From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: udp v6 early demux? Date: Tue, 10 Feb 2015 21:53:48 -0500 Message-ID: <54DAC43C.2090101@gmail.com> References: <54DA3C64.1060309@gmail.com> <1423589555.28434.36.camel@edumazet-glaptop2.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" To: Eric Dumazet Return-path: Received: from mail-qa0-f53.google.com ([209.85.216.53]:61498 "EHLO mail-qa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751256AbbBKCxu (ORCPT ); Tue, 10 Feb 2015 21:53:50 -0500 Received: by mail-qa0-f53.google.com with SMTP id k15so695062qaq.12 for ; Tue, 10 Feb 2015 18:53:50 -0800 (PST) In-Reply-To: <1423589555.28434.36.camel@edumazet-glaptop2.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: On 02/10/2015 12:32 PM, Eric Dumazet wrote: > On Tue, 2015-02-10 at 12:14 -0500, Vlad Yasevich wrote: >> Hi >> >> While testing udpv6 lockless path, I noticed that there is no >> support for udpv6 early demux? Is there a technical reason why, >> or was this just something that got forgotten (kind of like >> lockeless sendmsg)? > > If you have a use case for connected UDP ipv6 flows with performance > issues, then you might add early demux I guess. > > IPv4 udp early demux has been a bit of a hack actually, > as Shawn main usage was multicast AFAIK > > 63c6f81cdde5 udp: ipv4: do not waste time in __udp4_lib_mcast_demux_lookup > 610438b74496 udp: ipv4: fix potential use after free in udp_v4_early_demux() > f69b923a758f udp: fix a typo in __udp4_lib_mcast_demux_lookup > 421b3885bf6d udp: ipv4: Add udp early demux > > I was more wondering if we can avoid the route the lookup. It may not always be a connected a case. If you have multiple senders and a single receiver on the same subnet, avoiding the route lookup with early demux might help. -vlad