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Wed, 28 Jun 2023 00:37:21 -0700 (PDT) Received: from GL4FX4PXWL.bytedance.net ([203.208.167.146]) by smtp.gmail.com with ESMTPSA id jj6-20020a170903048600b001b8021fbcd2sm4836988plb.280.2023.06.28.00.37.18 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 28 Jun 2023 00:37:20 -0700 (PDT) From: Peng Zhang To: Liam.Howlett@oracle.com Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org, Peng Zhang Subject: [PATCH v4 4/4] maple_tree: add a fast path case in mas_wr_slot_store() Date: Wed, 28 Jun 2023 15:36:57 +0800 Message-Id: <20230628073657.75314-5-zhangpeng.00@bytedance.com> X-Mailer: git-send-email 2.37.0 (Apple Git-136) In-Reply-To: <20230628073657.75314-1-zhangpeng.00@bytedance.com> References: <20230628073657.75314-1-zhangpeng.00@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5CAF5180019 X-Stat-Signature: nwdc4egpbuymy9pgrinm9b1h6nhd36ta X-HE-Tag: 1687937842-485999 X-HE-Meta: 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 y88tuhvB nbUsLPJz/TxxnlZHblhR7prFkt7RLs4OddR5/bua3qaXNRhcoWxtWLi0hN5xTTeZrUaZ/3783HdTMj8B37DvXn8KPTArTQ6hinDfs2ffbRa/aBTg0yWnHXKLaFh+6jgUJ18WTEgDFvxnj+glg610UQf2v0ZF/4GJtrMt2j9k7aYYCPe0ljSdsn527ztKd3BnDBi/TKzYAEzxQinNQRLs+uTd6paTjkQGfimc6P1TDyJPo6cg2NMia2uXaq3p8ROFcvRcu+mQmVowUudXOVCxQ/WHcVVsXsWPM2/j4/4XAkuuyqTsTTVPM1R4yQVZBz4s7fiQqCSl0BO2ArTBuCggpyKz7NkOFEGkgjZ+mF48gejy6zWNYAttJibPIJyW5NMZJEuu5d7lCfNPS90502Sl6uR5ahIF7hh+oRiQcOnlzATXwuhUnC88rNhZSwYbnvNcjNR7lCZeSf5PcelWik5u1N3QP0iBWG3WQ7h+y 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: When expanding a range in two directions, only partially overwriting the previous and next ranges, the number of entries will not be increased, so we can just update the pivots as a fast path. However, it may introduce potential risks in RCU mode, because it updates two pivots. We only enable it in non-RCU mode. Signed-off-by: Peng Zhang Reviewed-by: Liam R. Howlett --- lib/maple_tree.c | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-) diff --git a/lib/maple_tree.c b/lib/maple_tree.c index 56b9b5be28c8..db3be8274660 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -4167,23 +4167,35 @@ static inline bool mas_wr_slot_store(struct ma_wr_state *wr_mas) { struct ma_state *mas = wr_mas->mas; unsigned char offset = mas->offset; + void __rcu **slots = wr_mas->slots; bool gap = false; - if (wr_mas->offset_end - offset != 1) - return false; - - gap |= !mt_slot_locked(mas->tree, wr_mas->slots, offset); - gap |= !mt_slot_locked(mas->tree, wr_mas->slots, offset + 1); + gap |= !mt_slot_locked(mas->tree, slots, offset); + gap |= !mt_slot_locked(mas->tree, slots, offset + 1); - if (mas->index == wr_mas->r_min) { - /* Overwriting the range and over a part of the next range. */ - rcu_assign_pointer(wr_mas->slots[offset], wr_mas->entry); - wr_mas->pivots[offset] = mas->last; - } else { - /* Overwriting a part of the range and over the next range */ - rcu_assign_pointer(wr_mas->slots[offset + 1], wr_mas->entry); + if (wr_mas->offset_end - offset == 1) { + if (mas->index == wr_mas->r_min) { + /* Overwriting the range and a part of the next one */ + rcu_assign_pointer(slots[offset], wr_mas->entry); + wr_mas->pivots[offset] = mas->last; + } else { + /* Overwriting a part of the range and the next one */ + rcu_assign_pointer(slots[offset + 1], wr_mas->entry); + wr_mas->pivots[offset] = mas->index - 1; + mas->offset++; /* Keep mas accurate. */ + } + } else if (!mt_in_rcu(mas->tree)) { + /* + * Expand the range, only partially overwriting the previous and + * next ranges + */ + gap |= !mt_slot_locked(mas->tree, slots, offset + 2); + rcu_assign_pointer(slots[offset + 1], wr_mas->entry); wr_mas->pivots[offset] = mas->index - 1; + wr_mas->pivots[offset + 1] = mas->last; mas->offset++; /* Keep mas accurate. */ + } else { + return false; } trace_ma_write(__func__, mas, 0, wr_mas->entry); -- 2.20.1