On 02/02/2016 04:49 PM, Ben Pfaff wrote: > On Thu, Jan 21, 2016 at 03:21:00PM -0500, Russell Bryant wrote: >> Previously, ovn-controller translated logical flows into OpenFlow flows >> for *every* logical datapath. This patch makes it so we skip doing so >> for the egress pipeline if the datapath is a logical switch with no >> logical ports bound locally. In that case, the flows have no effect. >> >> This was the code path taking the most time in a large scale OVN >> environment and was an easy optimization to make based on the existing >> local_datapaths info. >> >> In this environment, while idling, ovn-controller was taking up about >> 20% CPU with this patch, while other nodes were in the 40-70% range. >> >> Reported-at: https://bugs.launchpad.net/networking-ovn/+bug/1536003 >> Signed-off-by: Russell Bryant <russ...@ovn.org> >> Tested-by: Matt Mulsow <mailto:mamul...@us.ibm.com> >> --- >> >> >> As discussed in the OVN IRC meeting today, this is one patch I came up >> with while trying to analyze the performance in a large scale OVN >> test setup. It made a big impact for not much code. I know Ben had some >> suggestions for how to clean this up, so I'm just submitting as RFC for now. > > I think this is fine for now; we can optimize more later. > > However I get a compile error against current master, perhaps it has > moved on since you posted the patch: > > ../ovn/controller/ovn-controller.c: In function ‘main’: > ../ovn/controller/ovn-controller.c:300:54: error: ‘local_datapaths’ > undeclared (first use in this function) > lflow_run(&ctx, &flow_table, &ct_zones, &local_datapaths); > ^ > ../ovn/controller/ovn-controller.c:300:54: note: each undeclared > identifier is reported only once for each function it appears in
Yeah, I actually wrote this on top of this patch series: https://patchwork.ozlabs.org/bundle/russellb/localnet/ mainly because the scale test environment had those patches applied. > I think that the way to optimize this, in the end, is to use a kind of > "flood fill" algorithm: > > 1. Initialize set S to the logical datapaths that have a port > located on the hypervisor. > > 2. For each patch port P in a logical datapath in S, add the logical > datapath of the remote end of P to S. > > Extra credit if there's a way to infer (or specify) that a logical > datapath is "terminal", that is, that a packet that comes into it from a > different logical datapath will never come back out. right, because #2 needs to happen on every datapath added as a result of #2, as well. I'll incorporate some comments about this in the non-RFC submission. As I mentioned above, it's based on the localnet fixes from above, so I'll probably wait until those are merged. -- Russell Bryant _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
