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Improvements to documentation of shared memory configuration under

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FreeBSD. From Mark Kirkwood, editorializing by Neil Conway.
This commit is contained in:
Neil Conway 2005-02-10 05:14:58 +00:00
parent 280cae35aa
commit cf1f6f98f2
1 changed files with 59 additions and 16 deletions
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75
doc/src/sgml/runtime.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.303 2005/01/23 00:30:18 momjian Exp $
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.304 2005/02/10 05:14:58 neilc Exp $
-->
<chapter Id="runtime">
@ -4351,9 +4351,55 @@ options "SEMMNS=240"
<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>$</prompt> <userinput>systcl -w kern.ipc.shmall=32768</userinput>
<prompt>$</prompt> <userinput>systcl -w kern.ipc.shmmax=134217728</userinput>
<prompt>$</prompt> <userinput>systcl -w kern.ipc.semmap=256</userinput>
</screen>
To have these settings persist over reboots, modify
<filename>/etc/sysctl.conf</filename>.
</para>
<para>
The remaining sempahore 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>
<systemitem class="osname">FreeBSD</> versions before 4.0 work like
<systemitem class="osname">NetBSD</> and <systemitem class="osname">
OpenBSD</> (see below), except that the configuration file uses the
keyword "options" instead of "option".
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><systemitem class="osname">NetBSD</></term>
<term><systemitem class="osname">OpenBSD</></term>
<indexterm><primary>FreeBSD</><secondary>IPC configuration</></>
<indexterm><primary>NetBSD</><secondary>IPC configuration</></>
<indexterm><primary>OpenBSD</><secondary>IPC configuration</></>
<listitem>
@ -4364,25 +4410,23 @@ options "SEMMNS=240"
the option <varname>SHMMAXPGS</> (in pages). The following
shows an example of how to set the various parameters:
<programlisting>
options SYSVSHM
options SHMMAXPGS=4096
options SHMSEG=256
option SYSVSHM
option SHMMAXPGS=4096
option SHMSEG=256
options SYSVSEM
options SEMMNI=256
options SEMMNS=512
options SEMMNU=256
options SEMMAP=256
option SYSVSEM
option SEMMNI=256
option SEMMNS=512
option SEMMNU=256
option SEMMAP=256
</programlisting>
(On <systemitem class="osname">NetBSD</> and <systemitem
class="osname">OpenBSD</> the key word is actually
<literal>option</literal> singular.)
</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.
Use the <command>sysctl</> setting
<literal>kern.ipc.shm_use_phys</>.
This can be accomplished using the <command>sysctl</command>
setting <literal>kern.ipc.shm_use_phys</literal>.
</para>
</listitem>
</varlistentry>
@ -4589,7 +4633,6 @@ set semsys:seminfo_semmsl=32
</varlistentry>
</variablelist>
</sect2>