From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shmulik Ladkani Subject: Re: [PATCH net-next 0/4] net: cleanup for UDP tunnel's GRO Date: Sat, 9 Jul 2016 18:56:12 +0300 Message-ID: <20160709185612.77c39424@halley> References: <20160708231734.6258c00b@halley> <643a68e2-b3d8-a21b-79ff-9ba7b7c9f418@stressinduktion.org> <1dc81b88-47c9-4274-6275-490b16526d4a@stressinduktion.org> <20160709181816.1f601239@halley> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Jiri Benc , Alexander Duyck , Paolo Abeni , Netdev , "David S. Miller" , Jesse Gross , Tom Herbert To: Hannes Frederic Sowa Return-path: Received: from mail-wm0-f43.google.com ([74.125.82.43]:37939 "EHLO mail-wm0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751539AbcGIP4U (ORCPT ); Sat, 9 Jul 2016 11:56:20 -0400 Received: by mail-wm0-f43.google.com with SMTP id n127so44311715wme.1 for ; Sat, 09 Jul 2016 08:56:19 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Sat, 9 Jul 2016 11:35:03 -0400 Hannes Frederic Sowa wrote: > On 09.07.2016 11:18, Shmulik Ladkani wrote: > > On Fri, 8 Jul 2016 19:04:27 -0400 Hannes Frederic Sowa wrote: > >>>> I really do wonder if GRO on top of fragmentation does have any effect. > >>>> Would be great if someone has data for that already? > >>> > >>> I think that logic is kind of backwards. It is already there. > >>> Instead of asking people to prove that this change is invalid the onus > >>> should be on the submitter to prove the change causes no harm. > >> > >> Of course, sorry, I didn't want to make the impression others should do > >> that. I asked because Shmulik made the impression on me he had > >> experience with GRO+fragmentation on vxlan and/or geneve and could > >> provide some data, maybe even just anecdotal. > > > > Few anecdotal updates. > > > > I don't have ready-made data as the systems are not using this exact > > kind of of setup. > > > > However, by performing some quick experimentations, it reveals that GRO > > on top of the tunnels, where tunnel datagrams are fragmented, has some > > effect. The packets indeed get aggregated, although not aggresively as > > in the non-fragmented case. > > > > Whether the effect is significant depends on the system. > > > > In a system that is very sensitive to non-aggregated skbs (due to a cpu > > bottleneck during further processing of the decapsulated packets), the > > effect of aggregation is indeed significant. > > Cool, thanks. I thought it wouldn't happen because of the packet pacing. > We will also do some more tests ourselves. Maybe it is time to add > fragmentation support to inet_gro_receive to handle those cases much > more easily without going through fragmentation engine at all, would > probably speed up your usage significantly? Indeed, that seems beneficial. I wondered about this back ago. I found it not trivial, though. Without the transport headers available per received SKB, it makes GRO complex than currently is :) > Talking about ip fragmentation in general, are you end-host or > mid-router fragmented? Currently dealing with end-host fragmentation. (follow the thread at [1] - usecase is better explained there) [1] http://www.spinics.net/lists/netdev/msg385085.html Regards, Shmulik