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Tue, 21 Oct 2025 14:22:20 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b65eb52621csm1166878466b.59.2025.10.21.14.22.20 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 21 Oct 2025 14:22:20 -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 , wang lian Subject: [Patch v3 4/4] mm/huge_memory: optimize old_order derivation during folio splitting Date: Tue, 21 Oct 2025 21:21:42 +0000 Message-Id: <20251021212142.25766-5-richard.weiyang@gmail.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20251021212142.25766-1-richard.weiyang@gmail.com> References: <20251021212142.25766-1-richard.weiyang@gmail.com> X-Stat-Signature: g97p66a9oh9woi63dr1cw7i1t74a6ybu X-Rspamd-Queue-Id: A8302C0015 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1761081742-689719 X-HE-Meta: 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 WQJfrN/x 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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 --- mm/huge_memory.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 093b3ffb180f..a4fa8b0e5b5a 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3596,8 +3596,8 @@ static int __split_unmapped_folio(struct folio *folio, int new_order, struct address_space *mapping, bool uniform_split) { const 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 start_order = uniform_split ? new_order : old_order - 1; int split_order; folio_clear_has_hwpoisoned(folio); @@ -3609,14 +3609,11 @@ static int __split_unmapped_folio(struct folio *folio, int new_order, for (split_order = start_order; split_order >= new_order; split_order--) { - int old_order = folio_order(folio); int nr_new_folios = 1UL << (old_order - split_order); /* order-1 anonymous folio is not supported */ if (is_anon && split_order == 1) continue; - if (uniform_split && split_order != new_order) - continue; if (mapping) { /* @@ -3643,7 +3640,13 @@ static int __split_unmapped_folio(struct folio *folio, int new_order, mod_mthp_stat(old_order, MTHP_STAT_NR_ANON, -1); mod_mthp_stat(split_order, MTHP_STAT_NR_ANON, nr_new_folios); } + /* + * If uniform split, the process is complete. + * If non-uniform, continue splitting the folio at @split_at + * as long as the next @split_order is >= @new_order. + */ folio = page_folio(split_at); + old_order = split_order; } return 0; -- 2.34.1