| 1 |
tdb |
1.1 |
<?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_diskio_stats"> |
| 7 |
|
|
|
| 8 |
|
|
<refentryinfo> |
| 9 |
tdb |
1.4 |
<date>$Date: 2003/10/02 17:38:03 $</date> |
| 10 |
|
|
<releaseinfo>$Id: get_diskio_stats.xml,v 1.3 2003/10/02 17:38:03 tdb Exp $</releaseinfo> |
| 11 |
tdb |
1.1 |
</refentryinfo> |
| 12 |
|
|
|
| 13 |
|
|
<refmeta> |
| 14 |
|
|
<refentrytitle>get_diskio_stats</refentrytitle> |
| 15 |
|
|
<manvolnum>3</manvolnum> |
| 16 |
|
|
<refmiscinfo>i-scream</refmiscinfo> |
| 17 |
|
|
</refmeta> |
| 18 |
|
|
|
| 19 |
|
|
<refnamediv> |
| 20 |
|
|
<refname>get_diskio_stats</refname> |
| 21 |
|
|
<refname>get_diskio_stats_diff</refname> |
| 22 |
|
|
<refpurpose>get disk io statistics</refpurpose> |
| 23 |
|
|
</refnamediv> |
| 24 |
|
|
|
| 25 |
|
|
<refsynopsisdiv> |
| 26 |
|
|
<funcsynopsis> |
| 27 |
|
|
<funcsynopsisinfo>#include <statgrab.h></funcsynopsisinfo> |
| 28 |
|
|
<funcprototype> |
| 29 |
|
|
<funcdef>diskio_stat_t *<function>get_diskio_stats</function></funcdef> |
| 30 |
|
|
<paramdef>int *<parameter>entries</parameter></paramdef> |
| 31 |
|
|
</funcprototype> |
| 32 |
|
|
<funcprototype> |
| 33 |
|
|
<funcdef>diskio_stat_t *<function>get_diskio_stats_diff</function></funcdef> |
| 34 |
|
|
<paramdef>int *<parameter>entries</parameter></paramdef> |
| 35 |
|
|
</funcprototype> |
| 36 |
|
|
</funcsynopsis> |
| 37 |
|
|
</refsynopsisdiv> |
| 38 |
|
|
|
| 39 |
|
|
<refsect1> |
| 40 |
|
|
<title>Description</title> |
| 41 |
|
|
<para> |
| 42 |
|
|
Both calls take a pointer to an int, |
| 43 |
|
|
<parameter>entries</parameter>, which is filled with the number |
| 44 |
|
|
of disks the machine has. This is needed to know how many |
| 45 |
|
|
<structname>diskio_stat_t</structname> structures have been |
| 46 |
|
|
returned. A pointer is returned to the first |
| 47 |
|
|
<structname>diskio_stat_t</structname>. |
| 48 |
|
|
</para> |
| 49 |
|
|
<para> |
| 50 |
|
|
<function>get_diskio_stats</function> returns the disk IO stored |
| 51 |
|
|
in the kernel which holds the amount of data transferred since |
| 52 |
|
|
bootup. On some platforms, such as Solaris 7, this value is |
| 53 |
|
|
stored in a 32bit int, so wraps around when it reaches 4GB. Other |
| 54 |
|
|
platforms, such as Solaris 8, hold the value in a 64bit int, |
| 55 |
|
|
which wraps somewhere near 17 million terabytes. |
| 56 |
|
|
</para> |
| 57 |
|
|
<para> |
| 58 |
|
|
<function>get_diskio_stats_diff</function> is the same as |
| 59 |
|
|
<function>get_diskio_stats</function> except it will return the |
| 60 |
|
|
difference since the last call. So, for instance a call to |
| 61 |
|
|
<function>get_diskio_stats_diff</function> is made, and called |
| 62 |
|
|
again 5 seconds later. Over that time, 2000 bytes of traffic were |
| 63 |
|
|
written and 10000 bytes read. <parameter>write_bytes</parameter> |
| 64 |
|
|
will store 2000 bytes, <parameter>read_bytes</parameter> will |
| 65 |
|
|
store 10000, and <parameter>systime</parameter> will store 5. |
| 66 |
|
|
This function copes with wrap arounds by the O/S so should be |
| 67 |
|
|
seemless to use. |
| 68 |
tdb |
1.4 |
</para> |
| 69 |
|
|
<para> |
| 70 |
|
|
On Solaris libstatgrab will attempt to get the cXtXdXsX |
| 71 |
|
|
representation for the <varname>disk_name</varname> string. If |
| 72 |
|
|
it fails it will use a name like sd0. On some systems programs |
| 73 |
|
|
calling libstatgrab will need elevated privileges to lookup |
| 74 |
|
|
some of the names. The mappings are built up when |
| 75 |
|
|
<function>statgrab_init</function> is called. |
| 76 |
tdb |
1.1 |
</para> |
| 77 |
|
|
</refsect1> |
| 78 |
|
|
|
| 79 |
|
|
<refsect1> |
| 80 |
|
|
<title>Return Values</title> |
| 81 |
|
|
|
| 82 |
|
|
<para> |
| 83 |
|
|
All diskio statistics return a pointer to a structure of type |
| 84 |
|
|
<structname>diskio_stat_t</structname>. |
| 85 |
|
|
</para> |
| 86 |
|
|
|
| 87 |
|
|
<programlisting> |
| 88 |
|
|
typedef struct{ |
| 89 |
|
|
char *disk_name; |
| 90 |
|
|
long long read_bytes; |
| 91 |
|
|
long long write_bytes; |
| 92 |
|
|
time_t systime; |
| 93 |
|
|
}diskio_stat_t; |
| 94 |
|
|
</programlisting> |
| 95 |
|
|
|
| 96 |
|
|
<variablelist> |
| 97 |
|
|
<varlistentry> |
| 98 |
|
|
<term> |
| 99 |
|
|
<structfield>disk_name</structfield> |
| 100 |
|
|
</term> |
| 101 |
|
|
<listitem> |
| 102 |
|
|
<para> |
| 103 |
|
|
The name known to the operating system. |
| 104 |
|
|
(eg. on linux it might be hda) |
| 105 |
|
|
</para> |
| 106 |
|
|
</listitem> |
| 107 |
|
|
</varlistentry> |
| 108 |
|
|
<varlistentry> |
| 109 |
|
|
<term> |
| 110 |
|
|
<structfield>read_bytes</structfield> |
| 111 |
|
|
</term> |
| 112 |
|
|
<listitem> |
| 113 |
|
|
<para> |
| 114 |
|
|
The number of bytes the disk has read. |
| 115 |
|
|
</para> |
| 116 |
|
|
</listitem> |
| 117 |
|
|
</varlistentry> |
| 118 |
|
|
<varlistentry> |
| 119 |
|
|
<term> |
| 120 |
|
|
<structfield>write_bytes</structfield> |
| 121 |
|
|
</term> |
| 122 |
|
|
<listitem> |
| 123 |
|
|
<para> |
| 124 |
|
|
The number of bytes the disk has written. |
| 125 |
|
|
</para> |
| 126 |
|
|
</listitem> |
| 127 |
|
|
</varlistentry> |
| 128 |
|
|
<varlistentry> |
| 129 |
|
|
<term> |
| 130 |
|
|
<structfield>systime</structfield> |
| 131 |
|
|
</term> |
| 132 |
|
|
<listitem> |
| 133 |
|
|
<para> |
| 134 |
tdb |
1.2 |
The time period over which <parameter>read_bytes</parameter> |
| 135 |
|
|
and <parameter>write_bytes</parameter> were transferred. |
| 136 |
tdb |
1.1 |
</para> |
| 137 |
|
|
</listitem> |
| 138 |
|
|
</varlistentry> |
| 139 |
|
|
</variablelist> |
| 140 |
|
|
</refsect1> |
| 141 |
|
|
|
| 142 |
|
|
<refsect1> |
| 143 |
|
|
<title>Bugs</title> |
| 144 |
|
|
<para> |
| 145 |
|
|
On the very first call <function>get_diskio_stats_diff</function> |
| 146 |
|
|
will return the same as <function>get_diskio_stats</function>. |
| 147 |
|
|
After the first call it will always return the difference. |
| 148 |
|
|
</para> |
| 149 |
|
|
<para> |
| 150 |
|
|
On operating systems that hold only 32bits of data there is a |
| 151 |
|
|
problem if the values wrap twice. For example, on Solaris 7 if |
| 152 |
|
|
9GB is transferred and the operating system wraps at 4GB, the |
| 153 |
|
|
<function>get_diskio_stats_diff</function> function will return |
| 154 |
|
|
5GB. |
| 155 |
|
|
</para> |
| 156 |
|
|
</refsect1> |
| 157 |
|
|
|
| 158 |
|
|
<refsect1> |
| 159 |
|
|
<title>See Also</title> |
| 160 |
tdb |
1.3 |
|
| 161 |
|
|
<simplelist type="inline"> |
| 162 |
|
|
<member> |
| 163 |
|
|
<citerefentry> |
| 164 |
|
|
<refentrytitle>statgrab</refentrytitle> |
| 165 |
|
|
<manvolnum>3</manvolnum> |
| 166 |
|
|
</citerefentry> |
| 167 |
|
|
</member> |
| 168 |
|
|
</simplelist> |
| 169 |
tdb |
1.1 |
</refsect1> |
| 170 |
|
|
|
| 171 |
|
|
<refsect1> |
| 172 |
|
|
<title>Website</title> |
| 173 |
|
|
|
| 174 |
|
|
<simplelist type="vert"> |
| 175 |
|
|
<member> |
| 176 |
|
|
<ulink url="http://www.i-scream.org">http://www.i-scream.org</ulink> |
| 177 |
|
|
</member> |
| 178 |
|
|
</simplelist> |
| 179 |
|
|
</refsect1> |
| 180 |
|
|
|
| 181 |
|
|
</refentry> |
