database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-30 11:03:19 +03:00
Code Activity

Support Linux's oom_score_adj API as well as the older oom_adj API.

Browse Source 
The simplest way to handle this is just to copy-and-paste the relevant
code block in fork_process.c, so that's what I did. (It's possible that
something more complicated would be useful to packagers who want to work
with either the old or the new API; but at this point the number of such
people is rapidly approaching zero, so let's just get the minimal thing
done.)  Update relevant documentation as well.
This commit is contained in:
Tom Lane
2012-06-13 15:34:57 -04:00
parent b9212e379c
commit 93f4d7f806
3 changed files with 59 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
doc/src/sgml/runtime.sgml
View File

@ -1268,7 +1268,7 @@ default:\
In Linux 2.4 and later, the default virtual memory behavior is not
optimal for <productname>PostgreSQL</productname>. Because of the
way that the kernel implements memory overcommit, the kernel might
terminate the <productname>PostgreSQL</productname> server (the
terminate the <productname>PostgreSQL</productname> postmaster (the
master server process) if the memory demands of
another process cause the system to run out of virtual memory.
</para>
@ -1317,22 +1317,31 @@ 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_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
<varname>oom_score_adj</> 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>
echo -17 > /proc/self/oom_adj
echo -1000 > /proc/self/oom_score_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>CPPFLAGS</>.
with <literal>-DLINUX_OOM_SCORE_ADJ=0</> added to <varname>CPPFLAGS</>.
That will cause postmaster child processes to run with the normal
<varname>oom_adj</> value of zero, so that the OOM killer can still
<varname>oom_score_adj</> value of zero, so that the OOM killer can still
target them at need.
</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</>.
</para>
<note>
<para>
Some vendors' Linux 2.4 kernels are reported to have early versions