On Nov 15, 2012, at 3:32 PM, Kyle Mestery (kmestery) <kmest...@cisco.com> wrote: > On Nov 15, 2012, at 3:13 PM, Kyle Mestery (kmestery) <kmest...@cisco.com> > wrote: >> On Nov 15, 2012, at 1:03 PM, Kyle Mestery (kmestery) <kmest...@cisco.com> >> wrote: >>> Jesse: >>> >>> I modified the source port hashing for the VXLAN patch I submitted a few >>> days ago, >>> but I've noticed when using the upstream source port hashing routine, >>> performance >>> drops off by 3.5 times when using iperf between two VMs. From what I can >>> tell, it >>> has to be that all skbuffs coming into the VXLAN tunnel have not already >>> had their >>> rxhash set, and this function is what's killing performance. Let me share >>> the details: >>> >> I think I figured this out. The upstream source port selection algorithm is >> exploding flows >> in the fast path. Here are iperf runs with both and subsequent "ovs-dpctl >> dump-flows" >> commands for comparison. The first one is with the upstream version, the >> second is >> with the one in my patch. Note that I just piped "ovs-dpctl dump-flows" into >> wc to >> summarize the flow count. >> >> Upstream verison: >> [root@linux-br ~]# iperf -c 10.1.2.14 && ovs-dpctl dump-flows | wc > > > Figured this out, fixing it now, will repost the patch with only this change > soon. >
So after looking at this, the upstream source port selection function will cause an explosion of fast path flows due to an ever changing skbuff->rxhash. By using the flow->hash, we don't see this problem. Jesse, any comments on this particular issue? I think using the upstream function will allow for greater spreading across links depending on the hashing algorithm used on upstream switches, but will cause this flow explosion on the host itself. Thanks, Kyle > Thanks, > Kyle > _______________________________________________ > dev mailing list > dev@openvswitch.org > http://openvswitch.org/mailman/listinfo/dev _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
