From patchwork Thu Mar 4 10:48:26 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amir Goldstein X-Patchwork-Id: 12115849 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 2025DC43332 for ; Thu, 4 Mar 2021 10:50:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A7C664F2B for ; Thu, 4 Mar 2021 10:50:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239008AbhCDKtj (ORCPT ); Thu, 4 Mar 2021 05:49:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43466 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238975AbhCDKtT (ORCPT ); Thu, 4 Mar 2021 05:49:19 -0500 Received: from mail-wm1-x331.google.com (mail-wm1-x331.google.com [IPv6:2a00:1450:4864:20::331]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DA586C061764 for ; Thu, 4 Mar 2021 02:48:35 -0800 (PST) Received: by mail-wm1-x331.google.com with SMTP id n4so9169837wmq.3 for ; Thu, 04 Mar 2021 02:48:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=6inpK8e5gQdagMOstM4UZ+mo4MahSWvBmPFx6TwDxW4=; b=bW5RDsO32JReORhfQvJR6jAnM4epHERwx7GH3on64lCRwS1tUHrKv4sSYg8jzsA2nN K42ItI/bhig0iVlses8VkKLUA9oHA3HeaMmaol9Y3F6OtJWjDyXCgPMvVJhi1xH/wscO kkWcytwdfsWHqpH2ATrn78vV5ydgPfR4W4O3/zakE2UD6wO8QOMBxkf7oKs/0weyfcrV 0Z34IB3ZqToHn2127VzN6LfSeECYLdfediP8QiLpgI1Lgw2cJnhzgiZ01+KNStAORzhx g0i8FSEemATT4HUBIDSdH09xoTXlJfjhRbEM78mAr74e/UF1nqeziwGG8aorvqHfme+T WCHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=6inpK8e5gQdagMOstM4UZ+mo4MahSWvBmPFx6TwDxW4=; b=a0aVAVA3R90mGcbx06Su+v2pkdg1khgi8Rpe5yuf/+2gAa5JJqhe02PDaPEslHkNcc +p7OEohF+q4B8x5Es7p1N4kJKF+p1u09QRDg2nCNYVznEeGyr3av3TyG89JltUddvblx hTrIVt7bQhUytSADdfPlF76Kucg1zlhqORBNnWSsAw9CG3GSmAcmfwaTF94OdjNJfGQc LY+eQiUZvX0kgtKzOT+SE9Y6YfFuIdzHxBfY+H6A1f9rU4JqAo7PhZJazapaFvnHtLCW dzoOT7jYQpCewXGClDcFy3vmw/g4q8AFqw3WEINyh0S0pgig79flgK2cGb9LiD1yDa// Nr2w== X-Gm-Message-State: AOAM533rGMtsof6zqBSdDBMdoYx/osZ1o/g7VXLKxHdOg3t+tUEYNjtg uENcGLZU6nCUsjRtb1mRnmI= X-Google-Smtp-Source: ABdhPJzP0G5ClnOf55mlstos//LUep4FvocPfhVzOGQVEHZXyM5LG+caKT+bJOKTg8H9krQe9PyYHA== X-Received: by 2002:a1c:e084:: with SMTP id x126mr3280969wmg.37.1614854914615; Thu, 04 Mar 2021 02:48:34 -0800 (PST) Received: from localhost.localdomain ([141.226.13.117]) by smtp.gmail.com with ESMTPSA id d7sm6736635wrs.42.2021.03.04.02.48.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Mar 2021 02:48:34 -0800 (PST) From: Amir Goldstein To: Jan Kara Cc: linux-fsdevel@vger.kernel.org Subject: [PATCH v2 5/5] fanotify: limit number of event merge attempts Date: Thu, 4 Mar 2021 12:48:26 +0200 Message-Id: <20210304104826.3993892-6-amir73il@gmail.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210304104826.3993892-1-amir73il@gmail.com> References: <20210304104826.3993892-1-amir73il@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Event merges are expensive when event queue size is large, so limit the linear search to 128 merge tests. In combination with 128 size hash table, there is a potential to merge with up to 16K events in the hashed queue. Signed-off-by: Amir Goldstein --- fs/notify/fanotify/fanotify.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index 1795facc5439..e9384de29f6c 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -148,6 +148,9 @@ static bool fanotify_should_merge(struct fanotify_event *old, return false; } +/* Limit event merges to limit CPU overhead per event */ +#define FANOTIFY_MAX_MERGE_EVENTS 128 + /* and the list better be locked by something too! */ static int fanotify_merge(struct fsnotify_group *group, struct fsnotify_event *event) @@ -155,6 +158,7 @@ static int fanotify_merge(struct fsnotify_group *group, struct fanotify_event *old, *new = FANOTIFY_E(event); unsigned int bucket = fanotify_event_hash_bucket(group, new); struct hlist_head *hlist = &group->fanotify_data.merge_hash[bucket]; + int i = 0; pr_debug("%s: group=%p event=%p bucket=%u\n", __func__, group, event, bucket); @@ -168,6 +172,8 @@ static int fanotify_merge(struct fsnotify_group *group, return 0; hlist_for_each_entry(old, hlist, merge_list) { + if (++i > FANOTIFY_MAX_MERGE_EVENTS) + break; if (fanotify_should_merge(old, new)) { old->mask |= new->mask; return 1;