Message-ID: <a22c57a4b9cd72edbd210574018eeb09e3cec9df.camel@cybertec.at>
Subject: Re: Setting huge_pages=off when HugePages are allocated in Linux?
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Ron Johnson <ronljohnsonjr@gmail.com>, Pgsql-admin
	 <pgsql-admin@lists.postgresql.org>
Date: Wed, 28 Jan 2026 18:02:26 +0100
In-Reply-To: 
 <CANzqJaD0Nj2SvXrGCM-p_TUaeN84TzRteo7jxqSdARaZDiXABA@mail.gmail.com>
References: 
	<CANzqJaD0Nj2SvXrGCM-p_TUaeN84TzRteo7jxqSdARaZDiXABA@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
User-Agent: Evolution 3.58.2 (3.58.2-1.fc43) 
MIME-Version: 1.0
Archived-At: 
 <https://www.postgresql.org/message-id/a22c57a4b9cd72edbd210574018eeb09e3cec9df.camel%40cybertec.at>
Precedence: bulk

On Wed, 2026-01-28 at 10:31 -0500, Ron Johnson wrote:
> In the example in this (quite helpful) Cybertec post,=C2=A010475 HugePage=
s are allocated.=C2=A0
> https://www.cybertec-postgresql.com/en/huge-pages-postgresql/
>=20
> If we set "huge_pages =3D off" within PG and then restart PG, will Linux =
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 intend=
 to use them with
PostgreSQL.  Otherwise it may happen that PostgreSQL resorts to allocating =
shared buffers
using normal memory, and your huge pages just sit around and are wasted.

Yours,
Laurenz Albe