On Sat, 9 Jul 2016 11:35:03 -0400 Hannes Frederic Sowa <han...@stressinduktion.org> wrote: > On 09.07.2016 11:18, Shmulik Ladkani wrote: > > On Fri, 8 Jul 2016 19:04:27 -0400 Hannes Frederic Sowa > > <han...@stressinduktion.org> 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