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Wed, 22 Oct 2025 18:32:50 -0700 (PDT) From: wang lian To: richard.weiyang@gmail.com Cc: Liam.Howlett@oracle.com, akpm@linux-foundation.org, baohua@kernel.org, baolin.wang@linux.alibaba.com, david@redhat.com, dev.jain@arm.com, lance.yang@linux.dev, lianux.mm@gmail.com, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, npache@redhat.com, ryan.roberts@arm.com, ziy@nvidia.com Subject: Re: [Patch v3 4/4] mm/huge_memory: optimize old_order derivation during folio splitting Date: Thu, 23 Oct 2025 09:32:36 +0800 Message-ID: <20251023013236.16142-1-lianux.mm@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20251021212142.25766-5-richard.weiyang@gmail.com> References: <20251021212142.25766-5-richard.weiyang@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam01 X-Stat-Signature: zf7kt9choyf5um14d4yhw98sffcz3qmj X-Rspam-User: X-Rspamd-Queue-Id: 61E1C20008 X-HE-Tag: 1761183172-995065 X-HE-Meta: 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 3WtNgMaD 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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: > Folio splitting requires both the folio's original order (@old_order) > and the new target order (@split_order). > In the current implementation, @old_order is repeatedly retrieved using > folio_order(). > However, for every iteration after the first, the folio being split is > the result of the previous split, meaning its order is already known to > be equal to the previous iteration's @split_order. > This commit optimizes the logic: > * Instead of calling folio_order(), we now set @old_order directly to > the value of @split_order from the previous iteration. > This change avoids unnecessary function calls and simplifies the loop > setup. > Also it removes a check for non-existent case, since for uniform > splitting we only do split when @split_order == @new_order. > Signed-off-by: Wei Yang > Cc: Zi Yan > Cc: wang lian --- LGTM. Reviewed-by: wang lian -- Best Regards, wang lian