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From: =?UTF-8?Q?Roland_M=C3=BCller?= <rolmur@gmail.com>
Date: Thu, 29 Jan 2026 13:31:17 +0200
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 <CA+8p0G2TAVw7+h2s60cPe3K9=YWPWjm+sf4a_aJOb=kC-E6BDQ@mail.gmail.com>
Subject: Re: Setting huge_pages=off when HugePages are allocated in Linux?
To: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: Ron Johnson <ronljohnsonjr@gmail.com>,
 Pgsql-admin <pgsql-admin@lists.postgresql.org>
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When does it make sense to use hugepages in Postgresql?

Is usage of hugepages only available in release 18?

Laurenz Albe <laurenz.albe@cybertec.at> ezt =C3=ADrta (id=C5=91pont: 2026. =
jan. 28.,
Sze 19:02):

> On Wed, 2026-01-28 at 10:31 -0500, Ron Johnson wrote:
> > In the example in this (quite helpful) Cybertec post, 10475 HugePages
> are allocated.
> > https://www.cybertec-postgresql.com/en/huge-pages-postgresql/
> >
> > If we set "huge_pages =3D off" within PG and then restart PG, will Linu=
x
> see those 10475 HugePages as off-limits to normal 4KiB allocations?
>
> Yes.  That's why it is a good idea to set "huge_pages =3D on" if you inte=
nd
> to use them with
> PostgreSQL.  Otherwise it may happen that PostgreSQL resorts to allocatin=
g
> shared buffers
> using normal memory, and your huge pages just sit around and are wasted.
>
> Yours,
> Laurenz Albe
>
>
>

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<div dir=3D"auto">When does it make sense to use hugepages in Postgresql?=
=C2=A0<div dir=3D"auto"><br></div><div dir=3D"auto">Is usage of hugepages o=
nly available in release 18?</div></div><br><div class=3D"gmail_quote gmail=
_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">Laurenz Albe &lt;<a=
 href=3D"mailto:laurenz.albe@cybertec.at">laurenz.albe@cybertec.at</a>&gt; =
ezt =C3=ADrta (id=C5=91pont: 2026. jan. 28., Sze 19:02):<br></div><blockquo=
te class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px =
solid rgb(204,204,204);padding-left:1ex">On Wed, 2026-01-28 at 10:31 -0500,=
 Ron Johnson wrote:<br>
&gt; In the example in this (quite helpful) Cybertec post,=C2=A010475 HugeP=
ages are allocated.=C2=A0<br>
&gt; <a href=3D"https://www.cybertec-postgresql.com/en/huge-pages-postgresq=
l/" rel=3D"noreferrer noreferrer" target=3D"_blank">https://www.cybertec-po=
stgresql.com/en/huge-pages-postgresql/</a><br>
&gt; <br>
&gt; If we set &quot;huge_pages =3D off&quot; within PG and then restart PG=
, will Linux see those 10475 HugePages as off-limits to normal 4KiB allocat=
ions?<br>
<br>
Yes.=C2=A0 That&#39;s why it is a good idea to set &quot;huge_pages =3D on&=
quot; if you intend to use them with<br>
PostgreSQL.=C2=A0 Otherwise it may happen that PostgreSQL resorts to alloca=
ting shared buffers<br>
using normal memory, and your huge pages just sit around and are wasted.<br=
>
<br>
Yours,<br>
Laurenz Albe<br>
<br>
<br>
</blockquote></div>

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