From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:237:300::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 71AFBAB for ; Mon, 11 Dec 2023 17:09:30 -0800 (PST) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1rCrH6-0004IY-3z for netfilter-devel@vger.kernel.org; Tue, 12 Dec 2023 02:09:28 +0100 Date: Tue, 12 Dec 2023 02:09:28 +0100 From: Florian Westphal To: Netfilter Development Subject: Re: Should we keep the advice to increase queue max length? Message-ID: <20231212010928.GA16434@breakpoint.cc> References: Precedence: bulk X-Mailing-List: netfilter-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Duncan Roe wrote: > /proc/net/netfilter/nfnetlink_queue has a line for every active queue. The 3rd > field is the number of queued packets. The max length is not in these lines but > kernel source suggests it is 1024 by default. Anyway, I updated nfq6 to be able > to set the max (using mnl functions). > > And I found the maximum number of queued packets is: 238. Further packets are > dropped. > > If I lower the max below 238, limiting occurs at the new max. > > So I propose to drop the advice to increase the queue max length when I revise > the libnetfilter_queue main page as part of the project to stop using > libnfnetlink. > > Anyone have any comments? This code is very old, it stems from a time where the network stack did not do any kind of packet aggregation. I think the hint should be removed as you suggest.