
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against the total, or in percentages. |
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</para> |
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<para> |
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<function>cpu_percent_usage()</function> returns a pointer to a |
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static <structname>cpu_percent_t</structname>. The function |
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calls <function>get_cpu_diff()</function> and changes the values |
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into percentages. If it has never been called before (and nor has |
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<function>get_cpu_totals()</function> or |
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<function>get_cpu_diff()</function>), the returned percentages |
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will be the systems total ever since its uptime. (Unless the |
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counters have cycled) |
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</para> |
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</refsect1> |
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|
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<refsect1> |
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<title>Return Values</title> |
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|
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<para> |
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There are two structures returned by the CPU statistics |
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functions. |
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</para> |
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|
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<programlisting> |
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typedef struct{ |
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long long user; |
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long long kernel; |
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long long idle; |
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long long iowait; |
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long long swap; |
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long long nice; |
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long long total; |
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time_t systime; |
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}cpu_states_t; |
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</programlisting> |
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|
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<programlisting> |
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typedef struct{ |
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float user; |
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float kernel; |
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float idle; |
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float iowait; |
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float swap; |
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float nice; |
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time_t time_taken; |
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}cpu_percent_t; |
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</programlisting> |
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|
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<variablelist> |
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<varlistentry> |
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<term> |
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<structfield>user</structfield> |
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<structfield>kernel</structfield> |
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<structfield>idle</structfield> |
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<structfield>iowait</structfield> |
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<structfield>swap</structfield> |
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<structfield>nice</structfield> |
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</term> |
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<listitem> |
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<para> |
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The different CPU states. |
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</para> |
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</listitem> |
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</varlistentry> |
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<varlistentry> |
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<term> |
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<structfield>systime</structfield> |
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<structfield>time_taken</structfield> |
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</term> |
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<listitem> |
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<para> |
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The time taken in seconds since the last call of the |
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function, or the system time. |
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</para> |
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</listitem> |
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</varlistentry> |
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</variablelist> |
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</refsect1> |
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|
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<refsect1> |
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<title>See Also</title> |
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|
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<simplelist type="inline"> |
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<member> |
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<citerefentry> |
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<refentrytitle>statgrab</refentrytitle> |
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<manvolnum>3</manvolnum> |
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</citerefentry> |
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</member> |
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</simplelist> |
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</refsect1> |
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|
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<refsect1> |
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<title>Website</title> |
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|
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<simplelist type="vert"> |
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<member> |
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<ulink url="http://www.i-scream.org">http://www.i-scream.org</ulink> |
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</member> |
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</simplelist> |
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</refsect1> |
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|
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</refentry> |
