2015-05-12 23:20 GMT+02:00 Joe Stringer <joestrin...@nicira.com>: > On 12 May 2015 at 11:59, luc <mluc.2...@gmail.com> wrote: > > Hello team > > > > I am trying to work deeper into the code level of OVS. and what I would > > like to do is the following: > > > > For the receiving packet, if there is no matching rule in the flow table > > (i.e. packet is sent to user space and further sent to the sdn > controller), > > I would like to print out a message; otherwise, if there is matching > rule, > > print something else. > > > > So, in the code, I think datapath.c, ovs_dp_process_packet_with_key() > does > > the trick, the refered code is as following. Then, what I did is to send > > periodically the same kind of packet to the OVS machine (all the tested > > machines are built in VMs). > > > > However, I see that whenever I send my packet in a bit slow-speed (e.g. > one > > packet per 1 or 2 second), it always print out "flow entry is *NOT > *found", > > but indeed, I can really confirm by command line that the respective flow > > entry (also by wireshark at sdn controller, there is no PktIn any more > for > > these packets); But, when I send my packet a bit faster, e.g. one packet > > per 0.5 second, then, I'm able to get the expected output message "flow > > entry is found". > > > > Can anyone help me to explain why does that happen? and I pretty much > > appreciate if you can point me into the right direction... > > ovs-vswitchd manages the kernel datapath flows based on a variety of > factors including packet rate, so it's possible that at low packet > rates the flow is evicted for some reason. Depending on the version of > OVS, the logic of this differs, but you should be able to find it in > ofproto/ofproto-dpif-upcall.c. You can also turn the 'dpif' logging up > to debug level and observe flow adds/deletes in the ovs-vswitchd.log. >
Hi, Very appreciate your hints.. I searched around both in the code and also in Internet, and found one slide as attachment.. one thing I am still confused is that: from the slide, it says "*decision about how to process packet is made in userspace*", does it mean that whenever there is an incoming packet (no matter it is the first one in a flow or not), it always first goes to the user space ??? ps, the ovs version I am using is 2.3.1. Thanks a lot for some info. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
