On Fri, Jun 24, 2016 at 08:52:07PM -0700, Ben Pfaff wrote: > On Thu, Jun 23, 2016 at 01:56:59PM -0400, Hui Kang wrote: > > > > Hi, > > In our scalability test for OVN, we observed an in-scalable behaviour of > > the > > ovn-northd process: the time binding a logical port increases as # of large > > port increasing, regardless of whether logical ports belong to the same > > logical > > switch. The most suspicious function in causing this issue is build_ports() > > called by ovnnb_db_run() [1], as described below. > > > > Test description: > > step 1: Create 6 logical switches. For each logical switch, create 200 > > logical ports. > > step 2: Bind 200 lports from each logical switch on an OVN chassis. > > > > Test results for step 2: > > > > # of ports | # of ovn_ports | Cpu cycle spent in | > > | allocated in build_port() | built_port(), in million | > > 200 | 200 | 25 | > > 400 | 400 | 50 | > > 600 | 600 | 75 | > > 800 | 800 | 93 | > > 1000 | 1000 | 108 | > > 1200 | 1200 | 125 | > > I'm surprised that this is expensive for so few ports. I believe that > build_ports() runs in O(n) time where n is the larger of the number of > ports in the northbound and southbound databases. Does anyone see > anything that would cause quadratic or more regressive behavior there?
Actually, I take that back. The cycles/port for all the cases above demonstrate only slightly nonlinear scaling: 200/25 is 8 Mcycles/port, 1200/125 is 9.6 Mcycles/port. So the issue is not that it does not scale. The issue is that it is slow. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
