libstatgrab/docs/get_diskio_stats.xml

<?xml version="1.0"?>

<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
               "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<refentry id="get_diskio_stats">

  <refentryinfo>
    <date>$Date: 2003/10/02 15:17:59 $</date>
    <releaseinfo>$Id: get_diskio_stats.xml,v 1.1 2003/10/02 15:17:59 tdb Exp $</releaseinfo>
  </refentryinfo>
  
  <refmeta>
    <refentrytitle>get_diskio_stats</refentrytitle>
    <manvolnum>3</manvolnum>
    <refmiscinfo>i-scream</refmiscinfo>
  </refmeta>
  
  <refnamediv>
    <refname>get_diskio_stats</refname>
    <refname>get_diskio_stats_diff</refname>
    <refpurpose>get disk io statistics</refpurpose>
  </refnamediv>
    
  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>#include &lt;statgrab.h&gt;</funcsynopsisinfo>
      <funcprototype>
        <funcdef>diskio_stat_t *<function>get_diskio_stats</function></funcdef>
        <paramdef>int *<parameter>entries</parameter></paramdef>
      </funcprototype>
      <funcprototype>
        <funcdef>diskio_stat_t *<function>get_diskio_stats_diff</function></funcdef>
        <paramdef>int *<parameter>entries</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>
    
  <refsect1>
    <title>Description</title>
    <para>
      Both calls take a pointer to an int,
      <parameter>entries</parameter>, which is filled with the number
      of disks the machine has. This is needed to know how many
      <structname>diskio_stat_t</structname> structures have been
      returned. A pointer is returned to the first
      <structname>diskio_stat_t</structname>.
    </para>
    <para>
      <function>get_diskio_stats</function> returns the disk IO stored
      in the kernel which holds the amount of data transferred since
      bootup. On some platforms, such as Solaris 7, this value is
      stored in a 32bit int, so wraps around when it reaches 4GB. Other
      platforms, such as Solaris 8, hold the value in a 64bit int,
      which wraps somewhere near 17 million terabytes.
    </para>
    <para>
      <function>get_diskio_stats_diff</function> is the same as
      <function>get_diskio_stats</function> except it will return the
      difference since the last call. So, for instance a call to
      <function>get_diskio_stats_diff</function> is made, and called
      again 5 seconds later. Over that time, 2000 bytes of traffic were
      written and 10000 bytes read.  <parameter>write_bytes</parameter>
      will store 2000 bytes, <parameter>read_bytes</parameter> will
      store 10000, and <parameter>systime</parameter> will store 5.
      This function copes with wrap arounds by the O/S so should be
      seemless to use.
    </para>
  </refsect1>
  
  <refsect1>
    <title>Return Values</title>

    <para>
      All diskio statistics return a pointer to a structure of type
      <structname>diskio_stat_t</structname>.
    </para>

    <programlisting>
typedef struct{
        char *disk_name;
        long long read_bytes;
        long long write_bytes;
        time_t systime;
}diskio_stat_t;
    </programlisting>

    <variablelist>
      <varlistentry>
        <term>
          <structfield>disk_name</structfield>
        </term>
        <listitem>
          <para>
            The name known to the operating system.
            (eg. on linux it might be hda)
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          <structfield>read_bytes</structfield>
        </term>
        <listitem>
          <para>
            The number of bytes the disk has read.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          <structfield>write_bytes</structfield>
        </term>
        <listitem>
          <para>
            The number of bytes the disk has written.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          <structfield>systime</structfield>
        </term>
        <listitem>
          <para>
            The time period over which <parameter>read_bytes</parameter>
            and <parameter>write_bytes</parameter> were transferred.
          </para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Bugs</title>
    <para>
      On the very first call <function>get_diskio_stats_diff</function>
      will return the same as <function>get_diskio_stats</function>.
      After the first call it will always return the difference.
    </para>
    <para>
      On operating systems that hold only 32bits of data there is a
      problem if the values wrap twice. For example, on Solaris 7 if
      9GB is transferred and the operating system wraps at 4GB, the
      <function>get_diskio_stats_diff</function> function will return
      5GB.
    </para>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>Nothing yet</para>
  </refsect1>
  
  <refsect1>
    <title>Website</title>
    
    <simplelist type="vert">
      <member>
        <ulink url="http://www.i-scream.org">http://www.i-scream.org</ulink>
      </member>
    </simplelist>
  </refsect1>

</refentry>
Revision:	1.2
Committed:	Thu Oct 2 16:01:52 2003 UTC (21 years, 1 month ago) by tdb
Content type:	text/xml
Branch:	MAIN
Changes since 1.1:	+4 -4 lines
Log Message:	Fix some markup.
#	User	Rev	Content
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	1.2	<date>$Date: 2003/10/02 15:17:59 $</date>
10			<releaseinfo>$Id: get_diskio_stats.xml,v 1.1 2003/10/02 15:17:59 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			</para>
69			</refsect1>
70
71			<refsect1>
72			<title>Return Values</title>
73
74			<para>
75			All diskio statistics return a pointer to a structure of type
76			<structname>diskio_stat_t</structname>.
77			</para>
78
79			<programlisting>
80			typedef struct{
81			char *disk_name;
82			long long read_bytes;
83			long long write_bytes;
84			time_t systime;
85			}diskio_stat_t;
86			</programlisting>
87
88			<variablelist>
89			<varlistentry>
90			<term>
91			<structfield>disk_name</structfield>
92			</term>
93			<listitem>
94			<para>
95			The name known to the operating system.
96			(eg. on linux it might be hda)
97			</para>
98			</listitem>
99			</varlistentry>
100			<varlistentry>
101			<term>
102			<structfield>read_bytes</structfield>
103			</term>
104			<listitem>
105			<para>
106			The number of bytes the disk has read.
107			</para>
108			</listitem>
109			</varlistentry>
110			<varlistentry>
111			<term>
112			<structfield>write_bytes</structfield>
113			</term>
114			<listitem>
115			<para>
116			The number of bytes the disk has written.
117			</para>
118			</listitem>
119			</varlistentry>
120			<varlistentry>
121			<term>
122			<structfield>systime</structfield>
123			</term>
124			<listitem>
125			<para>
126	tdb	1.2	The time period over which <parameter>read_bytes</parameter>
127			and <parameter>write_bytes</parameter> were transferred.
128	tdb	1.1	</para>
129			</listitem>
130			</varlistentry>
131			</variablelist>
132			</refsect1>
133
134			<refsect1>
135			<title>Bugs</title>
136			<para>
137			On the very first call <function>get_diskio_stats_diff</function>
138			will return the same as <function>get_diskio_stats</function>.
139			After the first call it will always return the difference.
140			</para>
141			<para>
142			On operating systems that hold only 32bits of data there is a
143			problem if the values wrap twice. For example, on Solaris 7 if
144			9GB is transferred and the operating system wraps at 4GB, the
145			<function>get_diskio_stats_diff</function> function will return
146			5GB.
147			</para>
148			</refsect1>
149
150			<refsect1>
151			<title>See Also</title>
152			<para>Nothing yet</para>
153			</refsect1>
154
155			<refsect1>
156			<title>Website</title>
157
158			<simplelist type="vert">
159			<member>
160			<ulink url="http://www.i-scream.org">http://www.i-scream.org</ulink>
161			</member>
162			</simplelist>
163			</refsect1>
164
165			</refentry>