From: Shakeel Butt <shakeel.butt@linux.dev>
To: Kairui Song <ryncsn@gmail.com>
Cc: cgroups@vger.kernel.org, linux-mm@kvack.org,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, Kairui Song <kasong@tencent.com>
Subject: Re: [PATCH] memcg: consolidate private id refcount get/put helpers
Date: Fri, 13 Feb 2026 21:55:38 -0800 [thread overview]
Message-ID: <CAGj-7pURg5F_2zMAWseutKTKoAdzn=8fsNSqUsoNCWyurbFyGw@mail.gmail.com> (raw)
In-Reply-To: <20260213-memcg-privid-v1-1-d8cb7afcf831@tencent.com>
On Fri, Feb 13, 2026 at 2:03 AM Kairui Song <ryncsn@gmail.com> wrote:
>
> From: Kairui Song <kasong@tencent.com>
>
> We currently have two different sets of helpers for getting or putting
> the private IDs' refcount for order 0 and large folios. This is
> redundant. Just use one and always acquire the refcount of the swapout
> folio size unless it's zero, and put the refcount using the folio size
> if the charge failed, since the folio size can't change. Then there is
> no need to update the refcount for tail pages.
>
> Same for freeing, then only one pair of get/put helper is needed now.
>
> The performance might be slightly better, too: both "inc unless zero"
> and "add unless zero" use the same cmpxchg implementation. For large
> folios, we saved an atomic operation. And for both order 0 and large
> folios, we saved a branch.
>
> Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Shakeel Butt <shakeel.butt@gmail.com>
prev parent reply other threads:[~2026-02-14 5:55 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-13 10:03 Kairui Song
2026-02-13 20:08 ` Johannes Weiner
2026-02-14 0:56 ` Chen Ridong
2026-02-14 5:55 ` Shakeel Butt [this message]
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