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* RHEL-8 Kernel Settings
@ 2021-06-10 18:06 John Wiencek <jwiencek3@comcast.net>
2021-06-11 06:56 ` Re: RHEL-8 Kernel Settings Laurenz Albe <laurenz.albe@cybertec.at>
0 siblings, 1 reply; 5+ messages in thread
From: John Wiencek @ 2021-06-10 18:06 UTC (permalink / raw)
To: Pgsql-admin <pgsql-admin@lists.postgresql.org>
Hello
I’m looking for assistance in determining kernel setting for a VM RHEL-8 linux server running postgresql-13.
I have 3 server groupings
1) 2 vcpu’s 8gb memory
2) 4 cpu’s 16gb memory
3) 8 cpu’s 32gb memory
I’ve read various articles and the PostgreSQL documentation . Does anyone have practical experiences doing this kind of set up
Do kernel setting requirements change based on the number of cpu’s and amount of memory? I’ve not read any mention of this.
Regards
John W
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: RHEL-8 Kernel Settings
2021-06-10 18:06 RHEL-8 Kernel Settings John Wiencek <jwiencek3@comcast.net>
@ 2021-06-11 06:56 ` Laurenz Albe <laurenz.albe@cybertec.at>
2021-06-11 07:06 ` Re: RHEL-8 Kernel Settings Johannes Truschnigg <johannes@truschnigg.info>
2021-06-11 09:07 ` Re: RHEL-8 Kernel Settings Jwiencek3 <jwiencek3@comcast.net>
0 siblings, 2 replies; 5+ messages in thread
From: Laurenz Albe @ 2021-06-11 06:56 UTC (permalink / raw)
To: John Wiencek <jwiencek3@comcast.net>; Pgsql-admin <pgsql-admin@lists.postgresql.org>
On Thu, 2021-06-10 at 13:06 -0500, John Wiencek wrote:
> I’m looking for assistance in determining kernel setting for a VM RHEL-8 linux server running postgresql-13.
>
> I have 3 server groupings
>
> 1) 2 vcpu’s 8gb memory
> 2) 4 cpu’s 16gb memory
> 3) 8 cpu’s 32gb memory
>
> I’ve read various articles and the PostgreSQL documentation . Does anyone have practical experiences doing this kind of set up
>
> Do kernel setting requirements change based on the number of cpu’s and amount of memory? I’ve not read any mention of this.
I recommend setting
vm.overcommit_memory = 2
vm.overcommit_ratio (the correct value depends on your swap)
vm.swappiness = 0
Also, disable Transparent Hugepages.
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: RHEL-8 Kernel Settings
2021-06-10 18:06 RHEL-8 Kernel Settings John Wiencek <jwiencek3@comcast.net>
2021-06-11 06:56 ` Re: RHEL-8 Kernel Settings Laurenz Albe <laurenz.albe@cybertec.at>
@ 2021-06-11 07:06 ` Johannes Truschnigg <johannes@truschnigg.info>
2021-06-11 07:12 ` Re: RHEL-8 Kernel Settings Laurenz Albe <laurenz.albe@cybertec.at>
1 sibling, 1 reply; 5+ messages in thread
From: Johannes Truschnigg @ 2021-06-11 07:06 UTC (permalink / raw)
To: pgsql-admin@lists.postgresql.org
On Fri, Jun 11, 2021 at 08:56:13AM +0200, Laurenz Albe wrote:
> [...]
> I recommend setting
>
> vm.overcommit_memory = 2
Be careful with this though, most applications no not allocate memory as
thoughtfully as Postgres - so if your server is running any other kind of
service/software in addition to Postgres, you should make sure that can
survive Linux not overcommitting like there's no tomorrow, too.
--
with best regards:
- Johannes Truschnigg ( johannes@truschnigg.info )
www: https://johannes.truschnigg.info/
phone: +43 650 2 133337
xmpp: johannes@truschnigg.info
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^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: RHEL-8 Kernel Settings
2021-06-10 18:06 RHEL-8 Kernel Settings John Wiencek <jwiencek3@comcast.net>
2021-06-11 06:56 ` Re: RHEL-8 Kernel Settings Laurenz Albe <laurenz.albe@cybertec.at>
2021-06-11 07:06 ` Re: RHEL-8 Kernel Settings Johannes Truschnigg <johannes@truschnigg.info>
@ 2021-06-11 07:12 ` Laurenz Albe <laurenz.albe@cybertec.at>
0 siblings, 0 replies; 5+ messages in thread
From: Laurenz Albe @ 2021-06-11 07:12 UTC (permalink / raw)
To: Johannes Truschnigg <johannes@truschnigg.info>; pgsql-admin@lists.postgresql.org
On Fri, 2021-06-11 at 09:06 +0200, Johannes Truschnigg wrote:
> On Fri, Jun 11, 2021 at 08:56:13AM +0200, Laurenz Albe wrote:
> > [...]
> > I recommend setting
> >
> > vm.overcommit_memory = 2
>
> Be careful with this though, most applications no not allocate memory as
> thoughtfully as Postgres - so if your server is running any other kind of
> service/software in addition to Postgres, you should make sure that can
> survive Linux not overcommitting like there's no tomorrow, too.
On the contrary: if there is some software that allocates memory like crazy,
you want to disable overcommit, so that you get a nice OOM error rather
than killed processes, which result in PostgreSQL going through crash
recovery.
But I think that running such a misbehaving program on a database
machine is a bad idea.
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: RHEL-8 Kernel Settings
2021-06-10 18:06 RHEL-8 Kernel Settings John Wiencek <jwiencek3@comcast.net>
2021-06-11 06:56 ` Re: RHEL-8 Kernel Settings Laurenz Albe <laurenz.albe@cybertec.at>
@ 2021-06-11 09:07 ` Jwiencek3 <jwiencek3@comcast.net>
1 sibling, 0 replies; 5+ messages in thread
From: Jwiencek3 @ 2021-06-11 09:07 UTC (permalink / raw)
To: Laurenz Albe <laurenz.albe@cybertec.at>; +Cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
Other than HugePages are any other settings determined by the amount of memory on a server?
John
Sent from my iPad
> On Jun 11, 2021, at 1:56 AM, Laurenz Albe <laurenz.albe@cybertec.at> wrote:
>
> On Thu, 2021-06-10 at 13:06 -0500, John Wiencek wrote:
>> I’m looking for assistance in determining kernel setting for a VM RHEL-8 linux server running postgresql-13.
>>
>> I have 3 server groupings
>>
>> 1) 2 vcpu’s 8gb memory
>> 2) 4 cpu’s 16gb memory
>> 3) 8 cpu’s 32gb memory
>>
>> I’ve read various articles and the PostgreSQL documentation . Does anyone have practical experiences doing this kind of set up
>>
>> Do kernel setting requirements change based on the number of cpu’s and amount of memory? I’ve not read any mention of this.
>
> I recommend setting
>
> vm.overcommit_memory = 2
> vm.overcommit_ratio (the correct value depends on your swap)
> vm.swappiness = 0
>
> Also, disable Transparent Hugepages.
>
> Yours,
> Laurenz Albe
> --
> Cybertec | https://www.cybertec-postgresql.com
>
^ permalink raw reply [nested|flat] 5+ messages in thread
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-- links below jump to the message on this page --
2021-06-10 18:06 RHEL-8 Kernel Settings John Wiencek <jwiencek3@comcast.net>
2021-06-11 06:56 ` Laurenz Albe <laurenz.albe@cybertec.at>
2021-06-11 07:06 ` Johannes Truschnigg <johannes@truschnigg.info>
2021-06-11 07:12 ` Laurenz Albe <laurenz.albe@cybertec.at>
2021-06-11 09:07 ` Jwiencek3 <jwiencek3@comcast.net>
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