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Fri, 03 Oct 2025 06:21:19 -0700 (PDT) Date: Fri, 3 Oct 2025 13:21:18 +0000 From: Wei Yang To: Lance Yang Cc: akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, ioworker0@gmail.com, richard.weiyang@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH mm-new 1/2] mm/khugepaged: optimize PTE scanning with if-else-if-else-if chain Message-ID: <20251003132118.qe2wipbrzwkbaatq@master> Reply-To: Wei Yang References: <20251002073255.14867-1-lance.yang@linux.dev> <20251002073255.14867-2-lance.yang@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251002073255.14867-2-lance.yang@linux.dev> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Queue-Id: 934CE20011 X-Rspamd-Server: rspam05 X-Stat-Signature: zperw4r1hxsjmxaonuur8owox74forra X-Rspam-User: X-HE-Tag: 1759497681-933809 X-HE-Meta: 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 gfoJDvwG 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Oct 02, 2025 at 03:32:54PM +0800, Lance Yang wrote: >From: Lance Yang > >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 >Suggested-by: David Hildenbrand >Signed-off-by: Lance Yang Reviewed-by: Wei Yang -- Wei Yang Help you, Help me