runtime.sgml

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

    semaphores can be in a set, must be at least 17 for
    <productname>PostgreSQL</>.
   </para>

   <para>
    Various other settings related to <quote>semaphore undo</>, such as
    <varname>SEMMNU</> and <varname>SEMUME</>, are not of concern
    for <productname>PostgreSQL</>.
   </para>


    <variablelist>

     <varlistentry>
      <term><systemitem class="osname">BSD/OS</></term>
      <indexterm><primary>BSD/OS</><secondary>IPC configuration</></>
      <listitem>
       <formalpara>
        <title>Shared Memory</>
        <para>
         By default, only 4 MB of shared memory is supported. Keep in
         mind that shared memory is not pageable; it is locked in RAM.
         To increase the amount of shared memory supported by your
         system, add something like the following to your kernel configuration
         file:
<programlisting>
options "SHMALL=8192"
options "SHMMAX=\(SHMALL*PAGE_SIZE\)"
</programlisting>
         <varname>SHMALL</> is measured in 4KB pages, so a value of
         1024 represents 4 MB of shared memory. Therefore the above increases
         the maximum shared memory area to 32 MB.
         For those running 4.3 or later, you will probably also need to increase
         <varname>KERNEL_VIRTUAL_MB</> above the default <literal>248</>.
         Once all changes have been made, recompile the kernel, and reboot.
        </para>
       </formalpara>

       <para>
        For those running 4.0 and earlier releases, use <command>bpatch</>
        to find the <varname>sysptsize</> value in the current
        kernel. This is computed dynamically at boot time.
<screen>
$ <userinput>bpatch -r sysptsize</>
<computeroutput>0x9 = 9</>
</screen>
        Next, add <varname>SYSPTSIZE</> as a hard-coded value in the
        kernel configuration file. Increase the value you found using
        <command>bpatch</>. Add 1 for every additional 4 MB of
        shared memory you desire.
<programlisting>
options "SYSPTSIZE=16"
</programlisting>
        <varname>sysptsize</> cannot be changed by <command>sysctl</command>.
       </para>

       <formalpara>
        <title>Semaphores</>
        <para>
         You will probably want to increase the number of semaphores
         as well; the default system total of 60 will only allow about
         50 <productname>PostgreSQL</productname> connections.  Set the
         values you want in your kernel configuration file, e.g.:
<programlisting>
options "SEMMNI=40"
options "SEMMNS=240"
</programlisting>
        </para>
       </formalpara>
      </listitem>
     </varlistentry>


     <varlistentry>
      <term><systemitem class="osname">FreeBSD</></term>
      <indexterm><primary>FreeBSD</><secondary>IPC configuration</></>
      <listitem>
       <para>
        The default settings are only suitable for small installations
        (for example, default <varname>SHMMAX</varname> is 32
        MB). Changes can be made via the <command>sysctl</command> or
        <command>loader</command> interfaces.  The following
        parameters can be set using <command>sysctl</command>:
<screen>
<prompt>$</prompt> <userinput>sysctl -w kern.ipc.shmall=32768</userinput>
<prompt>$</prompt> <userinput>sysctl -w kern.ipc.shmmax=134217728</userinput>
<prompt>$</prompt> <userinput>sysctl -w kern.ipc.semmap=256</userinput>
</screen>
        To have these settings persist over reboots, modify
        <filename>/etc/sysctl.conf</filename>.
       </para>

       <para>
        The remaining semaphore settings are read-only as far as
        <command>sysctl</command> is concerned, but can be changed
        before boot using the <command>loader</command> prompt:
<screen>
<prompt>(loader)</prompt> <userinput>set kern.ipc.semmni=256</userinput>
<prompt>(loader)</prompt> <userinput>set kern.ipc.semmns=512</userinput>
<prompt>(loader)</prompt> <userinput>set kern.ipc.semmnu=256</userinput>
</screen>
        Similarly these can be saved between reboots in
        <filename>/boot/loader.conf</filename>.
       </para>

       <para>
        You might also want to configure your kernel to lock shared
        memory into RAM and prevent it from being paged out to swap.
        This can be accomplished using the <command>sysctl</command>
        setting <literal>kern.ipc.shm_use_phys</literal>.
       </para>

       <para>
        If running in FreeBSD jails by enabling <application>sysctl</>'s
        <literal>security.jail.sysvipc_allowed</>, <application>postmaster</>s
        running in different jails should be run by different operating system
        users.  This improves security because it prevents non-root users
        from interfering with shared memory or semaphores in a different jail,
        and it allows the PostgreSQL IPC cleanup code to function properly.
        (In FreeBSD 6.0 and later the IPC cleanup code doesn't properly detect
        processes in other jails, preventing the running of postmasters on the
        same port in different jails.)
       </para>

       <para>
        <systemitem class="osname">FreeBSD</> versions before 4.0 work like 
        <systemitem class="osname">NetBSD</> and <systemitem class="osname">
        OpenBSD</> (see below).
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><systemitem class="osname">NetBSD</></term>
      <term><systemitem class="osname">OpenBSD</></term>
      <indexterm><primary>NetBSD</><secondary>IPC configuration</></>
      <indexterm><primary>OpenBSD</><secondary>IPC configuration</></>
      <listitem>
       <para>
        The options <varname>SYSVSHM</> and <varname>SYSVSEM</> need
        to be enabled when the kernel is compiled. (They are by
        default.) The maximum size of shared memory is determined by
        the option <varname>SHMMAXPGS</> (in pages). The following
        shows an example of how to set the various parameters 
        (<systemitem class="osname">OpenBSD</> uses <literal>option</> instead):
<programlisting>
options        SYSVSHM
options        SHMMAXPGS=4096
options        SHMSEG=256

options        SYSVSEM
options        SEMMNI=256
options        SEMMNS=512
options        SEMMNU=256
options        SEMMAP=256
</programlisting>
       </para>

       <para>
        You might also want to configure your kernel to lock shared
        memory into RAM and prevent it from being paged out to swap.
        This can be accomplished using the <command>sysctl</command>
        setting <literal>kern.ipc.shm_use_phys</literal>.
       </para>
      </listitem>
     </varlistentry>


     <varlistentry>
      <term><systemitem class="osname">HP-UX</></term>
      <indexterm><primary>HP-UX</><secondary>IPC configuration</></>
      <listitem>
       <para>
        The default settings tend to suffice for normal installations.
        On <productname>HP-UX</> 10, the factory default for
        <varname>SEMMNS</> is 128, which might be too low for larger
        database sites.
       </para>
       <para>
        <acronym>IPC</> parameters can be set in the <application>System
        Administration Manager</> (<acronym>SAM</>) under
        <menuchoice><guimenu>Kernel
        Configuration</><guimenuitem>Configurable Parameters</></>. Hit
        <guibutton>Create A New Kernel</> when you're done.
       </para>
      </listitem>
     </varlistentry>


     <varlistentry>
      <term><systemitem class="osname">Linux</></term>
      <indexterm><primary>Linux</><secondary>IPC configuration</></>
      <listitem>
       <para>
        The default settings are only suitable for small installations 
        (the default max segment size is 32 MB). However the remaining
        defaults are quite generously sized, and usually do not require
        changes. The max segment size can be changed via the 
        <command>sysctl</command> interface. For example, to allow 128 MB, 
        and explicitly set the maximum total shared memory size to 2097152 
        pages (the default):
<screen>
<prompt>$</prompt> <userinput>sysctl -w kernel.shmmax=134217728</userinput>
<prompt>$</prompt> <userinput>sysctl -w kernel.shmall=2097152</userinput>
</screen>
        In addition these settings can be saved between reboots in 
        <filename>/etc/sysctl.conf</filename>.
       </para>

       <para>
        Older distributions may not have the <command>sysctl</command> program,
        but equivalent changes can be made by manipulating the 
        <filename>/proc</filename> file system:
<screen>
<prompt>$</prompt> <userinput>echo 134217728 &gt;/proc/sys/kernel/shmmax</userinput>
<prompt>$</prompt> <userinput>echo 2097152 &gt;/proc/sys/kernel/shmall</userinput>
</screen>
       </para>
      </listitem>
     </varlistentry>


     <varlistentry>
      <term><systemitem class="osname">MacOS X</></term>
      <indexterm><primary>MacOS X</><secondary>IPC configuration</></>
      <listitem>
       <para>
        In OS X 10.2 and earlier, edit the file
        <filename>/System/Library/StartupItems/SystemTuning/SystemTuning</>
        and change the values in the following commands:
<programlisting>
sysctl -w kern.sysv.shmmax
sysctl -w kern.sysv.shmmin
sysctl -w kern.sysv.shmmni
sysctl -w kern.sysv.shmseg
sysctl -w kern.sysv.shmall
</programlisting>
        In OS X 10.3 and later, these commands have been moved to
        <filename>/etc/rc</> and must be edited there.  Note that
        <filename>/etc/rc</> is usually overwritten by OS X updates (such as
        10.3.6 to 10.3.7) so you should expect to have to redo your editing
        after each update.  In all versions, you'll need to reboot to make
        changes take effect.  
       </para>

       <para>
        In OS X 10.3.9 and later, the file <filename>/etc/sysctl.conf</>
        allows shared memory setting to be saved across operating system
        upgrades, and is the recommended method for setting these
        parameters. When using this file, all five shared memory values
        must be set or the changes will be ignored.
       </para>

       <para>
        <varname>SHMALL</> is measured in 4KB pages on this platform,
        and recent releases of OS X reject attempts to set 
        <varname>SHMALL</> and <varname>SHMMAX</> to a value 
        that isn't an exact multiple of 4096.
       </para>
      </listitem>
     </varlistentry>


     <varlistentry>
      <term><systemitem class="osname">SCO OpenServer</></term>
      <indexterm><primary>SCO OpenServer</><secondary>IPC configuration</></>
      <listitem>
       <para>
        In the default configuration, only 512 kB of shared memory per
        segment is allowed. To increase the setting, first change to the
        directory <filename>/etc/conf/cf.d</>. To display the current value of
        <varname>SHMMAX</>, run
<programlisting>
./configure -y SHMMAX
</programlisting>
        To set a new value for <varname>SHMMAX</>, run
<programlisting>
./configure SHMMAX=<replaceable>value</>
</programlisting>
        where <replaceable>value</> is the new value you want to use
        (in bytes). After setting <varname>SHMMAX</>, rebuild the kernel:
<programlisting>
./link_unix
</programlisting>
        and reboot.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><systemitem class="osname">AIX</></term>
      <indexterm><primary>AIX</><secondary>IPC configuration</></>
      <listitem>
       <para>
        At least as of version 5.1, it should not be necessary to do
        any special configuration for such parameters as
        <varname>SHMMAX</varname>, as it appears this is configured to
        allow all memory to be used as shared memory.  That is the
        sort of configuration commonly used for other databases such
        as <application>DB/2</application>.</para>

       <para> It may, however, be necessary to modify the global
       <command>ulimit</command> information in
       <filename>/etc/security/limits</filename>, as the default hard
       limits for file sizes (<varname>fsize</varname>) and numbers of
       files (<varname>nofiles</varname>) may be too low.
       </para>
      </listitem>
     </varlistentry>      

     <varlistentry>
      <term><systemitem class="osname">Solaris</></term>
      <indexterm><primary>Solaris</><secondary>IPC configuration</></>
      <listitem>
       <para>
        At least in version 2.6, the default maximum size of a shared
        memory segments is too low for <productname>PostgreSQL</>. The
        relevant settings can be changed in <filename>/etc/system</>,
        for example:
<programlisting>
set shmsys:shminfo_shmmax=0x2000000
set shmsys:shminfo_shmmin=1
set shmsys:shminfo_shmmni=256
set shmsys:shminfo_shmseg=256

set semsys:seminfo_semmap=256
set semsys:seminfo_semmni=512
set semsys:seminfo_semmns=512