linux-kernel - Re: [PATCH mm-new 1/2] mm/khugepaged: optimize PTE scanning with if-else-if-else-if chain

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Message-ID: <20251003132118.qe2wipbrzwkbaatq@master>
Date: Fri, 3 Oct 2025 13:21:18 +0000
From: Wei Yang <richard.weiyang@...il.com>
To: Lance Yang <lance.yang@...ux.dev>
Cc: akpm@...ux-foundation.org, david@...hat.com, lorenzo.stoakes@...cle.com,
	ziy@...dia.com, baolin.wang@...ux.alibaba.com,
	Liam.Howlett@...cle.com, npache@...hat.com, ryan.roberts@....com,
	dev.jain@....com, baohua@...nel.org, ioworker0@...il.com,
	richard.weiyang@...il.com, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH mm-new 1/2] mm/khugepaged: optimize PTE scanning with
 if-else-if-else-if chain

On Thu, Oct 02, 2025 at 03:32:54PM +0800, Lance Yang wrote:
>From: Lance Yang <lance.yang@...ux.dev>
>
>As pointed out by Dev, the PTE checks for disjoint conditions in the
>scanning loops can be optimized. is_swap_pte, (pte_none && is_zero_pfn),
>and pte_uffd_wp are mutually exclusive.
>
>This patch refactors the loops in both __collapse_huge_page_isolate() and
>hpage_collapse_scan_pmd() to use a continuous if-else-if-else-if chain
>instead of separate if blocks.
>
>Also, this is a preparatory step to make it easier to merge the
>almost-duplicated scanning logic in these two functions, as suggested
>by David.
>
>Suggested-by: Dev Jain <dev.jain@....com>
>Suggested-by: David Hildenbrand <david@...hat.com>
>Signed-off-by: Lance Yang <lance.yang@...ux.dev>

Reviewed-by: Wei Yang <richard.weiyang@...il.com>

-- 
Wei Yang
Help you, Help me