From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7B0E6C369A1 for ; Tue, 8 Apr 2025 09:15:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=zKhG9qiEMRLJS/mGX8jO8pyM5ReATHHbxqdxWWXsPx8=; b=PBSdRKeePEHCRxmAh6Q3IMKE/L aX8idjXv2+stGw+s0tmVupi+/w9bfgiI6DiR86ndU0xRcYMV47/ow6gx1k3hvw+xHAxsc5FvJIAWJ Nl+zMqbsF2spm7lpwB3hYOwWJLkuxjqs9OsMVFPqMxUTXGBXxqvP4YV2dfTZlljDo+DTuuz14oWrh Vk0mhfj9PFtVtxgF8e77bv1gfuhCF7mvGoqU5HbBIFuu8Ja0Vq+c4FkFFcvG7MH7/qbyrnG0cV8s4 02LRXL/TaVmrkr4VxtD2m6GdPsjuZxTozYl3rTnmamIPDvxX2kbdf3O2w/SinVJahfAmZKDDnjbgp PpUb2bgg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.1 #2 (Red Hat Linux)) id 1u252i-00000003P5C-2NeW; Tue, 08 Apr 2025 09:14:52 +0000 Received: from m16.mail.163.com ([220.197.31.5]) by bombadil.infradead.org with esmtp (Exim 4.98.1 #2 (Red Hat Linux)) id 1u24nE-00000003LtW-2yVW for linux-arm-kernel@lists.infradead.org; Tue, 08 Apr 2025 08:58:54 +0000 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> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID: _____wCHF00m5fRnQGxPEw--.37725S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7Ww18ZFWxZrykJw17ZFy3twb_yoW8Xw4xpr y8CwnIqr17JFnxG393Jw1rJry5Jws3tFW7ArnIya1UJryF9rn5u34Fk34a9rWUGrZ5X3y8 Zw1UtrnruFW7CF7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0piXyCJUUUUU= X-Originating-IP: [101.132.132.191] X-CM-SenderInfo: 50dyxvpubt5qqrwthudrp/1tbiTQwpEGf03i7+0gAAs3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250408_015853_081084_C36A272D X-CRM114-Status: GOOD ( 11.76 ) 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 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, unsigned long addr, } EXPORT_SYMBOL_GPL(__contpte_try_unfold); +#define CHECK_CONTPTE_FLAG(start, ptep, orig_pte, flag) \ + do { \ + int _start = start; \ + pte_t *_ptep = ptep; \ + while (_start++ < CONT_PTES) { \ + if (pte_##flag(__ptep_get(_ptep++))) { \ + orig_pte = 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 = 0; i < CONT_PTES; i++, ptep++) { pte = __ptep_get(ptep); - if (pte_dirty(pte)) + if (pte_dirty(pte)) { orig_pte = pte_mkdirty(orig_pte); + CHECK_CONTPTE_FLAG(i, ptep, orig_pte, young); + break; + } - if (pte_young(pte)) + if (pte_young(pte)) { orig_pte = pte_mkyoung(orig_pte); + CHECK_CONTPTE_FLAG(i, ptep, orig_pte, dirty); + break; + } } return orig_pte; -- 2.34.1