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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF768D2F7F0 for ; Thu, 17 Oct 2024 06:18:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 500606B007B; Thu, 17 Oct 2024 02:18:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4B09A6B0082; Thu, 17 Oct 2024 02:18:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 378B96B0083; Thu, 17 Oct 2024 02:18:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 1440C6B007B for ; Thu, 17 Oct 2024 02:18:53 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 783E9AC5BB for ; Thu, 17 Oct 2024 06:18:31 +0000 (UTC) X-FDA: 82682090358.20.5F1475E Received: from mail-oa1-f46.google.com (mail-oa1-f46.google.com [209.85.160.46]) by imf03.hostedemail.com (Postfix) with ESMTP id 7F27520003 for ; Thu, 17 Oct 2024 06:18:45 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=bytedance.com header.s=google header.b=aiNoFY+i; dmarc=pass (policy=quarantine) header.from=bytedance.com; spf=pass (imf03.hostedemail.com: domain of lizhe.67@bytedance.com designates 209.85.160.46 as permitted sender) smtp.mailfrom=lizhe.67@bytedance.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1729145883; a=rsa-sha256; cv=none; b=bVYn6Lv8eTMJk8zpQtoUZf+OcpK6sqVsuS5A5TncCYd4ZcsYEydOl2AGlqcxaACTvYSdtI AxphWoOQiGRA41kr477Y96s2/kcDdJ/GuPgo8zLOh/5/Dm/XzZFTjr24ZeitW4Pk/0Vtlg kwOnvO9uh+lwn5gUSbfg1hpHJCc4RWI= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=bytedance.com header.s=google header.b=aiNoFY+i; dmarc=pass (policy=quarantine) header.from=bytedance.com; spf=pass (imf03.hostedemail.com: domain of lizhe.67@bytedance.com designates 209.85.160.46 as permitted sender) smtp.mailfrom=lizhe.67@bytedance.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1729145883; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=7AMuJ7HqPV1JOGCg5tobowAHNkSY7nMnl7ipVjQvkNU=; b=vJPQKEFoZohJV1KmKnMCjJvni+TdsVhAtAHYhcnfMy6ckrS42sb2OEKIab0JWGD4fycdmu nm5Fj6r+6xFcRFAXNBT+J/3i8cfQyeFdTQNb2ep0QXcwMc759faIGwpkBVyFC5VNkMLrDj W99Rvg663UY7DkYUABk31j9/HXXiDpc= Received: by mail-oa1-f46.google.com with SMTP id 586e51a60fabf-2890f273296so221135fac.2 for ; Wed, 16 Oct 2024 23:18:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1729145929; x=1729750729; darn=kvack.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=7AMuJ7HqPV1JOGCg5tobowAHNkSY7nMnl7ipVjQvkNU=; b=aiNoFY+iG7fditpxM3yOtSQU1jRt5jvHVTvJGrvoNqOzTd/pTdjRHsxno2CLqkpOoc YkGYE/U7JqJikLs5clCKvGdKhxOt1Shj4l/QjLxDAdoJC8UZztAfAekiE+mPhSjuAuL1 dcw1Sx8vjOPuvxT9AbubbpuhzOzL+s/4YnENbeKuCsF/kZJK1ENYfvFul1Vx8qVM+HnV 8Ds4iaD+RCD6ZD/uRauO+pGCLU2rqpNsHpU8yI7C6XrmCTPC6V6xgJvzDUeceEY9XP8V EgnS32UyLZGw4qb6X73rlxkZMgjOiV73hCjUs/arhkWsWifFz4ipxiOBrrimYUgenHsX FO7A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729145929; x=1729750729; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=7AMuJ7HqPV1JOGCg5tobowAHNkSY7nMnl7ipVjQvkNU=; b=EV0hkV94hv8/eeKNUVCXWCs6P4Pq12fflmiacgus7rwnZBeWe3fj+4XjTKnjMFSoG7 hzbNtniJKXEOrpaCXX5zy+lNptz5ObCG9WniQ5BBS2oZFrLp/uYBXyzJ6FmB097ssjbA mn/m85s1tVRd/6kUzY88jNnZ2lgE9SdKwAhqWnntHe/6BZQKDjl9yYu7RzkOPTfD8fEl zolr6ti8aIkwx6iG9XhZWxoJr5EWdHABMTlUTA8c45IS9zlaMuhKUfE4jSOCEY0t4Ew7 zZZ1KpdnOdzXRkdYk4AS1/Tk5uc/pQbgf6sxUhWhZ0YGSEJpc12TEEFPuWY46efbepQT fjNA== X-Forwarded-Encrypted: i=1; AJvYcCVCf6ws5u/ytc9dPoQN6TtTif125fj2bq2qBQnNcDsnndF2tHc40t04sxnAtJ1+phQsuOrTfCcOtQ==@kvack.org X-Gm-Message-State: AOJu0YxcGYDDKEMwtuCZRvpgZMkyLHmLi1klsvGAM+emX7DhUwrO21F6 IKZZG8AHL8RvKl2phwb/3fHxqo/apboFbbpiuuXz76UTuJhlHUyotpDrLFp+KA4= X-Google-Smtp-Source: AGHT+IGzYJOejjtuqJo0nJ1nynkWMnHU8ii7Rd3gZibJ6Lwzw36puDjCRZ94B0e+iKiVQIQOOVVwsA== X-Received: by 2002:a05:6870:80ce:b0:288:57fa:961d with SMTP id 586e51a60fabf-288edfb72femr5245852fac.38.1729145928950; Wed, 16 Oct 2024 23:18:48 -0700 (PDT) Received: from GQ6QX3JCW2.bytedance.net ([203.208.189.10]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7ea9c6c442bsm4259549a12.28.2024.10.16.23.18.45 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 16 Oct 2024 23:18:48 -0700 (PDT) From: lizhe.67@bytedance.com To: willy@infradead.org Cc: akpm@linux-foundation.org, boqun.feng@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lizhe.67@bytedance.com, longman@redhat.com, mingo@redhat.com, peterz@infradead.org, will@kernel.org Subject: Re: [RFC 2/2] khugepaged: use upgrade_read() to optimize collapse_huge_page Date: Thu, 17 Oct 2024 14:18:41 +0800 Message-ID: <20241017061841.81240-1-lizhe.67@bytedance.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 7F27520003 X-Rspamd-Server: rspam01 X-Stat-Signature: 7k1smx8segg5rnikint1zkwsqmer4e69 X-HE-Tag: 1729145925-461533 X-HE-Meta: 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 +IzRXFdB Jq7kD4tYeirBu7pnz+lLl2cHN3XKvQlZw4HuuIWEetwFVf+HWL8wHjQE3UJWupVGMc2ehdMD5PXRMn39fs04x8P/yaAR64hz2aGEsJRamc/LXLCmJzXutqE4oWb0/x9cc6/GBqMWNK8zDd5oeFjucKqHa/5GE8JbJQ1X0GetC+/JvsvmsTi02DR8aLulCae/C8Ed4m/KvF886Zu0900Gr+7LyuaYlKbMC8DHCJL/q7YeqcvjELAkoR51k22CIpdZoiZYhMxyPeZE6Jlf4RzrVcriLoZ7Q9Gnrsj3x6AixDDQ4T0vx5TJkWdLlMsaZLjSnMHoU3hP/8eHfe27byTvGwtZqqJclfjXazP2P/Nxr2vsNQ2vOxCLPCxFgCIcRXbuyt7QzCCERGkaqpMJUqq4tBr2PhO31NBnQ1I5ISzV5BwtJWD4/wSpZ1qEcb7qhyyVyHaa/vQ0n4JSw1Zb6nYmVQZ7R1qLNjCBQSNfOiLny2oJ0xzw= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000012, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 16 Oct 2024 12:53:15 +0100, willy@infradead.org wrote: >On Wed, Oct 16, 2024 at 12:36:00PM +0800, lizhe.67@bytedance.com wrote: >> From: Li Zhe >> >> In function collapse_huge_page(), we drop mmap read lock and get >> mmap write lock to prevent most accesses to pagetables. There is >> a small time window to allow other tasks to acquire the mmap lock. >> With the use of upgrade_read(), we don't need to check vma and pmd >> again in most cases. > >This is clearly a performance optimisation. So you must have some >numebrs that justify this, please include them. Yes, I will add the relevant data to v2 patch. Thanks!