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=-8.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 3F1B0C433E7 for ; Wed, 2 Sep 2020 16:54:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C6A720767 for ; Wed, 2 Sep 2020 16:54:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727897AbgIBQyq (ORCPT ); Wed, 2 Sep 2020 12:54:46 -0400 Received: from correo.us.es ([193.147.175.20]:40868 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726293AbgIBQyq (ORCPT ); Wed, 2 Sep 2020 12:54:46 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id AB26B8C3C46 for ; Wed, 2 Sep 2020 18:54:44 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 9BF6EDA73D for ; Wed, 2 Sep 2020 18:54:44 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id 918C6DA72F; Wed, 2 Sep 2020 18:54:44 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 8022DDA73F; Wed, 2 Sep 2020 18:54:42 +0200 (CEST) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Wed, 02 Sep 2020 18:54:42 +0200 (CEST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from us.es (unknown [90.77.255.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: 1984lsi) by entrada.int (Postfix) with ESMTPSA id 648B642EF42B; Wed, 2 Sep 2020 18:54:42 +0200 (CEST) Date: Wed, 2 Sep 2020 18:54:42 +0200 X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: Phil Sutter , netfilter-devel@vger.kernel.org, eric@garver.life Subject: Re: [PATCH nf,v3] netfilter: nf_tables: coalesce multiple notifications into one skbuff Message-ID: <20200902165442.GA19460@salvia> References: <20200902163743.18697-1-pablo@netfilter.org> <20200902163934.GF23632@orbyte.nwl.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200902163934.GF23632@orbyte.nwl.cc> User-Agent: Mutt/1.10.1 (2018-07-13) X-Virus-Scanned: ClamAV using ClamSMTP Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Wed, Sep 02, 2020 at 06:39:34PM +0200, Phil Sutter wrote: > On Wed, Sep 02, 2020 at 06:37:43PM +0200, Pablo Neira Ayuso wrote: > > On x86_64, each notification results in one skbuff allocation which > > consumes at least 768 bytes due to the skbuff overhead. > > > > This patch coalesces several notifications into one single skbuff, so > > each notification consumes at least ~211 bytes, that ~3.5 times less > > memory consumption. As a result, this is reducing the chances to exhaust > > the netlink socket receive buffer. > > > > Rule of thumb is that each notification batch only contains netlink > > messages whose report flag is the same, nfnetlink_send() requires this > > to do appropriately delivery to userspace, either via unicast (echo > > mode) or multicast (monitor mode). > > > > The skbuff control buffer is used to annotate the report flag for later > > handling at the new coalescing routine. > > > > The batch skbuff notification size is NLMSG_GOODSIZE, using a larger > > skbuff would allow for more socket receiver buffer savings (to amortize > > the cost of the skbuff even more), however, going over that size might > > break userspace applications, so let's be conservative and stick to > > NLMSG_GOODSIZE. > > > > Reported-by: Phil Sutter > > Signed-off-by: Pablo Neira Ayuso > > Acked-by: Phil Sutter Thanks, I'll place this into nf.git BTW, I assume this mitigates the problem that Eric reported? Is it not so easy to trigger the problem after this patch? I forgot to say, probably it would be good to monitor /proc/net/netlink to catch how busy the socket receive buffer is getting with your firewalld ruleset. Thanks.