From: Youngjun Park <youngjun.park@lge.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Li <chrisl@kernel.org>, Kairui Song <kasong@tencent.com>,
Kemeng Shi <shikemeng@huaweicloud.com>,
Nhat Pham <nphamcs@gmail.com>, Baoquan He <baoquan.he@linux.dev>,
Barry Song <baohua@kernel.org>,
her0gyugyu@gmail.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 0/2] mm/swap: skip empty clusters in the swapoff scan
Date: Thu, 10 Sep 2026 10:45:54 +0900 [thread overview]
Message-ID: <aqIL0nNT/RF67PIN@yjaykim-PowerEdge-T330> (raw)
In-Reply-To: <20260909104939.5203c02695fcfd7a95f4b26c@linux-foundation.org>
On Wed, Sep 09, 2026 at 10:49:39AM -0700, Andrew Morton wrote:
> On Thu, 10 Sep 2026 01:15:50 +0900 Youngjun Park <youngjun.park@lge.com> wrote:
>
> > find_next_to_unuse() walks a swap device one offset at a time. Slot
> > state now lives in a per cluster swap table, so patch 2 dismisses an
> > empty cluster with one counter read instead of SWAPFILE_CLUSTER table
> > reads.
> >
> > Patch 1 is an unrelated one line comment fix noticed on the way.
> >
> > A debug test confirmed the skip path runs, and swapoff completed
> > under load with no DEBUG_VM or lockdep splats.
>
> Please let's try to make the [0/N] words provide a summary of the
> patchset's effects. The above didn't even tell people that this is a
> swapoff optimization!
Hello Andrew.
I will keep in mind, Thank you for pointing it out.
> I asked an LLM for this summary and we came up with
>
> : Speed up swapoff and reduce scanning stalls on large, mostly empty
> : swap devices by skipping empty clusters. Reduce swapoff time on a 1
> : TiB device from 158 ms to 94 ms after filling 128 GiB, and from 392
> : ms to 73 ms after filling 512 GiB; expect little benefit when
> : substantial swap data remains.
>
> Does that sound OK?
Yes, sounds good. summary seems good enough!
Best regards,
Youngjun
prev parent reply other threads:[~2026-09-10 1:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-09 16:15 [PATCH v4 0/2] mm/swap: skip empty clusters in the swapoff scan Youngjun Park
2026-09-09 16:15 ` [PATCH v4 1/2] mm/swap: fix stale comment on swap_info_struct::cluster_info Youngjun Park
2026-09-09 16:15 ` [PATCH v4 2/2] mm/swap: scan by cluster in find_next_to_unuse() Youngjun Park
2026-09-09 18:44 ` Nhat Pham
2026-09-09 17:49 ` [PATCH v4 0/2] mm/swap: skip empty clusters in the swapoff scan Andrew Morton
2026-09-10 1:45 ` Youngjun Park [this message]
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