diff options
Diffstat (limited to 'doc/src/sgml')
| -rw-r--r-- | doc/src/sgml/runtime.sgml | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml index 9fadef5c9da..a2081c4b13a 100644 --- a/doc/src/sgml/runtime.sgml +++ b/doc/src/sgml/runtime.sgml @@ -1275,7 +1275,7 @@ sysctl -w vm.overcommit_memory=2 <para> Another approach, which can be used with or without altering <varname>vm.overcommit_memory</>, is to set the process-specific - <varname>oom_score_adj</> value for the postmaster process to + <firstterm>OOM score adjustment</> value for the postmaster process to <literal>-1000</>, thereby guaranteeing it will not be targeted by the OOM killer. The simplest way to do this is to execute <programlisting> @@ -1284,20 +1284,28 @@ echo -1000 > /proc/self/oom_score_adj 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_SCORE_ADJ=0</> added to <varname>CPPFLAGS</>. - That will cause postmaster child processes to run with the normal - <varname>oom_score_adj</> value of zero, so that the OOM killer can still - target them at need. + do this, you should also set these environment variables in the startup + script before invoking the postmaster: +<programlisting> +export PG_OOM_ADJUST_FILE=/proc/self/oom_score_adj +export PG_OOM_ADJUST_VALUE=0 +</programlisting> + These settings will cause postmaster child processes to run with the + normal OOM score adjustment of zero, so that the OOM killer can still + target them at need. You could use some other value for + <envar>PG_OOM_ADJUST_VALUE</> if you want the child processes to run + with some other OOM score adjustment. (<envar>PG_OOM_ADJUST_VALUE</> + can also be omitted, in which case it defaults to zero.) If you do not + set <envar>PG_OOM_ADJUST_FILE</>, the child processes will run with the + same OOM score adjustment as the postmaster, which is unwise since the + whole point is to ensure that the postmaster has a preferential setting. </para> <para> Older Linux kernels do not offer <filename>/proc/self/oom_score_adj</>, but may have a previous version of the same functionality called <filename>/proc/self/oom_adj</>. This works the same except the disable - value is <literal>-17</> not <literal>-1000</>. The corresponding - build flag for <productname>PostgreSQL</> is - <literal>-DLINUX_OOM_ADJ=0</>. + value is <literal>-17</> not <literal>-1000</>. </para> <note> |