From: YoungJun Park <youngjun.park@lge.com>
To: akpm@linux-foundation.org
Cc: chrisl@kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, kasong@tencent.com,
hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev,
shakeel.butt@linux.dev, muchun.song@linux.dev,
shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com,
baohua@kernel.org, gunho.lee@lge.com, taejoon.song@lge.com,
hyungjun.cho@lge.com, mkoutny@suse.com, baver.bae@lge.com,
matia.kim@lge.com
Subject: Re: [PATCH v6 3/4] mm: memcontrol: add interfaces for swap tier selection
Date: Thu, 23 Apr 2026 13:34:35 +0900 [thread overview]
Message-ID: <aemhW7/etjZUo9Xg@yjaykim-PowerEdge-T330> (raw)
In-Reply-To: <20260421055323.940344-4-youngjun.park@lge.com>
On Tue, Apr 21, 2026 at 02:53:22PM +0900, Youngjun Park wrote:
There is one review from sashiko on this 3rd patch.
https://sashiko.dev/#/patchset/20260421055323.940344-1-youngjun.park@lge.com?part=3
The concern about delegation and the global lock is valid in theory.
However, I do not think a change is necessary.
memory.swap.tiers is writable only in delegated subtrees, and delegation
itself is an administrative decision.
memory.swap.tiers is a configuration-time operation and not expected to
be updated frequently. Contention on swap_tier_lock would happen in a
configuration context (tier setup/update), not in a critical runtime
path. Therefore, it is unlikely to have a significant impact on normal
system operation.
Avoiding this would require computing the mask in the runtime path,
potentially on every I/O .Keeping the cost in the rare setup path seems preferable.
Best regards,
Youngjun Park
next prev parent reply other threads:[~2026-04-23 4:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-21 5:53 [PATCH v6 0/4] mm/swap, memcg: Introduce swap tiers for cgroup based swap control Youngjun Park
2026-04-21 5:53 ` [PATCH v6 1/4] mm: swap: introduce swap tier infrastructure Youngjun Park
2026-04-21 5:53 ` [PATCH v6 2/4] mm: swap: associate swap devices with tiers Youngjun Park
2026-04-21 5:53 ` [PATCH v6 3/4] mm: memcontrol: add interfaces for swap tier selection Youngjun Park
2026-04-23 4:34 ` YoungJun Park [this message]
2026-04-21 5:53 ` [PATCH v6 4/4] mm: swap: filter swap allocation by memcg tier mask Youngjun Park
2026-04-23 4:38 ` YoungJun Park
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