linux-kernel - Re: [PATCH] mm: page_alloc: allowing mTHP compaction to capture the freed page directly

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Message-ID: <A8A8D662-478C-4A42-AB5F-C840A2DF6B55@nvidia.com>
Date: Fri, 12 Apr 2024 10:06:39 -0400
From: Zi Yan <ziy@...dia.com>
To: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: akpm@...ux-foundation.org, hannes@...xchg.org,
 mgorman@...hsingularity.net, vbabka@...e.cz, 21cnbao@...il.com,
 ryan.roberts@....com, david@...hat.com, ying.huang@...el.com,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: page_alloc: allowing mTHP compaction to capture the
 freed page directly

On 11 Apr 2024, at 23:27, Baolin Wang wrote:

> Currently, compaction_capture() does not allow lower-order allocations to
> directly capture the movable free pages, even though lower-order allocations
> might also be requesting movable pages, that can lead to more compaction
> scanning. And, with the enablement of mTHP, such situations will become more
> common.
>
> Thus allowing lower-order (mTHP) allocations of movable page types directly
> capture the movable free pages can avoid unnecessary compaction scanning,
> meanwhile that won't pollute the movable pageblock. With testing 1M mTHP
> compaction, it can be seen that compaction scanning is significantly reduced.
>
>                                    mm-unstable       patched
> Ops Compaction pages isolated      116598741.00   120946702.00
> Ops Compaction migrate scanned    1764870054.00  1488621550.00
> Ops Compaction free scanned       7707879039.00  4986299318.00
> Ops Compact scan efficiency               22.90          29.85
> Ops Compaction cost                    73797.69       72933.48
>
> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> ---
>  mm/page_alloc.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
LGTM. Thanks. Reviewed-by: Zi Yan <ziy@...dia.com>

--
Best Regards,
Yan, Zi

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