On Tue, Apr 18, 2017 at 08:09:08PM +0200, Hannes Frederic Sowa wrote: > > > On Tue, Apr 18, 2017, at 17:16, David Miller wrote: > > From: Simon Horman <simon.hor...@netronome.com> > > Date: Tue, 18 Apr 2017 17:09:04 +0900 > > > > > On Wed, Mar 08, 2017 at 11:22:01AM -0800, Eric Dumazet wrote: > > >> On Wed, 2017-03-08 at 12:11 -0700, Subash Abhinov Kasiviswanathan wrote: > > >> > On 2017-03-08 11:40, Eric Dumazet wrote: > > >> > > Well, this 'optimization' actually hurts when UDP sockets are not > > >> > > connected, since this adds an extra cache line miss per incoming > > >> > > packet. > > >> > > > > >> > > (DNS servers for example) > > >> > > > >> > Hi Eric > > >> > > > >> > Thanks for your comments. Would it be preferable to disable early > > >> > demux > > >> > for the > > >> > servers with large unconnected workloads in that case? > > >> > > >> Well, many servers handle both TCP and UDP. > > >> > > >> For TCP, there is no question about early demux, this is definitely a > > >> win. > > >> > > >> We probably should have one sysctl to enable TCP early demux, one for > > >> UDP early demux. > > > > > > If early demux is a clear win for TCP then I wonder if it is > > > unnecessary and by some leap also undesirable to have a configuration > > > knob for that case. > > > > For forwarding workloads it is pure overhead since the early demux will > > never find a local socket, and therefore it is wasted work. > > Also for some more complicated fib rules setups the early demux logic > could end up causing doing wrong lookups, because some route might not > be actually local in one fib rule but it is in another one.
Thanks for the clarification. Knobs for both TCP and UDP now make perfect sense to me.
