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From: Frédéric Yhuel <[email protected]>
To: Frits Hoogland <[email protected]>
To: Joe Conway <[email protected]>
Cc: Priya V <[email protected]>
Cc: [email protected]
Subject: Re: Safe vm.overcommit_ratio for Large Multi-Instance PostgreSQL Fleet
Date: Mon, 18 Aug 2025 18:17:50 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
	<[email protected]>
	<[email protected]>
	<[email protected]>



On 8/8/25 10:21, Frits Hoogland wrote:
> If swappiness is set to 0, but swap is available, some documentation 
> suggests it will never use anonymous memory, however I found this not to 
> be true, linux might still choose anonymous memory to reclaim.


A bug in RHEL8 meant that swappiness was not taken into account unless 
cgroupv2 was configured or vm.force_cgroup_v2_swappiness was set to 1. 
See references [1] and [2]. Could this be the cause of your observation?

[1] https://access.redhat.com/solutions/6785021
[2] https://github.com/systemd/systemd/issues/9276

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