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From: Laurenz Albe <[email protected]>
To: Ron Johnson <[email protected]>
To: Pgsql-admin <[email protected]>
Subject: Re: Setting huge_pages=off when HugePages are allocated in Linux?
Date: Wed, 28 Jan 2026 18:02:26 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <CANzqJaD0Nj2SvXrGCM-p_TUaeN84TzRteo7jxqSdARaZDiXABA@mail.gmail.com>
References: <CANzqJaD0Nj2SvXrGCM-p_TUaeN84TzRteo7jxqSdARaZDiXABA@mail.gmail.com>

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 = 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 = 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

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