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Tue, 14 Oct 2025 06:49:26 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-46fab3d2c1asm153861375e9.1.2025.10.14.06.49.25 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 14 Oct 2025 06:49:25 -0700 (PDT) From: Wei Yang To: 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, lance.yang@linux.dev Cc: linux-mm@kvack.org, Wei Yang Subject: [PATCH 4/5] mm/huge_memory: Optimize old_order derivation during folio splitting Date: Tue, 14 Oct 2025 13:46:05 +0000 Message-Id: <20251014134606.22543-5-richard.weiyang@gmail.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20251014134606.22543-1-richard.weiyang@gmail.com> References: <20251014134606.22543-1-richard.weiyang@gmail.com> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: D496640002 X-Stat-Signature: 8u3pio7kwuqi98zfut54tsyzndpnqtmd X-HE-Tag: 1760449767-996605 X-HE-Meta: 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 /4thEI47 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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. * The initial @split_order (which was previously handled by a separate @start_order variable) is now directly used, and the redundant @start_order variable is removed. This change avoids unnecessary function calls and simplifies the loop setup. Signed-off-by: Wei Yang Cc: Zi Yan --- mm/huge_memory.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 482a734b61ac..63380b185df1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3528,8 +3528,7 @@ static int __split_unmapped_folio(struct folio *folio, int new_order, struct address_space *mapping, bool uniform_split) { bool is_anon = folio_test_anon(folio); - int order = folio_order(folio); - int start_order = uniform_split ? new_order : order - 1; + int old_order = folio_order(folio); int split_order; folio_clear_has_hwpoisoned(folio); @@ -3538,10 +3537,9 @@ static int __split_unmapped_folio(struct folio *folio, int new_order, * split to new_order one order at a time. For uniform split, * folio is split to new_order directly. */ - for (split_order = start_order; + for (split_order = uniform_split ? new_order : old_order - 1; split_order >= new_order; split_order--) { - int old_order = folio_order(folio); int new_folios = 1UL << (old_order - split_order); /* order-1 anonymous folio is not supported */ @@ -3576,6 +3574,7 @@ static int __split_unmapped_folio(struct folio *folio, int new_order, mod_mthp_stat(split_order, MTHP_STAT_NR_ANON, new_folios); } folio = page_folio(split_at); + old_order = split_order; } return 0; -- 2.34.1