diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/runtime.sgml | 35 |
1 files changed, 28 insertions, 7 deletions
diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml index a68ba64dac5..6213b925307 100644 --- a/doc/src/sgml/runtime.sgml +++ b/doc/src/sgml/runtime.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.429 2009/12/10 06:32:28 petere Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.430 2010/01/11 18:39:32 tgl Exp $ --> <chapter Id="runtime"> <title>Server Setup and Operation</title> @@ -1244,7 +1244,7 @@ default:\ this (consult your system documentation and configuration on where to look for such a message): <programlisting> -Out of Memory: Killed process 12345 (postgres). +Out of Memory: Killed process 12345 (postgres). </programlisting> This indicates that the <filename>postgres</filename> process has been terminated due to memory pressure. @@ -1258,13 +1258,13 @@ Out of Memory: Killed process 12345 (postgres). <productname>PostgreSQL</productname> on a machine where you can be sure that other processes will not run the machine out of memory. If memory is tight, increasing the swap space of the - operating system can help avoiding the problem, because the - out-of-memory (OOM) killer is invoked whenever physical memory and + operating system can help avoid the problem, because the + out-of-memory (OOM) killer is invoked only when physical memory and swap space are exhausted. </para> <para> - On Linux 2.6 and later, an additional measure is to modify the + On Linux 2.6 and later, it is possible to modify the kernel's behavior so that it will not <quote>overcommit</> memory. Although this setting will not prevent the <ulink url="http://lwn.net/Articles/104179/">OOM killer</> from being invoked @@ -1275,12 +1275,32 @@ Out of Memory: Killed process 12345 (postgres). sysctl -w vm.overcommit_memory=2 </programlisting> or placing an equivalent entry in <filename>/etc/sysctl.conf</>. - You might also wish to modify the related setting - <literal>vm.overcommit_ratio</>. For details see the kernel documentation + You might also wish to modify the related setting + <varname>vm.overcommit_ratio</>. For details see the kernel documentation file <filename>Documentation/vm/overcommit-accounting</>. </para> <para> + Another approach, which can be used with or without altering + <varname>vm.overcommit_memory</>, is to set the process-specific + <varname>oom_adj</> value for the postmaster process to <literal>-17</>, + thereby guaranteeing it will not be targeted by the OOM killer. The + simplest way to do this is to execute +<programlisting> +echo -17 > /proc/self/oom_adj +</programlisting> + in the postmaster's startup script just before invoking the postmaster. + Note that this action must be done as root, or it will have no effect; + so a root-owned startup script is the easiest place to do it. If you + do this, you may also wish to build <productname>PostgreSQL</> + with <literal>-DLINUX_OOM_ADJ=0</> added to <varname>CFLAGS</>. + That will cause postmaster child processes to run with the normal + <varname>oom_adj</> value of zero, so that the OOM killer can still + target them at need. + </para> + + <note> + <para> Some vendors' Linux 2.4 kernels are reported to have early versions of the 2.6 overcommit <command>sysctl</command> parameter. However, setting <literal>vm.overcommit_memory</> to 2 @@ -1294,6 +1314,7 @@ sysctl -w vm.overcommit_memory=2 feature is there. If in any doubt, consult a kernel expert or your kernel vendor. </para> + </note> </sect2> </sect1> |