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=-15.7 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 D6F34C433E6 for ; Tue, 2 Feb 2021 16:28:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A3BB364E9B for ; Tue, 2 Feb 2021 16:28:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236321AbhBBQ1V (ORCPT ); Tue, 2 Feb 2021 11:27:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51048 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236259AbhBBQYL (ORCPT ); Tue, 2 Feb 2021 11:24:11 -0500 Received: from mail-ej1-x62f.google.com (mail-ej1-x62f.google.com [IPv6:2a00:1450:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 908ABC061793 for ; Tue, 2 Feb 2021 08:20:21 -0800 (PST) Received: by mail-ej1-x62f.google.com with SMTP id a9so12471111ejr.2 for ; Tue, 02 Feb 2021 08:20:21 -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=5t8gF/7MnhThY2j1XM7SKo96HwlDRa32gOOq7/bZKJk=; b=Yvv5v4eG2LkMQCadSipNvPIGaWt32iEufCPauNGvLPSIkjlew/+iCWnBSKm9BDL7pY Na4uGGGjBoZ7+VZWp11Kgmll8Hmiqx80ZRc2sRB+BuoGwBhKDtMFuM1vnqjD84+9hxJZ JmlH04RqCKpzXcF8yb4rKRMK/Fmmhx+lwidhWTgQ1fwIw439WjT0nFgHD3E+azIAkbDM uYJD7xEbsxUrUCBZP7w4NKOBmyv5FcRUZEsVk5NMLsB9Exv09gHnCNZg/QFQwzjY12TN Emx5UA04WXpEjVZ81tyWDVDnEKHEZEsxp7aP5iuqObPBZXQoLD3M037vyu+R9t2GDv8Y M6kw== 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=5t8gF/7MnhThY2j1XM7SKo96HwlDRa32gOOq7/bZKJk=; b=b0Sv4CUT0G0eNGhtOYlZaKae+6LUrZC/Xz/PFQoKsYZbvde4lrfY+poSuWN2GE2c8U xpzeqLWvniDpwtkwKEcaIfTvmu0MoVSbvFu/dLIpOUULYZ5t1ohFOG/kahKBf2ZKXHn/ aSAIJIsJ/cnG5pnoNPdk7Ltmt9HKiVzPGcffXigpCcyeAdGYb2Od9hkyw+25ljR9+TdB pOa0kV4N/ZO80EfhUULZlYNN0cBhkzyNMBHiKsnbXtkG2J+3VAygkgLZVeuz1fIlnHNa lgjbyI0OBQy5UkKeMy9ulU54xK+Rp3ShO2t34LzknIjdZZ3fIEV0SFHxe2r3BwSzfHn/ EI+w== X-Gm-Message-State: AOAM5326O4GfF8ZOPwmFX4Lw4KPvbDeXTlV2bXcXYAMtByXLYxYAXgZ7 LjhcTj2w1t+cG5Wdn+h7yh4z9c9v558= X-Google-Smtp-Source: ABdhPJyCeA5ys0yDLUgfuCeGulGujR1MdxLBswTW7DwdiVLy3yWpG+bivqPOmCirpNMtgNhMhIgrVA== X-Received: by 2002:a17:906:c05a:: with SMTP id bm26mr24145314ejb.288.1612282820373; Tue, 02 Feb 2021 08:20:20 -0800 (PST) Received: from localhost.localdomain ([31.210.181.203]) by smtp.gmail.com with ESMTPSA id f3sm562450edt.24.2021.02.02.08.20.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Feb 2021 08:20:19 -0800 (PST) From: Amir Goldstein To: Jan Kara Cc: linux-fsdevel@vger.kernel.org Subject: [PATCH 5/7] fanotify: limit number of event merge attempts Date: Tue, 2 Feb 2021 18:20:08 +0200 Message-Id: <20210202162010.305971-6-amir73il@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210202162010.305971-1-amir73il@gmail.com> References: <20210202162010.305971-1-amir73il@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Event merges are expensive when event queue size is large. Limit the linear search to 128 merge tests. In combination with 128 hash lists, 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 12df6957e4d8..6d3807012851 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -129,11 +129,15 @@ static bool fanotify_should_merge(struct fsnotify_event *old_fsn, 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 list_head *list, struct fsnotify_event *event) { struct fsnotify_event *test_event; struct fanotify_event *new; + int i = 0; pr_debug("%s: list=%p event=%p\n", __func__, list, event); new = FANOTIFY_E(event); @@ -147,6 +151,8 @@ static int fanotify_merge(struct list_head *list, struct fsnotify_event *event) return 0; list_for_each_entry_reverse(test_event, list, list) { + if (++i > FANOTIFY_MAX_MERGE_EVENTS) + break; if (fanotify_should_merge(test_event, event)) { FANOTIFY_E(test_event)->mask |= new->mask; return 1; -- 2.25.1