From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Philosophical question: Is a UDP multicast datagram for which there is no socket match a drop or an ignore? Date: Tue, 30 Sep 2014 16:09:37 -0700 Message-ID: <542B3831.5030701@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org Return-path: Received: from g4t3425.houston.hp.com ([15.201.208.53]:15638 "EHLO g4t3425.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751105AbaI3XJj (ORCPT ); Tue, 30 Sep 2014 19:09:39 -0400 Received: from g9t2301.houston.hp.com (g9t2301.houston.hp.com [16.216.185.78]) by g4t3425.houston.hp.com (Postfix) with ESMTP id E3710C3 for ; Tue, 30 Sep 2014 23:09:38 +0000 (UTC) Received: from [16.103.148.51] (tardy.usa.hp.com [16.103.148.51]) by g9t2301.houston.hp.com (Postfix) with ESMTP id B233F71 for ; Tue, 30 Sep 2014 23:09:38 +0000 (UTC) Sender: netdev-owner@vger.kernel.org List-ID: I've been looking at some additional perf -e skb_kfree_skb results, this time with a laptop connected to a corporate network with a large number of Windows systems sending out what they are wont to send... The laptop is just sitting there no active netperfs or anything :) I see profile hits for __udp4_lib_mcast_deliver() which has a kfree_skb() call which will happen if either there were no sockets found, or if an integral multiple of ARRAY_SIZE(stack) sockets are found. I'm assuming the latter is exceedingly rare. Anywho, the philosophical question - is such a situation a drop (indicating the existing kfree_skb()), or is it an ignore (indicating a consume_skb())? Should there be a statistic incremented for either of those? happy benchmarking, rick jones