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Mon, 07 Apr 2025 04:29:40 -0700 (PDT) Received: from EBJ9932692.tcent.cn ([43.134.231.248]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-739da0b9608sm8258637b3a.154.2025.04.07.04.29.36 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 07 Apr 2025 04:29:39 -0700 (PDT) From: Lance Yang To: xavier_qy@163.com Cc: akpm@linux-foundation.org, baohua@kernel.org, catalin.marinas@arm.com, ioworker0@gmail.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, ryan.roberts@arm.com, will@kernel.org Subject: Re: [PATCH v1] mm/contpte: Optimize loop to reduce redundant operations Date: Mon, 7 Apr 2025 19:29:22 +0800 Message-ID: <20250407112922.17766-1-ioworker0@gmail.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250407092243.2207837-1-xavier_qy@163.com> References: <20250407092243.2207837-1-xavier_qy@163.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250407_042941_446365_47A090C3 X-CRM114-Status: UNSURE ( 8.44 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Thanks for the patch. Would the following change be better? diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c index 55107d27d3f8..64eb3b2fbf06 100644 --- a/arch/arm64/mm/contpte.c +++ b/arch/arm64/mm/contpte.c @@ -174,6 +174,9 @@ pte_t contpte_ptep_get(pte_t *ptep, pte_t orig_pte) if (pte_young(pte)) orig_pte = pte_mkyoung(orig_pte); + + if (pte_young(orig_pte) && pte_dirty(orig_pte)) + break; } return orig_pte; -- We can check the orig_pte flags directly instead of using extra boolean variables, which gives us an early-exit when both dirty and young flags are set. Also, is this optimization really needed for the common case? Thanks, Lance