From: | Andres Freund <andres(at)anarazel(dot)de> |
---|---|
To: | "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com> |
Cc: | 'Justin Pryzby' <pryzby(at)telsasoft(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: [doc fix] Correct calculation of vm.nr_hugepages |
Date: | 2018-03-01 09:54:37 |
Message-ID: | 20180301095437.shuf3hf4g6n3kchn@alap3.anarazel.de |
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Lists: | pgsql-hackers |
On 2018-02-20 02:43:32 +0000, Tsunakawa, Takayuki wrote:
> diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
> index d162acb..1aed070 100644
> --- a/doc/src/sgml/runtime.sgml
> +++ b/doc/src/sgml/runtime.sgml
> @@ -1472,14 +1472,14 @@ export PG_OOM_ADJUST_VALUE=0
> the kernel setting <varname>vm.nr_hugepages</varname>. To estimate the
> number of huge pages needed, start <productname>PostgreSQL</productname>
> without huge pages enabled and check the
> - postmaster's <varname>VmPeak</varname> value, as well as the system's
> + postmaster's anonymous shared memory segment size, as well as the system's
> huge page size, using the <filename>/proc</filename> file system. This might
> look like:
> <programlisting>
> $ <userinput>head -1 $PGDATA/postmaster.pid</userinput>
> 4170
> -$ <userinput>grep ^VmPeak /proc/4170/status</userinput>
> -VmPeak: 6490428 kB
> +$ <userinput>pmap 4170 | awk '/rw-s/ && /zero/ {print $2}'</userinput>
> +6490428K
> $ <userinput>grep ^Hugepagesize /proc/meminfo</userinput>
> Hugepagesize: 2048 kB
> </programlisting>
One disadvantage of this is that it relies on the presence of pmap,
which IIRC is not installed by default in a number of distributions. Are
we concerned about that?
Greetings,
Andres Freund
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