"dev" <dev-boun...@openvswitch.org> wrote on 06/23/2016 12:56:59 PM:
> From: Hui Kang/Watson/IBM@IBMUS > To: dev@openvswitch.org > Date: 06/23/2016 12:57 PM > Subject: [ovs-dev] [OVN] Potential scalability bug in ovn-northd on > creating and binding large number of lports > Sent by: "dev" <dev-boun...@openvswitch.org> > > > 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 | > > We see that on binding each logical port on a hypervisor, > join_logical_ports() > in build_port allocates the number of (struct ovn_port) for all the > existing > ports in the southbound database [2], which causes the accumulated CPU > cycles. > > My question is whether there is any particular reason to allocate that > number > of (struct ovn_port)? It seems to me there is room in this code to optimize > for performance. Thanks. > > - Hui > > > [1] > https://github.com/openvswitch/ovs/blob/master/ovn/northd/ovn-northd.c#L2529 > [2] > https://github.com/openvswitch/ovs/blob/master/ovn/northd/ovn-northd.c#L571 Hui, ovn-northd's current design is that it processes the entire ovn nb db each computational cycle, so I would expect to see what you are seeing, which is the argument for converting ovn-northd to an incremental processing model. Ben, Justin, Yusheng can one of you talk to an ETA for when the nlog ovn-northd code base will start to land in the review queue? That will provide input on whether doing an interim patch series is worth the effort or not... Ryan _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
