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

<?xml version="1.0" encoding="utf-8"?>
<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</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 <citetitle>Using GConf</citetitle>.</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 Themes Which Require Less CPU Resources</title>
      <indexterm>
        <primary>themes</primary>
        <secondary>and CPU usage</secondary>
      </indexterm>
      <para>Some window frame themes load image files to draw the window frame.
Other themes use simpler techniques to draw the window frame.</para>
      <para>The default theme is Crux. Crux loads image files, and can be slow on
systems with limited CPU resources. To reduce CPU usage, use one of the following
window frame themes: </para>
      <itemizedlist>
        <listitem>
          <para>Atlanta</para>
        </listitem>
        <listitem>
          <para>Esco</para>
        </listitem>
      </itemizedlist>
      <para>The following window frame themes 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 desktop themes such as
HighContrastInverse. Use Atlanta with inverse desktop themes.</para>
      </note>
      <indexterm>
        <primary>themes</primary>
        <secondary>changing</secondary>
      </indexterm>
      <para>To change the window frame theme, run the following command: </para>
      <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type string
--set /apps/metacity/general/theme <replaceable>theme_name</replaceable></userinput></para>
      <para>For example, to use Atlanta, run the following command:</para>
      <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type string
--set /apps/metacity/general/theme Atlanta</userinput></para>
      <para>Alternatively, users can choose <menuchoice><guimenu>Applications</guimenu><guisubmenu>Desktop Preferences</guisubmenu><guimenuitem>Themes</guimenuitem></menuchoice>, then select the appropriate theme.</para>
      <tip>
        <para>You can use the <application>Metacity Theme Viewer</application>
to measure the performance of a window frame theme, and to preview the theme.
To start <application>Metacity Theme Viewer</application>, use the following
command:</para>
        <para><computeroutput>#</computeroutput> <userinput>metacity-theme-viewer <replaceable>theme_name</replaceable></userinput></para>
        <para>For example, to measure the performance of Atlanta and preview Atlanta,
run the following command: </para>
        <para><computeroutput>#</computeroutput> <userinput>metacity-theme-viewer
Atlanta</userinput></para>
      </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>
      <para>Some items in menus display an icon beside the item. To
turn off this feature, run the following command: </para>
      <indexterm>
        <primary>menu icons</primary>
        <secondary>turning off</secondary>
      </indexterm>
      <para><computeroutput>#</computeroutput> <userinput>gconftool-2
--type bool --set /desktop/gnome/interface/menus_have_icons false</userinput></para>
      <para>Alternatively, users can choose <menuchoice><guimenu>Applications</guimenu><guisubmenu>Desktop Preferences</guisubmenu><guimenuitem>Menus &amp; Toolbars</guimenuitem></menuchoice>, then deselect the <guilabel>Show icons in menus</guilabel> option.</para>
    </sect2>
    <sect2 id="performance-5">
      <title>To Reduce CPU Usage by Turning On Wireframe Mode</title>
      <indexterm>
        <primary>wireframe mode</primary>
        <secondary>and CPU usage</secondary>
      </indexterm>
      <para>The Metacity window manager has a wireframe mode for when
you move and resize windows. When wireframe mode is turned on, only the outline
of windows is displayed when you move and resize windows. The contents of
the window do not need to be updated during the move or resize. The contents
of the window are displayed when the move or resize is complete.</para>
      <indexterm>
        <primary>wireframe mode</primary>
        <secondary>turning on</secondary>
      </indexterm>
      <para>To turn on wireframe mode, run the following command:</para>
      <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type bool
--set /apps/metacity/general/wireframe_move_resize true</userinput></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 GNOME desktop, 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>
      <indexterm>
        <primary>splash screen</primary>
        <secondary>turning off</secondary>
      </indexterm>
      <para>To turn off the splash screen, run the following command:</para>
      <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type bool
--set /apps/gnome-session/options/show_splash_screen false</userinput></para>
      <para>Alternatively, users can choose <menuchoice><guimenu>Applications</guimenu><guisubmenu>Desktop Preferences</guisubmenu><guisubmenu>Advanced</guisubmenu><guimenuitem>Sessions</guimenuitem></menuchoice>,
then 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>
      <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type bool
--set /apps/panel/global/enable_animations false</userinput></para>
      <para>Alternatively, users can choose <menuchoice><guimenu>Applications</guimenu><guisubmenu>Desktop Preferences</guisubmenu><guisubmenu>Advanced</guisubmenu><guimenuitem>Themes</guimenuitem></menuchoice>,
then deselect the <guilabel>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 valign="top">
                  <para>Value</para>
                </entry>
                <entry valign="top">
                  <para>Description</para>
                </entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry>
                  <para>
                    <literal>always</literal>
                  </para>
                </entry>
                <entry>
                  <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 valign="top">
                  <para>Preference</para>
                </entry>
                <entry valign="top">
                  <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>
                  <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type string --set /apps/nautilus/preferences/show_icon_text
never</userinput></para>
                  <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>Performance</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>
                  <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type string --set /apps/nautilus/preferences/show_directory_item_counts
never </userinput></para>
                  <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>Performance</guilabel>.</para>
                    </listitem>
                    <listitem>
                      <para>Select an option for the <guilabel>Show Number of Items in
Folders</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>
                  <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type string --set /apps/nautilus/preferences/show_image_thumbnails
never </userinput></para>
                  <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>Performance</guilabel>.</para>
                    </listitem>
                    <listitem>
                      <para>Select an option for the <guilabel>Show Thumbnails for Image
Files</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>
                  <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type string --set /apps/nautilus/preferences/preview_sound
never </userinput></para>
                  <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>Performance</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>
        <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type bool
--set /apps/nautilus/preferences/start_with_sidebar false</userinput></para>
        <para>Alternatively, users can choose <menuchoice><guimenu>Edit</guimenu><guimenuitem>Preferences</guimenuitem></menuchoice> from a file manager window,
then choose <guilabel>Windows</guilabel>, and then deselect the <guilabel>Display side pane</guilabel> option. The next time that users open a file
manager window, the window does not display a side pane. </para>
        <indexterm>
          <primary>file manager</primary>
          <secondary>toolbar, turning off</secondary>
        </indexterm>
        <para>To turn off the toolbar, run the following command: </para>
        <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type bool
--set /apps/nautilus/preferences/start_with_toolbar false</userinput></para>
        <para>Alternatively, users can choose <menuchoice><guimenu>Edit</guimenu><guimenuitem>Preferences</guimenuitem></menuchoice> from a file manager window,
then choose <guilabel>Windows</guilabel>, and then deselect the <guilabel>Display toolbar</guilabel> option. The next time that users open a file manager
window, the window does not display a toolbar. </para>
        <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>
        <indexterm>
          <primary>file manager</primary>
          <secondary>location bar, turning
off</secondary>
        </indexterm>
        <para>To turn off the location bar, run the following
command:</para>
        <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type bool
--set /apps/nautilus/preferences/start_with_location_bar false</userinput></para>
        <para>Alternatively, users can choose <menuchoice><guimenu>Edit</guimenu><guimenuitem>Preferences</guimenuitem></menuchoice> from a file manager window,
then choose <guilabel>Windows</guilabel>, and then deselect the <guilabel>Display location bar</guilabel> option. The next time that users open a file
manager window, the window does not display a location bar.</para>
      </sect3>
      <sect3 id="performance-11">
        <title>To Turn Off the Desktop Background</title>
        <indexterm>
          <primary>file manager</primary>
          <secondary>desktop background, turning
off</secondary>
        </indexterm>
        <indexterm>
          <primary>desktop background</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 background. Users can disable the desktop background
to improve performance. However, if users disable the desktop background,
users cannot do the following:</para>
        <itemizedlist>
          <listitem>
            <para>Use the <guimenu>Desktop Background</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 <guilabel>Home</guilabel> object and the <guilabel>Trash</guilabel> object. The <guilabel>Home</guilabel> object and the <guilabel>Trash</guilabel> object are not displayed on the desktop. </para>
          </listitem>
        </itemizedlist>
        <para>To disable the desktop background, run the following command: </para>
        <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type bool
--set /apps/nautilus/preferences/show_desktop false</userinput></para>
        <para>Alternatively, users can choose <menuchoice><guimenu>Edit</guimenu><guimenuitem>Preferences</guimenuitem></menuchoice> from a file manager window.
Users can then choose <guilabel>Desktop &amp; Trash</guilabel>, and then deselect
the <guilabel>Use Nautilus to draw the desktop</guilabel> option. </para>
      </sect3>
    </sect2>
  </sect1>
  <sect1 id="performance-12">
    <title>Reducing X11 Network Traffic</title>
    <indexterm>
      <primary>reducing</primary>
      <secondary>X11 network traffic</secondary>
    </indexterm>
    <indexterm>
      <primary>X11 network traffic, reducing</primary>
    </indexterm>
    <indexterm>
      <primary>network traffic, reducing</primary>
    </indexterm>
    <para>This section describes preferences that you can set to reduce X11 network
traffic on the GNOME desktop. </para>
    <sect2 id="performance-14">
      <title>To Use Themes Which Create Less Network Traffic</title>
      <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 X11 network traffic, use a window frame theme that uses solid
colors. That is, use one of the following window frame themes:</para>
      <itemizedlist>
        <listitem>
          <para>Atlanta</para>
        </listitem>
        <listitem>
          <para>Esco</para>
        </listitem>
      </itemizedlist>
      <para>For information on how to change the theme, 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 X11
network traffic. This feature can also increase X11 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>
    <sect2 id="performance-13">
      <title>To Reduce Network Traffic by Turning On Wireframe Mode</title>
      <indexterm>
        <primary>wireframe mode</primary>
        <secondary>and network traffic</secondary>
      </indexterm>
      <para>If the application that displays the window
is running on a remote host, wireframe mode reduces X11 network traffic.</para>
      <para>For more information on wireframe mode, see <xref linkend="performance-5"/>.</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>Netscape 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 <application>Netscape</application> 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 <application>Netscape</application>
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 <application>Netscape</application> color palette, and applications
that do not use this palette. The applications that do not use the <application>Netscape</application> 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 Themes That Use the Netscape Color Palette</title>
      <indexterm>
        <primary>themes</primary>
        <secondary>and color usage</secondary>
      </indexterm>
      <para>Some window frame themes use colors that are in the Netscape
color palette. Bright and Esco use colors from the Netscape color palette.
Bright and Esco do not have the grainy appearance of other themes 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 the theme, 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 <application>Netscape</application>
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 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 Desktop Background</title>
      <indexterm>
        <primary>desktop 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 desktop background, run the following commands: </para>
      <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type string
--set /desktop/gnome/background/picture_options none</userinput></para>
      <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type string
--set /desktop/gnome/background/color_shading_type solid</userinput></para>
      <para><computeroutput>#</computeroutput> <userinput>gconftool-2 --type string
--set /desktop/gnome/background/primary_color \#<replaceable>hexadecimal_color</replaceable></userinput></para>
      <para>Alternatively, users can choose <menuchoice><guimenu>Applications</guimenu><guisubmenu>Desktop Preferences</guisubmenu><guimenuitem>Background</guimenuitem></menuchoice>, then choose a solid color for the desktop
background.</para>
    </sect2>
  </sect1>
</chapter>