Add mention of sysctl(8) for IPC tuning on Linux.

doc/src/sgml/runtime.sgml

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+$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.45 2000/12/30 15:03:09 petere Exp $
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 <Chapter Id="runtime">
@@ -1305,7 +1305,7 @@ env PGOPTIONS='-c geqo=off' psql
     consistently across different systems; <xref
     linkend="sysvipc-parameters"> gives an overview. The methods to
     set them, however, vary; suggestions for some platforms are given
-    below. Be aware that you will probably have to reboot your
+    below. Be warned that it is often necessary to reboot your
     machine at least, possibly even recompile the kernel, to change these
     settings.
    </para>
@@ -1596,6 +1596,22 @@ options         SEMMAP=256
         You could put these commands into a script run at boot-time.
        </para>
 
+       <para>
+        Alternatively, you can use
+        <citerefentry><refentrytitle>sysctl</refentrytitle>
+        <manvolnum>8</manvolnum></citerefentry>, if available, to
+        control these parameters.  Look for a file called
+        <filename>/etc/sysctl.conf</filename> and add lines like the
+        following to it:
+<programlisting>
+kernel.shmall = 134217728
+kernel.shmmax = 134217728
+</programlisting>
+        This file is usually processed at boot time, but
+        <application>sysctl</application> can also be called
+        explicitly later.
+       </para>
+
        <para>
         Other parameters are sufficiently sized for any application.
         If you want to see for yourself look into