Move "maxusers n" from the kernel configuration chapter to the tuning
kernel limits chapter. Suggested by: blackend (some time ago) Approved by: brueffer (mentor)
This commit is contained in:
Joel Dahl
parent
150cec30e4
commit
0fe6859cda
Notes:
svn2git
2020-12-08 03:00:23 +00:00
svn path=/head/; revision=25446
2 changed files with 44 additions and 59 deletions
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@ -2046,9 +2046,9 @@ device_probe_and_attach: cbb0 attach returned 12</screen>
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kind and number of services running concurrently.</para>
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<para><varname>kern.maxfile</varname>'s default value is
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dictated by the <option>MAXUSERS</option> option in your
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dictated by the <option>maxusers</option> option in your
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kernel configuration file. <varname>kern.maxfiles</varname> grows
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proportionally to the value of <option>MAXUSERS</option>. When
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proportionally to the value of <option>maxusers</option>. When
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compiling a custom kernel, it is a good idea to set this kernel
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configuration option according to the uses of your system. From
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this number, the kernel is given most of its pre-defined limits.
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@ -2056,10 +2056,48 @@ device_probe_and_attach: cbb0 attach returned 12</screen>
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connected at once, the resources needed may be similar to a
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high-scale web server.</para>
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<note><para>As of &os; 4.5, setting <option>MAXUSERS</option> to
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<literal>0</literal> in your kernel configuration file will choose
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a reasonable default value based on the amount of RAM present in
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your system.</para></note>
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<para>Starting with &os; 4.5, the system will auto-tune
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<literal>maxusers</literal> for you if you explicitly set it to
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<literal>0</literal><footnote>
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<para>The auto-tuning algorithm sets
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<literal>maxusers</literal> equal to the amount of memory in the
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system, with a minimum of 32, and a maximum of 384.</para>
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</footnote>. In &os; 5.X and above, <literal>maxusers</literal>
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will default to <literal>0</literal> if not specified. If you
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are using an version of &os; earlier than 4.5, or you want to
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manage it yourself you will want to set
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<literal>maxusers</literal> to at least 4, especially if you are
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using the X Window System or compiling software. The reason is that
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the most important table set by <literal>maxusers</literal> is the
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maximum number of processes, which is set to <literal>20 + 16 *
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maxusers</literal>, so if you set <literal>maxusers</literal> to 1,
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then you can only have 36 simultaneous processes, including the 18
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or so that the system starts up at boot time and the 15 or so you
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will probably create when you start the X Window System. Even a
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simple task like reading a manual page will start up nine
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processes to filter, decompress, and view it. Setting
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<literal>maxusers</literal> to 64 will allow you to have up to 1044
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simultaneous processes, which should be enough for nearly all uses.
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If, however, you see the dreaded <errortype>proc table
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full</errortype> error when trying to start another program, or are
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running a server with a large number of simultaneous users (like
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<hostid role="fqdn">ftp.FreeBSD.org</hostid>), you can always
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increase the number and rebuild.</para>
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<note>
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<para><literal>maxusers</literal> does <emphasis>not</emphasis>
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limit the number of users which can log into your machine. It
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simply sets various table sizes to reasonable values considering
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the maximum number of users you will likely have on your system
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and how many processes each of them will be running. One keyword
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which <emphasis>does</emphasis> limit the number of simultaneous
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remote logins and X terminal windows is <link
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linkend="kernelconfig-ptys"><literal>pseudo-device pty
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16</literal></link>. With &os; 5.X, you do not have to
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worry about this number since the &man.pty.4; driver is
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<quote>auto-cloning</quote>; you simply use the line
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<literal>device pty</literal> in your configuration file.</para>
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</note>
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</sect3>
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@ -601,59 +601,6 @@ cpu I686_CPU</programlisting>
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kernel, so it is useful to give the new kernel a different name if you
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want to keep it separate from your usual kernel (e.g., you want to
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build an experimental kernel).</para>
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<indexterm>
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<primary>kernel options</primary>
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<secondary>maxusers</secondary>
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</indexterm>
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<programlisting>maxusers <replaceable>n</replaceable></programlisting>
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<para>The <literal>maxusers</literal> option sets the size of a number
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of important system tables. This number is supposed to be roughly
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equal to the number of simultaneous users you expect to have on your
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machine.</para>
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<para>Starting with &os; 4.5, the system will auto-tune this setting
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for you if you explicitly set it to <literal>0</literal><footnote>
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<para>The auto-tuning algorithm sets <literal>maxusers</literal> equal
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to the amount of memory in the system, with a minimum of 32, and a
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maximum of 384.</para></footnote>.
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In &os; 5.X and above, <literal>maxusers</literal> will default to
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<literal>0</literal> if not specified. If you are using an
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version of &os; earlier than 4.5, or you want to manage it
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yourself you will want to set
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<literal>maxusers</literal> to at least 4, especially if you are
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using the X Window System or compiling software. The reason is that
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the most important table set by <literal>maxusers</literal> is the
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maximum number of processes, which is set to <literal>20 + 16 *
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maxusers</literal>, so if you set <literal>maxusers</literal> to 1,
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then you can only have 36 simultaneous processes, including the 18
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or so that the system starts up at boot time and the 15 or so you
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will probably create when you start the X Window System. Even a
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simple task like reading a manual page will start up nine processes to
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filter, decompress, and view it. Setting
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<literal>maxusers</literal> to 64 will allow you to have up to 1044
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simultaneous processes, which should be enough for nearly all uses.
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If, however, you see the dreaded <errortype>proc table
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full</errortype> error when trying to start another program, or are
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running a server with a large number of simultaneous users (like
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<hostid role="fqdn">ftp.FreeBSD.org</hostid>), you can always
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increase the number and rebuild.</para>
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<note>
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<para><literal>maxusers</literal> does <emphasis>not</emphasis>
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limit the number of users which can log into your machine. It
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simply sets various table sizes to reasonable values considering
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the maximum number of users you will likely have on your system
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and how many processes each of them will be running. One keyword
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which <emphasis>does</emphasis> limit the number of simultaneous
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remote logins and X terminal windows is <link
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linkend="kernelconfig-ptys"><literal>pseudo-device pty
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16</literal></link>. With &os; 5.X, you do not have to
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worry about this number since the &man.pty.4; driver is
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<quote>auto-cloning</quote>; you simply use the line
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<literal>device pty</literal> in your configuration file.</para>
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</note>
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<programlisting># Floating point support - do not disable.
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device npx</programlisting>
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