On 02/02/2016 05:21 PM, Ben Pfaff wrote: > On Tue, Feb 02, 2016 at 05:01:35PM -0500, Russell Bryant wrote: >> 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. > > Yes, I forgot to mention that #2 iterates until you reach a fixed point. > > I guess I'll ack this quickly when it reaches non-RFC. >
You can ACK it now if you're happy with it and you'd like to skip the formality. I was only going to update comment text based on our discussion here about "flood fill". -- Russell Bryant _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
