From nobody Fri Dec 19 14:28:27 2025 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.2]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0D28C33CA for ; Tue, 8 Apr 2025 08:59:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.2 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744102743; cv=none; b=VaHYxv1kdzjlkSje/j/KVG+w9Xbs/noKwROTLqKLunFX9xv/ar7nOf40kqtwmvj/o7jNYzIGCsjusUQyw4Z/uBdNt12P/0OywX/exZVc9NdrogVEolt2msemaBc3Nkycp+Oqubwq7snPbwOF/3rT2mtAiU0C8Ev28vIHzHURuqw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744102743; c=relaxed/simple; bh=72jwfitser1aQb9gjC6pY+/0SixGdsnc79rvI3BbmAk=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=q2ro/kJZGSFdAXFeo27RAi9iG6yqGfGKhONDU0jpWZ97jFJkWTzHNxdnOwfj6I7BDCFRJ9ueZak2kWtjC2RNDduGYHXBHhOi0ggZ0l/7IcuQFGXLdpA1Wamu4gIcXQXrI/Avl8xq6loy5vuV8hZ8pbVZovRfSJ1A8lX8/FZIcLI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=DZ5qJ+c0; arc=none smtp.client-ip=220.197.31.2 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="DZ5qJ+c0" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id:MIME-Version; bh=zKhG9 qiEMRLJS/mGX8jO8pyM5ReATHHbxqdxWWXsPx8=; b=DZ5qJ+c0PnOUua2pWcX9w MAkfLRn2tolNjzPPBDRwOJ/120UmLBKlssIdgsWiCq1umm/otz5XdwNI/7UuOqk+ vo7XJPCRlnBwwkRmiUkM3XWUhfPqmuHgXBSpc4W5uJ3P5SxJboDpkQmPLNr8xsmA xl/yBB/UfBP2cuGTFh5E0g= Received: from localhost (unknown []) by gzga-smtp-mtada-g1-4 (Coremail) with SMTP id _____wCHF00m5fRnQGxPEw--.37725S2; Tue, 08 Apr 2025 16:58:14 +0800 (CST) From: Xavier To: dev.jain@arm.com, akpm@linux-foundation.org, baohua@kernel.org, ryan.roberts@arm.com, catalin.marinas@arm.com, ioworker0@gmail.com Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, will@kernel.org, xavier_qy@163.com Subject: [PATCH v2 1/1] mm/contpte: Optimize loop to reduce redundant operations Date: Tue, 8 Apr 2025 16:58:09 +0800 Message-Id: <20250408085809.2217618-2-xavier_qy@163.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250408085809.2217618-1-xavier_qy@163.com> References: <027cc666-a562-46fa-bca5-1122ea00ec0e@arm.com> <20250408085809.2217618-1-xavier_qy@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _____wCHF00m5fRnQGxPEw--.37725S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7Ww18ZFWxZrykJw17ZFy3twb_yoW8Xw4xpr y8CwnIqr17JFnxG393Jw1rJry5Jws3tFW7ArnIya1UJryF9rn5u34Fk34a9rWUGrZ5X3y8 Zw1UtrnruFW7CF7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0piXyCJUUUUU= X-CM-SenderInfo: 50dyxvpubt5qqrwthudrp/1tbiTQwpEGf03i7+0gAAs3 Content-Type: text/plain; charset="utf-8" This commit optimizes the contpte_ptep_get function by adding early termination logic. It checks if the dirty and young bits of orig_pte are already set and skips redundant bit-setting operations during the loop. This reduces unnecessary iterations and improves performance. Signed-off-by: Xavier --- arch/arm64/mm/contpte.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c index bcac4f55f9c1..034d153d7d19 100644 --- a/arch/arm64/mm/contpte.c +++ b/arch/arm64/mm/contpte.c @@ -152,6 +152,18 @@ void __contpte_try_unfold(struct mm_struct *mm, unsign= ed long addr, } EXPORT_SYMBOL_GPL(__contpte_try_unfold); =20 +#define CHECK_CONTPTE_FLAG(start, ptep, orig_pte, flag) \ + do { \ + int _start =3D start; \ + pte_t *_ptep =3D ptep; \ + while (_start++ < CONT_PTES) { \ + if (pte_##flag(__ptep_get(_ptep++))) { \ + orig_pte =3D pte_mk##flag(orig_pte); \ + break; \ + } \ + } \ + } while (0) + pte_t contpte_ptep_get(pte_t *ptep, pte_t orig_pte) { /* @@ -169,11 +181,17 @@ pte_t contpte_ptep_get(pte_t *ptep, pte_t orig_pte) for (i =3D 0; i < CONT_PTES; i++, ptep++) { pte =3D __ptep_get(ptep); =20 - if (pte_dirty(pte)) + if (pte_dirty(pte)) { orig_pte =3D pte_mkdirty(orig_pte); + CHECK_CONTPTE_FLAG(i, ptep, orig_pte, young); + break; + } =20 - if (pte_young(pte)) + if (pte_young(pte)) { orig_pte =3D pte_mkyoung(orig_pte); + CHECK_CONTPTE_FLAG(i, ptep, orig_pte, dirty); + break; + } } =20 return orig_pte; --=20 2.34.1