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: 2004/03/11 17:35:24 $</date>
    <releaseinfo>$Id: get_diskio_stats.xml,v 1.5 2004/03/11 17:35:24 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>
    <para>
      On Solaris libstatgrab will attempt to get the cXtXdXsX
      representation for the <varname>disk_name</varname> string. If
      it fails it will use a name like sd0. On some systems programs
      calling libstatgrab will need elevated privileges to lookup
      some of the names. The mappings are built up when
      <function>statgrab_init</function> is called.
    </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>

    <simplelist type="inline">
      <member>
        <citerefentry>
          <refentrytitle>statgrab</refentrytitle>
          <manvolnum>3</manvolnum>
        </citerefentry>
      </member>
    </simplelist>
  </refsect1>
  
  <refsect1>
    <title>Website</title>
    
    <simplelist type="vert">
      <member>
        <ulink url="http://www.i-scream.org/libstatgrab/">
          http://www.i-scream.org/libstatgrab/
        </ulink>
      </member>
    </simplelist>
  </refsect1>

</refentry>
Revision:	1.6
Committed:	Sun May 2 09:35:15 2004 UTC (20 years ago) by tdb
Content type:	text/xml
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.5:	+2 -2 lines
State:	*FILE REMOVED*
Log Message:	Do a repo copy of the documentation to their new names, then delete the old ones. They still need their content updating though. We also need docs for the new process stats stuff, the error reporting code, and I think the FS stats which seem to be missing.
#	Content
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	<date>$Date: 2004/03/11 17:35:24 $</date>
10	<releaseinfo>$Id: get_diskio_stats.xml,v 1.5 2004/03/11 17:35:24 tdb Exp $</releaseinfo>
11	</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	<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	</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	The time period over which <parameter>read_bytes</parameter>
135	and <parameter>write_bytes</parameter> were transferred.
136	</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
161	<simplelist type="inline">
162	<member>
163	<citerefentry>
164	<refentrytitle>statgrab</refentrytitle>
165	<manvolnum>3</manvolnum>
166	</citerefentry>
167	</member>
168	</simplelist>
169	</refsect1>
170
171	<refsect1>
172	<title>Website</title>
173
174	<simplelist type="vert">
175	<member>
176	<ulink url="http://www.i-scream.org/libstatgrab/">
177	http://www.i-scream.org/libstatgrab/
178	</ulink>
179	</member>
180	</simplelist>
181	</refsect1>
182
183	</refentry>