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Mon, 30 Jun 2025 10:39:49 -0700 (PDT) Received: from blackdock.suse.cz ([193.86.92.181]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-453923a22fbsm100856365e9.34.2025.06.30.10.39.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Jun 2025 10:39:48 -0700 (PDT) Date: Mon, 30 Jun 2025 19:39:47 +0200 From: Michal =?utf-8?Q?Koutn=C3=BD?= To: YoungJun Park Cc: linux-mm@kvack.org, akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, shikemeng@huaweicloud.com, kasong@tencent.com, nphamcs@gmail.com, bhe@redhat.com, baohua@kernel.org, chrisl@kernel.org, muchun.song@linux.dev, iamjoonsoo.kim@lge.com, taejoon.song@lge.com, gunho.lee@lge.com Subject: Re: [RFC PATCH 1/2] mm/swap, memcg: basic structure and logic for per cgroup swap priority control Message-ID: References: <20250612103743.3385842-1-youngjun.park@lge.com> <20250612103743.3385842-2-youngjun.park@lge.com> MIME-Version: 1.0 Content-Type: multipart/signed; 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protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [RFC PATCH 1/2] mm/swap, memcg: basic structure and logic for per cgroup swap priority control MIME-Version: 1.0 On Wed, Jun 18, 2025 at 09:07:51PM +0900, YoungJun Park wrote: > This is because cgroups can still restrict swap device usage and control= =20 > device order without requiring explicit priorities for all devices. > In this view, the cgroup interface serves more as a limit or preference= =20 > mechanism across the full set of available swap devices, rather than > requiring full enumeration and configuration. I was wondering whether your use cases would be catered by having memory.swap.max limit per device (essentially disable swap to undesired device(s) for given group). The disadvantage is that memory.swap.max is already existing as scalar. Alternatively, remapping priorities to memory.swap.weight -- with sibling vs sibling competition and children treated with weight of parent when approached from the top. I find this weight semantics little weird as it'd clash with other .weight which are dual to this (cgroups compete over one device vs cgroup is choosing between multiple devices). Please try to take the existing distribution models into account not to make something overly unidiomatic, Michal --fpnjag4xaqb26ddt Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRCE24Fn/AcRjnLivR+PQLnlNv4CAUCaGLL4AAKCRB+PQLnlNv4 CI2lAP9cNd8Fw/efDHTo0CbYimuJjQR8y9PUoLFpqTT1zfv2CQEAmh2uxUSEceTY Y2x0oL70yfEQ4Y16HdkMDSN3MpuANAA= =Xz7b -----END PGP SIGNATURE----- --fpnjag4xaqb26ddt--