| 1 |
<?xml version="1.0"?> |
| 2 |
|
| 3 |
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
| 4 |
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
| 5 |
|
| 6 |
<refentry id="get_memory_stats"> |
| 7 |
|
| 8 |
<refentryinfo> |
| 9 |
<date>$Date: 2004/03/11 17:35:24 $</date> |
| 10 |
<releaseinfo>$Id: get_memory_stats.xml,v 1.3 2004/03/11 17:35:24 tdb Exp $</releaseinfo> |
| 11 |
</refentryinfo> |
| 12 |
|
| 13 |
<refmeta> |
| 14 |
<refentrytitle>get_memory_stats</refentrytitle> |
| 15 |
<manvolnum>3</manvolnum> |
| 16 |
<refmiscinfo>i-scream</refmiscinfo> |
| 17 |
</refmeta> |
| 18 |
|
| 19 |
<refnamediv> |
| 20 |
<refname>get_memory_stats</refname> |
| 21 |
<refname>get_swap_stats</refname> |
| 22 |
<refpurpose>get VM statistics</refpurpose> |
| 23 |
</refnamediv> |
| 24 |
|
| 25 |
<refsynopsisdiv> |
| 26 |
<funcsynopsis> |
| 27 |
<funcsynopsisinfo>#include <statgrab.h></funcsynopsisinfo> |
| 28 |
<funcprototype> |
| 29 |
<funcdef>mem_stat_t *<function>get_memory_stats</function></funcdef> |
| 30 |
<void/> |
| 31 |
</funcprototype> |
| 32 |
<funcprototype> |
| 33 |
<funcdef>swap_stat_t *<function>get_swap_stats</function></funcdef> |
| 34 |
<void/> |
| 35 |
</funcprototype> |
| 36 |
</funcsynopsis> |
| 37 |
</refsynopsisdiv> |
| 38 |
|
| 39 |
<refsect1> |
| 40 |
<title>Description</title> |
| 41 |
<para> |
| 42 |
Memory statistics are accessed through the |
| 43 |
<function>get_memory_stats</function> function. It returns a |
| 44 |
pointer to a static <structname>mem_stat_t</structname>. |
| 45 |
</para> |
| 46 |
<para> |
| 47 |
The <function>get_swap_stats</function> returns returns swap |
| 48 |
statistics. It returns a pointer to a static |
| 49 |
<structname>swap_stat_t</structname>. |
| 50 |
</para> |
| 51 |
<para> |
| 52 |
On the FreeBSD operating system elevated privileges are required |
| 53 |
to access the swap statistics. Making the program setgid kmem |
| 54 |
should be sufficient. Programs running as root will not have this |
| 55 |
problem. |
| 56 |
</para> |
| 57 |
</refsect1> |
| 58 |
|
| 59 |
<refsect1> |
| 60 |
<title>Return Values</title> |
| 61 |
|
| 62 |
<para> |
| 63 |
The VM system calls can return a pointer to either a |
| 64 |
<structname>mem_stat_t</structname> or a |
| 65 |
<structname>swap_stat_t</structname>. |
| 66 |
</para> |
| 67 |
|
| 68 |
<programlisting> |
| 69 |
typedef struct{ |
| 70 |
long long total; |
| 71 |
long long free; |
| 72 |
long long used; |
| 73 |
long long cache; |
| 74 |
}mem_stat_t; |
| 75 |
</programlisting> |
| 76 |
|
| 77 |
<variablelist> |
| 78 |
<varlistentry> |
| 79 |
<term> |
| 80 |
<structfield>total</structfield> |
| 81 |
</term> |
| 82 |
<listitem> |
| 83 |
<para> |
| 84 |
The total amount of memory in bytes. |
| 85 |
</para> |
| 86 |
</listitem> |
| 87 |
</varlistentry> |
| 88 |
<varlistentry> |
| 89 |
<term> |
| 90 |
<structfield>free</structfield> |
| 91 |
</term> |
| 92 |
<listitem> |
| 93 |
<para> |
| 94 |
The total free memory in bytes. |
| 95 |
</para> |
| 96 |
</listitem> |
| 97 |
</varlistentry> |
| 98 |
<varlistentry> |
| 99 |
<term> |
| 100 |
<structfield>used</structfield> |
| 101 |
</term> |
| 102 |
<listitem> |
| 103 |
<para> |
| 104 |
The total used memory in bytes. |
| 105 |
</para> |
| 106 |
</listitem> |
| 107 |
</varlistentry> |
| 108 |
<varlistentry> |
| 109 |
<term> |
| 110 |
<structfield>cache</structfield> |
| 111 |
</term> |
| 112 |
<listitem> |
| 113 |
<para> |
| 114 |
The amount of cache used in bytes. |
| 115 |
</para> |
| 116 |
</listitem> |
| 117 |
</varlistentry> |
| 118 |
</variablelist> |
| 119 |
|
| 120 |
<programlisting> |
| 121 |
typedef struct{ |
| 122 |
long long total; |
| 123 |
long long used; |
| 124 |
long long free; |
| 125 |
}swap_stat_t; |
| 126 |
</programlisting> |
| 127 |
|
| 128 |
<variablelist> |
| 129 |
<varlistentry> |
| 130 |
<term> |
| 131 |
<structfield>total</structfield> |
| 132 |
</term> |
| 133 |
<listitem> |
| 134 |
<para> |
| 135 |
The total swap space in bytes. |
| 136 |
</para> |
| 137 |
</listitem> |
| 138 |
</varlistentry> |
| 139 |
<varlistentry> |
| 140 |
<term> |
| 141 |
<structfield>used</structfield> |
| 142 |
</term> |
| 143 |
<listitem> |
| 144 |
<para> |
| 145 |
The used swap in bytes. |
| 146 |
</para> |
| 147 |
</listitem> |
| 148 |
</varlistentry> |
| 149 |
<varlistentry> |
| 150 |
<term> |
| 151 |
<structfield>free</structfield> |
| 152 |
</term> |
| 153 |
<listitem> |
| 154 |
<para> |
| 155 |
The free swap in bytes. |
| 156 |
</para> |
| 157 |
</listitem> |
| 158 |
</varlistentry> |
| 159 |
</variablelist> |
| 160 |
</refsect1> |
| 161 |
|
| 162 |
<refsect1> |
| 163 |
<title>Todo</title> |
| 164 |
<para> |
| 165 |
Add a function to hold open the file descriptor to the kernel |
| 166 |
memory structures. Doing this would allow the elevated privileges |
| 167 |
to be dropped early on. |
| 168 |
</para> |
| 169 |
</refsect1> |
| 170 |
|
| 171 |
<refsect1> |
| 172 |
<title>See Also</title> |
| 173 |
|
| 174 |
<simplelist type="inline"> |
| 175 |
<member> |
| 176 |
<citerefentry> |
| 177 |
<refentrytitle>statgrab</refentrytitle> |
| 178 |
<manvolnum>3</manvolnum> |
| 179 |
</citerefentry> |
| 180 |
</member> |
| 181 |
</simplelist> |
| 182 |
</refsect1> |
| 183 |
|
| 184 |
<refsect1> |
| 185 |
<title>Website</title> |
| 186 |
|
| 187 |
<simplelist type="vert"> |
| 188 |
<member> |
| 189 |
<ulink url="http://www.i-scream.org/libstatgrab/"> |
| 190 |
http://www.i-scream.org/libstatgrab/ |
| 191 |
</ulink> |
| 192 |
</member> |
| 193 |
</simplelist> |
| 194 |
</refsect1> |
| 195 |
|
| 196 |
</refentry> |
