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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7E0AFC47257 for ; Fri, 8 May 2020 12:23:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3A787208D6 for ; Fri, 8 May 2020 12:23:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="H0viADmU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A787208D6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2B8D3900005; Fri, 8 May 2020 08:23:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 24413900002; Fri, 8 May 2020 08:23:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 10DFF900005; Fri, 8 May 2020 08:23:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0060.hostedemail.com [216.40.44.60]) by kanga.kvack.org (Postfix) with ESMTP id E34CC900002 for ; Fri, 8 May 2020 08:23:26 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 9856F16902 for ; Fri, 8 May 2020 12:23:26 +0000 (UTC) X-FDA: 76793467212.27.mom11_583606bc53331 X-HE-Tag: mom11_583606bc53331 X-Filterd-Recvd-Size: 3673 Received: from forwardcorp1j.mail.yandex.net (forwardcorp1j.mail.yandex.net [5.45.199.163]) by imf12.hostedemail.com (Postfix) with ESMTP for ; Fri, 8 May 2020 12:23:26 +0000 (UTC) Received: from mxbackcorp1g.mail.yandex.net (mxbackcorp1g.mail.yandex.net [IPv6:2a02:6b8:0:1402::301]) by forwardcorp1j.mail.yandex.net (Yandex) with ESMTP id 38F662E0DD7; Fri, 8 May 2020 15:23:24 +0300 (MSK) Received: from myt5-70c90f7d6d7d.qloud-c.yandex.net (myt5-70c90f7d6d7d.qloud-c.yandex.net [2a02:6b8:c12:3e2c:0:640:70c9:f7d]) by mxbackcorp1g.mail.yandex.net (mxbackcorp/Yandex) with ESMTP id CwfcYZS86f-NNAWclZ0; Fri, 08 May 2020 15:23:24 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1588940604; bh=fE5H5nxfbTVPsDYqy95Pi0qrqxG0n44r6YkokVlYuxs=; h=In-Reply-To:Message-ID:References:Date:To:From:Subject:Cc; b=H0viADmU8Q1pZpdoq3gUEj+1k51lST+hEaXaQzaspjNPreBUobGD5qFJJFWjDTZGp qlxY2mfOF2tOueZPJ4/OWPOMlUWZTHdSiJAtumhD0dek8Lrtd2BO77fiuVy2fciQPS vEFgofTlKQcoOtSbRFNqyibCu/ALHX0go6vjdkiE= Authentication-Results: mxbackcorp1g.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-vpn.dhcp.yndx.net (dynamic-vpn.dhcp.yndx.net [2a02:6b8:b080:7008::1:4]) by myt5-70c90f7d6d7d.qloud-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id fhizLjzH9z-NNWe0AWK; Fri, 08 May 2020 15:23:23 +0300 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (Client certificate not present) Subject: [PATCH RFC 4/8] fsnotify: stop walking child dentries if remaining tail is negative From: Konstantin Khlebnikov To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Alexander Viro Cc: Waiman Long Date: Fri, 08 May 2020 15:23:23 +0300 Message-ID: <158894060308.200862.2000400345829882905.stgit@buzz> In-Reply-To: <158893941613.200862.4094521350329937435.stgit@buzz> References: <158893941613.200862.4094521350329937435.stgit@buzz> User-Agent: StGit/0.22-32-g6a05 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit 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 notification starts/stops listening events from inode's children it have to update dentry->d_flags of all positive child dentries. Scanning may took a long time if directory has a lot of negative child dentries. This is main beneficiary of sweeping cached negative dentries to the end. Before patch: nr_dentry = 24172597 24.2M nr_buckets = 8388608 2.9 avg nr_unused = 24158110 99.9% nr_negative = 24142810 99.9% inotify time: 0.507182 seconds After patch: nr_dentry = 24562747 24.6M nr_buckets = 8388608 2.9 avg nr_unused = 24548714 99.9% nr_negative = 24543867 99.9% inotify time: 0.000010 seconds Negative dentries no longer slow down inotify op at parent directory. Signed-off-by: Konstantin Khlebnikov --- fs/notify/fsnotify.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index 72d332ce8e12..072974302950 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -127,8 +127,12 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode) * original inode) */ spin_lock(&alias->d_lock); list_for_each_entry(child, &alias->d_subdirs, d_child) { - if (!child->d_inode) + if (!child->d_inode) { + /* all remaining children are negative */ + if (d_is_tail_negative(child)) + break; continue; + } spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); if (watched)