path: root/gnome2-system-admin-guide/C/performance.xml

<chapter id="performance-0">
  <title>Improving Performance</title>
  <highlights>
    <para>This chapter describes how to improve the performance of
the GNOME Desktop.</para>
  </highlights>
  <sect1 id="performance-1">
    <title>Introduction to Improving Performance</title>
    <indexterm>
      <primary>performance, improving</primary>
      <secondary>introduction</secondary>
    </indexterm>
    <para>This chapter lists several preferences whose
settings you can change to improve the performance of the GNOME Desktop. You
can use the <command>gconftool-2</command> command to set values for preferences
for users. The example commands in this chapter show how to set values in
the user configuration source.</para>
    <para>You can also use the <literal>--direct</literal> and <literal>--config-source</literal> options to set mandatory values or default values for preferences.
You can also use the <command>gconftool-2</command> command in a script to
set the values of many preferences. For more information on the  <command>gconftool-2</command> command and the options that are  available with the
command, see <xref linkend="gconf-0"/>.</para>
  </sect1>
  <sect1 id="performance-8">
    <title>Reducing CPU Usage</title>
    <indexterm>
      <primary>performance, improving</primary>
      <secondary>reducing CPU
usage</secondary>
    </indexterm>
    <indexterm>
      <primary>reducing</primary>
      <secondary>CPU usage</secondary>
    </indexterm>
    <indexterm>
      <primary>CPU usage</primary>
      <secondary>reducing</secondary>
    </indexterm>
    <para>This section describes preferences that
you can set to reduce CPU usage by the GNOME Desktop. </para>
    <sect2 id="performance-3">
      <title>To Use Theme Options Which Require Less CPU Resources</title>
      <indexterm>
        <primary>themes</primary>
        <secondary>window frame options</secondary>
        <tertiary>and CPU usage</tertiary>
      </indexterm>
      <indexterm>
        <primary>themes</primary>
        <secondary>and CPU usage</secondary>
      </indexterm>
      <para>Some window frame theme
options load image files to draw the window frame. Other options use simpler
techniques to draw the window frame.</para>
      <para>The Crux window frame option loads image files, and can be slow on systems
with limited CPU resources. To reduce CPU usage, use one of the following
window frame options: </para>
      <itemizedlist>
        <listitem>
          <para>Atlanta</para>
        </listitem>
        <listitem>
          <para>Esco</para>
        </listitem>
      </itemizedlist>
      <para>The following window frame options also use less CPU resources than
Crux:</para>
      <itemizedlist>
        <listitem>
          <para>AgingGorilla</para>
        </listitem>
        <listitem>
          <para>Bright</para>
        </listitem>
        <listitem>
          <para>Metabox</para>
        </listitem>
      </itemizedlist>
      <note>
        <para>Metabox does not work well with inverse controls options such
as HighContrastInverse. Use Atlanta with inverse controls options.</para>
      </note>
      <para><indexterm><primary>themes</primary><secondary>window frame options</secondary><tertiary>changing</tertiary></indexterm>To change the window
frame theme option, run the following command: </para>
      <screen><userinput>gconftool-2 \
--type string \
--set /apps/metacity/general/theme <replaceable>option-name</replaceable></userinput></screen>
      <para>For example, to use Atlanta, run the following command:</para>
      <screen><userinput>gconftool-2 \
--type string \
--set /apps/metacity/general/theme Atlanta</userinput></screen>
      <para>Alternatively, users can use the <application>Theme</application> preference
tool to select the appropriate option.</para>
      <tip>
        <para>You can use the <application>Metacity Theme Viewer</application>
to measure the performance of a window frame option, and to preview the option.
To start <application>Metacity Theme Viewer</application>, use the following
command:</para>
        <screen><userinput>metacity-theme-viewer <replaceable>option-name</replaceable></userinput></screen>
        <para>For example, to measure the performance of Atlanta and preview Atlanta,
run the following command: </para>
        <screen><userinput>metacity-theme-viewer Atlanta</userinput></screen>
      </tip>
    </sect2>
    <sect2 id="performance-2">
      <title>To Reduce CPU Usage by Turning Off Display of Icons in Menus</title>
      <indexterm>
        <primary>icons, in menus</primary>
        <see>menu icons</see>
      </indexterm>
      <indexterm>
        <primary>menu icons</primary>
        <secondary>and CPU usage</secondary>
      </indexterm>
      <indexterm>
        <primary>menu icons</primary>
        <secondary>turning off</secondary>
      </indexterm>
      <para>Some items in menus display an icon beside the
item. To turn off this feature, run the following command: </para>
      <screen><userinput>gconftool-2 \
--type bool \
--set /desktop/gnome/interface/menus_have_icons false</userinput></screen>
      <para>Alternatively, users can use the <application>Menus &amp; Toolbars</application>
preference tool to deselect the <guilabel>Show icons in menus</guilabel> option.</para>
    </sect2>
    <sect2 id="performance-6">
      <title>To Reduce CPU Usage by Turning Off the Splash Screen</title>
      <indexterm>
        <primary>splash screen</primary>
        <secondary>and CPU usage</secondary>
      </indexterm>
      <para>By default, when users log in to the desktop environment,
a splash screen is displayed. Icons are displayed on the splash screen while
the user logs in. You can turn off the splash screen to reduce CPU usage during
login. </para>
      <para><indexterm><primary>splash screen</primary><secondary>turning off</secondary></indexterm>To turn off the splash screen, run the following command:</para>
      <screen><userinput>gconftool-2 \
--type bool \
--set /apps/gnome-session/options/show_splash_screen false</userinput></screen>
      <para>Alternatively, users can use the <application>Sessions</application>
preference tool to deselect the <guilabel>Show splash screen on login</guilabel>
option.</para>
    </sect2>
    <sect2 id="performance-4">
      <title>To Reduce CPU Usage by Turning Off Panel Animation</title>
      <indexterm>
        <primary>panels</primary>
        <secondary>animation, turning off</secondary>
      </indexterm>
      <para>When users show or hide panels, the panels can show or hide
in an animated style. To turn off panel animation, run the following command: </para>
      <screen><userinput>gconftool-2 \
--type bool \
--set /apps/panel/global/enable_animations false</userinput></screen>
      <para>Alternatively, users can use the <application>Panel</application> preference
tool to deselect the <guilabel>Drawer and panel animation</guilabel> option.</para>
    </sect2>
    <sect2 id="performance-7">
      <title>Improving File Manager Performance</title>
      <indexterm>
        <primary>Nautilus</primary>
        <see>file manager</see>
      </indexterm>
      <para>The <application>Nautilus</application> file manager includes some features
that you can modify to improve performance.</para>
      <sect3 id="performance-9">
        <title>To Modify Performance Preferences</title>
        <indexterm>
          <primary>file manager</primary>
          <secondary>modifying performance
preferences</secondary>
        </indexterm>
        <para>The file manager includes performance-related
preferences. Each performance preference can take one of three values. The
values are described in the following table:</para>
        <informaltable frame="topbot">
          <tgroup cols="2" colsep="0" rowsep="0">
            <colspec colwidth="34.46*"/>
            <colspec colwidth="65.54*"/>
            <thead>
              <row rowsep="1">
                <entry>
                  <para>Value</para>
                </entry>
                <entry>
                  <para>Description</para>
                </entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry valign="top">
                  <para>
                    <literal>always</literal>
                  </para>
                </entry>
                <entry valign="top">
                  <para>Performs the action for both local files, and files on
other file systems.</para>
                </entry>
              </row>
              <row>
                <entry valign="top">
                  <para>
                    <literal>local_only</literal>
                  </para>
                </entry>
                <entry valign="top">
                  <para>Performs the action for local files only. When you
set a performance preference to <literal>local_only</literal>, the CPU usage
is reduced.</para>
                </entry>
              </row>
              <row>
                <entry valign="top">
                  <para>
                    <literal>never</literal>
                  </para>
                </entry>
                <entry valign="top">
                  <para>Never performs the action. When you set a performance preference
to never, the CPU usage and the network traffic are reduced.</para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
        <para>The following table describes the performance preferences for the file
manager. For the fastest performance, set the value of the preferences to <literal>never</literal>.</para>
        <informaltable frame="topbot">
          <tgroup cols="2" colsep="0" rowsep="0">
            <colspec colwidth="43.34*"/>
            <colspec colwidth="56.66*"/>
            <thead>
              <row rowsep="1">
                <entry>
                  <para>Preference</para>
                </entry>
                <entry>
                  <para>Description</para>
                </entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry valign="top">
                  <para>
                    <literal>show_icon_text</literal>
                  </para>
                </entry>
                <entry valign="top">
                  <para>Specifies when to preview the content of text files
in the icon that represents the file. To never preview the content of text
files, run the following command: </para>
                  <screen><userinput>gconftool-2 \
--type string \
--set /apps/nautilus/preferences/show_icon_text never</userinput></screen>
                  <para>Alternatively, users can perform
the following steps:</para>
                  <orderedlist>
                    <listitem>
                      <para>Choose <menuchoice><guimenu>Edit</guimenu><guimenuitem>Preferences</guimenuitem></menuchoice> from a file manager window, then choose <guilabel>Preview</guilabel>.</para>
                    </listitem>
                    <listitem>
                      <para>Select an option for the <guilabel>Show text in icons</guilabel>
preference.</para>
                    </listitem>
                  </orderedlist>
                </entry>
              </row>
              <row>
                <entry valign="top">
                  <para>
                    <literal>show_directory_item_counts</literal>
                  </para>
                </entry>
                <entry valign="top">
                  <para>Specifies when to show the number of items in folders.
To never show the number of items in folders, run the following command:</para>
                  <screen><userinput>gconftool-2 \
--type string \
--set /apps/nautilus/preferences/show_directory_item_counts never</userinput></screen>
                  <para>Alternatively, users can perform the following steps:</para>
                  <orderedlist>
                    <listitem>
                      <para>Choose <menuchoice><guimenu>Edit</guimenu><guimenuitem>Preferences</guimenuitem></menuchoice> from a file manager window, then choose <guilabel>Preview</guilabel>.</para>
                    </listitem>
                    <listitem>
                      <para>Select an option for the <guilabel>Count number of items</guilabel>
preference.</para>
                    </listitem>
                  </orderedlist>
                </entry>
              </row>
              <row>
                <entry valign="top">
                  <para>
                    <literal>show_image_thumbnails</literal>
                  </para>
                </entry>
                <entry valign="top">
                  <para>Specifies when to show thumbnails of image files.
To never show thumbnails, run the following command:</para>
                  <screen><userinput>gconftool-2 \
--type string \
--set /apps/nautilus/preferences/show_image_thumbnails never</userinput></screen>
                  <para>Alternatively, users can perform the following steps:</para>
                  <orderedlist>
                    <listitem>
                      <para>Choose <menuchoice><guimenu>Edit</guimenu><guimenuitem>Preferences</guimenuitem></menuchoice> from a file manager window, then choose <guilabel>Preview</guilabel>.</para>
                    </listitem>
                    <listitem>
                      <para>Select an option for the <guilabel>Show thumbnails</guilabel>
preference.</para>
                    </listitem>
                  </orderedlist>
                </entry>
              </row>
              <row>
                <entry valign="top">
                  <para>
                    <literal>preview_sound</literal>
                  </para>
                </entry>
                <entry valign="top">
                  <para>Specifies when to preview the content of sound files.
To never preview the content of sound files, run the following command:</para>
                  <screen><userinput>gconftool-2 \
--type string \
--set /apps/nautilus/preferences/preview_sound never</userinput></screen>
                  <para>Alternatively, users can perform the following
steps:</para>
                  <orderedlist>
                    <listitem>
                      <para>Choose <menuchoice><guimenu>Edit</guimenu><guimenuitem>Preferences</guimenuitem></menuchoice> from a file manager window, then choose <guilabel>Preview</guilabel>.</para>
                    </listitem>
                    <listitem>
                      <para>Select an option for the <guilabel>Preview sound files</guilabel>
preference.</para>
                    </listitem>
                  </orderedlist>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </informaltable>
      </sect3>
      <sect3 id="performance-10">
        <title>To Turn Off the Side Pane, Toolbar, and Location Bar</title>
        <indexterm>
          <primary>file manager</primary>
          <secondary>side pane, turning off</secondary>
        </indexterm>
        <para>The file manager includes preferences that enable
you to turn off the side pane and the toolbar. To improve file manager performance,
turn off the side pane and the toolbar.</para>
        <para>To turn off the side pane, run the following command: </para>
        <screen><userinput>gconftool-2 \
--type bool \
--set /apps/nautilus/preferences/start_with_sidebar false</userinput></screen>
        <para><indexterm><primary>file manager</primary><secondary>toolbar, turning
off</secondary></indexterm>To turn off the toolbar, run the following command: </para>
        <screen><userinput>gconftool-2 \
--type bool \
--set /apps/nautilus/preferences/start_with_toolbar false</userinput></screen>
        <para>You can also turn off the location bar. Users can use the <keycombo><keycap>Ctrl</keycap><keycap>L</keycap></keycombo> keyboard shortcut to display a location bar
when required.  </para>
        <para><indexterm><primary>file manager</primary><secondary>location bar, turning
off</secondary></indexterm>To turn off the location bar, run the following
command:</para>
        <screen><userinput>gconftool-2 \
--type bool \
--set /apps/nautilus/preferences/start_with_location_bar false</userinput></screen>
      </sect3>
      <sect3 id="performance-11">
        <title>To Turn Off the Desktop</title>
        <indexterm>
          <primary>file manager</primary>
          <secondary>desktop, turning off</secondary>
        </indexterm>
        <indexterm>
          <primary>desktop</primary>
          <secondary>turning
off</secondary>
        </indexterm>
        <para>The file manager contains a preference that
enables users to use <application>Nautilus</application> to manage the desktop.
You can disable the desktop to improve performance. However, if you disable
the desktop, you cannot do the following:</para>
        <itemizedlist>
          <listitem>
            <para>Use the <guimenu>Desktop</guimenu> menu.</para>
          </listitem>
          <listitem>
            <para>Use the file manager to change the pattern or color of the
desktop background. </para>
          </listitem>
          <listitem>
            <para>Use the desktop objects, such as <guilabel>Trash</guilabel>.
The desktop objects are not displayed on the desktop. </para>
          </listitem>
        </itemizedlist>
        <para>To disable the desktop, run the following command: </para>
        <screen><userinput>gconftool-2 \
--type bool \
--set /apps/nautilus/preferences/show_desktop false</userinput></screen>
      </sect3>
    </sect2>
  </sect1>
  <sect1 id="performance-12">
    <title>Reducing X Window System Network Traffic</title>
    <indexterm>
      <primary>reducing</primary>
      <secondary>X Window System network traffic</secondary>
    </indexterm>
    <indexterm>
      <primary>X Window System network traffic,
reducing</primary>
    </indexterm>
    <indexterm>
      <primary>network traffic, reducing</primary>
    </indexterm>
    <para>This section describes preferences that you can
set to reduce X Window System network traffic on the GNOME Desktop. </para>
    <sect2 id="performance-14">
      <title>To Use Theme Options Which Create Less Network Traffic</title>
      <indexterm>
        <primary>themes</primary>
        <secondary>window frame options</secondary>
        <tertiary>and network traffic</tertiary>
      </indexterm>
      <indexterm>
        <primary>themes</primary>
        <secondary>and network traffic</secondary>
      </indexterm>
      <para>Remote
display protocols do not transfer every pixel in a block of pixels if all
pixels in the block are the same color.</para>
      <para>To reduce X Window System network traffic, use a window frame theme
option that uses solid colors. That is, use one of the following window frame
options:</para>
      <itemizedlist>
        <listitem>
          <para>Atlanta</para>
        </listitem>
        <listitem>
          <para>Esco</para>
        </listitem>
      </itemizedlist>
      <para>For information on how to change theme options, see <xref linkend="performance-3"/>.</para>
    </sect2>
    <sect2 id="performance-15">
      <title>To Reduce Network Traffic by Turning Off Display of Icons in Menus</title>
      <indexterm>
        <primary>menu icons</primary>
        <secondary>and network traffic</secondary>
      </indexterm>
      <para>Some items in menus display an icon beside the item. If
the icon is located on another file system, this feature can increase X Window
System network traffic. This feature can also increase X Window System network
traffic if the panels are displayed on a remote host. </para>
      <para>For information on how to turn off this feature, see <xref linkend="performance-2"/>.</para>
    </sect2>
  </sect1>
  <sect1 id="performance-17">
    <title>Reducing Color Usage and Improving Display Quality</title>
    <indexterm>
      <primary>reducing</primary>
      <secondary>color usage</secondary>
    </indexterm>
    <indexterm>
      <primary>color usage</primary>
      <secondary>reducing</secondary>
    </indexterm>
    <indexterm>
      <primary>display quality, improving</primary>
    </indexterm>
    <para>Many modern computer systems support 24-bit color, that is, 16,777,216 colors.
However, many users still use systems that support 8-bit color, that is, 256
colors. </para>
    <para>The GNOME Desktop uses the <firstterm>websafe color palette</firstterm>.
This palette is a general-purpose palette of 216 colors, which is designed
to optimize the use of color on systems that support 8-bit color. However,
some visual components of the GNOME Desktop are designed for systems that
support 24-bit color.</para>
    <para>The following display problems might occur on systems that support 8-bit
color:</para>
    <itemizedlist>
      <listitem>
        <para>Windows, icons, and background images might appear grainy.
 Many themes, background images, and icons use colors that are not in the
websafe color palette. The colors that are not in the palette are replaced
with the nearest equivalent or a dithered approximation. This use of replacement
colors causes the grainy appearance.</para>
      </listitem>
      <listitem>
        <para>Applications that do not use the websafe color palette have
less colors available. Color errors might occur. Some colors might not appear
in the user interface of the application. Some applications might crash if
the application cannot allocate colors.</para>
      </listitem>
      <listitem>
        <para>Color flashing might occur when users switch between applications
that use the websafe color palette, and applications that do not use this
palette. The applications that do not use the websafe color palette might
use a custom colormap. When the custom colormap is used, other visual components
might lose colors, then become unviewable.</para>
      </listitem>
    </itemizedlist>
    <para>The following sections describe how to optimize the appearance of the
GNOME Desktop for systems that support 8-bit color. </para>
    <sect2 id="performance-20">
      <title>To Use Theme Options That Use the Websafe Color Palette</title>
      <indexterm>
        <primary>themes</primary>
        <secondary>window frame options</secondary>
        <tertiary>and color usage</tertiary>
      </indexterm>
      <indexterm>
        <primary>themes</primary>
        <secondary>and color usage</secondary>
      </indexterm>
      <para>Some window
frame theme options use colors that are in the websafe color palette. Bright
and Esco use colors from the websafe color palette. Bright and Esco do not
have the grainy appearance of other window frame options on 8-bit color displays.
Use Bright or Esco for the best color display on 8-bit visual modes. </para>
      <para>For information on how to change theme options, see <xref linkend="performance-3"/>.</para>
    </sect2>
    <sect2 id="performance-21">
      <title>To Reduce Color Usage by Turning Off Display of Icons in Menus</title>
      <indexterm>
        <primary>menu icons</primary>
        <secondary>and color usage</secondary>
      </indexterm>
      <para>Some items in menus display an icon beside the item. If
the icon contains colors that are not in the websafe color palette, this feature
can increase the number of colors used.</para>
      <para>For information on how to turn off this feature, see <xref linkend="performance-2"/>.</para>
    </sect2>
    <sect2 id="performance-18">
      <title>To Reduce Color Usage by Turning Off the Splash Screen</title>
      <indexterm>
        <primary>splash screen</primary>
        <secondary>and color usage</secondary>
      </indexterm>
      <para>You can turn off the splash screen to make more colors available
for the GNOME Desktop and for applications.</para>
      <para>For information on how to turn off the splash screen, see <xref linkend="performance-6"/>.</para>
    </sect2>
    <sect2 id="performance-19">
      <title>To Reduce Color Usage by Using a Solid Color for the Background</title>
      <indexterm>
        <primary>background</primary>
        <secondary>using solid color</secondary>
      </indexterm>
      <para>Use a solid color for the desktop background. Use of a solid
color reduces the number of colors used by the GNOME Desktop. </para>
      <para>To set a solid color for the background, run the following commands: </para>
      <screen><userinput>gconftool-2 \
--type string \
--set /desktop/gnome/background/picture_options none</userinput></screen>
      <screen><userinput>gconftool-2 \
--type string \
--set /desktop/gnome/background/color_shading_type solid</userinput></screen>
      <screen><userinput>gconftool-2 \
--type string \
--set /desktop/gnome/background/primary_color #<replaceable>hexadecimal-color</replaceable></userinput></screen>
      <para>Alternatively, users can use the <application>Background</application>
preference tool to choose a solid color for the background.</para>
    </sect2>
  </sect1>
</chapter>