From: Johannes Weiner <hannes@cmpxchg.org>
To: Youngjun Park <youngjun.park@lge.com>
Cc: akpm@linux-foundation.org, chrisl@kernel.org, linux-mm@kvack.org,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
kasong@tencent.com, mhocko@kernel.org, roman.gushchin@linux.dev,
shakeel.butt@linux.dev, muchun.song@linux.dev,
shikemeng@huaweicloud.com, baoquan.he@linux.dev,
baohua@kernel.org, yosry@kernel.org, joshua.hahnjy@gmail.com,
taejoon.song@lge.com, her0gyugyu@gmail.com, lianux.mm@gmail.com
Subject: Re: [RFC PATCH v11 0/4] mm/swap: priority-based swap tiers with per-cgroup selection
Date: Wed, 16 Sep 2026 16:04:34 -0400 [thread overview]
Message-ID: <20260916200434.GA5784@cmpxchg.org> (raw)
In-Reply-To: <20260916183437.2946306-1-youngjun.park@lge.com>
On Thu, Sep 17, 2026 at 03:34:33AM +0900, Youngjun Park wrote:
> Per-cgroup swap in debugfs
> ==========================
>
> Patches 3 and 4 let a memory cgroup choose its tiers through debugfs.
>
> # swapon -p 100 /dev/nvme0n1p2
> # swapon -p 50 /dev/sdb2
> # cat /sys/kernel/debug/swap/tiers
> Idx Prio
> 0 100
> 1 50
> # echo "/batch 0x2" > /sys/kernel/debug/swap/memcg_tiers
>
> Bit i of the mask is tier i, so /batch swaps only to sdb2. A tier keeps
> its index for its lifetime, so the mask keeps selecting the same tier
> across swapon and swapoff.
Can the cgroup be given a priority limit? That would have pretty
obvious inheritance semantics:
root
`- batch (memory.swap.prio.max = 20)
`- task (memory.swap.prio.max = max)
`- logs (memory.swap.prio.max = 10)
`- interactive (memory.swap.prio.max = max)
`- task (memory.swap.prio.max)
prev parent reply other threads:[~2026-09-16 20:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-16 18:34 Youngjun Park
2026-09-16 18:34 ` [RFC PATCH v11 1/4] mm: swap: introduce swap tier infrastructure Youngjun Park
2026-09-16 18:34 ` [RFC PATCH v11 2/4] mm: swap: allocate swap slots from swap tiers Youngjun Park
2026-09-16 18:34 ` [RFC PATCH v11 3/4] mm: swap: add a debugfs interface for memcg tier selection Youngjun Park
2026-09-16 18:34 ` [RFC PATCH v11 4/4] mm: swap: filter swap allocation by memcg tier mask Youngjun Park
2026-09-16 20:04 ` Johannes Weiner [this message]
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