Re: [ovs-discuss] ovn-controller is taking 100% CPU all the time in one deployment
On Sat, Aug 31, 2019 at 2:48 AM Han Zhou wrote: > > > On Thu, Aug 29, 2019 at 11:36 PM Numan Siddique > wrote: > > > > > > > > On Fri, Aug 30, 2019 at 1:04 AM Han Zhou wrote: > >> > >> > >> > >> On Thu, Aug 29, 2019 at 12:16 PM Numan Siddique > wrote: > >>> > >>> > >>> > >>> On Fri, Aug 30, 2019 at 12:37 AM Han Zhou wrote: > > > > On Thu, Aug 29, 2019 at 11:40 AM Numan Siddique > wrote: > > > > Hello Everyone, > > > > In one of the OVN deployments, we are seeing 100% CPU usage by > ovn-controllers all the time. > > > > After investigations we found the below > > > > - ovn-controller is taking more than 20 seconds to complete full > loop (mainly in lflow_run() function) > > > > - The physical switch is sending GARPs periodically every 10 > seconds. > > > > - There is ovn-bridge-mappings configured and these GARP packets > reaches br-int via the patch port. > > > > - We have a flow in router pipeline which applies the action - > put_arp > > if it is arp packet. > > > > - ovn-controller pinctrl thread receives these garps, stores the > learnt mac-ips in the 'put_mac_bindings' hmap and notifies the > ovn-controller main thread by incrementing the seq no. > > > > - In the ovn-controller main thread, after lflow_run() finishes, > pinctrl_wait() is called. This function calls - poll_immediate_wake() as > 'put_mac_bindings' hmap is not empty. > > > > - This causes the ovn-controller poll_block() to not sleep at all > and this repeats all the time resulting in 100% cpu usage. > > > > The deployment has OVS/OVN 2.9. We have back ported the > pinctrl_thread patch. > > > > Some time back I had reported an issue about lflow_run() taking lot > of time - > https://mail.openvswitch.org/pipermail/ovs-dev/2019-July/360414.html > > > > I think we need to improve the logical processing sooner or later. > > > > But to fix this issue urgently, we are thinking of the below > approach. > > > > - pinctrl_thread will locally cache the mac_binding entries (just > like it caches the dns entries). (Please note pinctrl_thread can not access > the SB DB IDL). > > > > - Upon receiving any arp packet (via the put_arp action), > pinctrl_thread will check the local mac_binding cache and will only wake up > the main ovn-controller thread only if the mac_binding update is required. > > > > This approach will solve the issue since the MAC sent by the > physical switches will not change. So there is no need to wake up > ovn-controller main thread. > > > > In the present master/2.12 these GARPs will not cause this 100% cpu > loop issue because incremental processing will not recompute flows. > > > > Even though the above approach is not really required for > master/2.12, I think it is still Ok to have this as there is no harm. > > > > I would like to know your comments and any concerns if any. > > > > Thanks > > Numan > > > > Hi Numan, > > I think this approach should work. Just to make sure, to update the > cache efficiently (to avoid another kind of recompute), it should use ovsdb > change-tracking to update it incrementally. > > Regarding master/2.12, it is not harmful except that it will add some > more code and increase memory footprint. For our current use cases, there > can be easily 10,000s mac_bindings, but it may still be ok because each > entry is very small. However, is there any benefit for doing this in > master/2.12? > >>> > >>> > >>> I don't see much benefit. But I can't submit a patch to branch 2.9 > without the fix getting merged in master first right ? > >>> May be once it is merged in branch 2.9, we can consider to delete it ? > >>> > >> I think it is just about how would you maintain a downstream branch. > Since it is downstream, I don't think you need a change to be in upstream > before fixing a problem. In this case it may be *no harm*, but what if the > upstream is completely changed and incompatible for such a fix any more? It > shouldn't prevent you from fixing your downstream. (Of course it is better > to not have downstream at all, but sometimes it is useful to have it for a > temporary period, and since you (and us, too) are already there ... :) > > > > > > The dowstream 2.9 what we have is - OVS 2.9.0 + a bunch of patches (to > fix issues) which are already merged upstream (preferably upstream branch > or at least upstream master). Any downstream only patch is frowned upon. > When we updrade to 2.10 or higher versions there is a risk of functional > changes if the patch is not upstream. > > > > If we have apply the approach I described above to downstream 2.9 then > there is definitely some functional change. When such GARPs are received, > in the case of our downstream 2.9 we will not wake up ovn-controller main > thread > >
Re: [ovs-discuss] GRE with link-local remote_ip: "not a valid IPv6 address"
Am 28.08.19 um 19:26 schrieb Ben Pfaff: > On Tue, Aug 27, 2019 at 12:09:14PM +0200, Sven Gebauer wrote: >> Hi all, >> >> I'm trying to create a GRE tunnel with an IPv6 link-local address as the >> remote_ip. According to the changelog, this should be supported since >> v2.8.0. However... > > IPv6 link-local addresses are supported for use in contexts where OVS is > creating a socket, most notably for connections to controllers. In > other contexts, there's nowhere for OVS to put the scope, so it can't > support it. In this case, the kernel flow structure doesn't have a > scope in it, so there's nothing that userspace OVS can do about it. If > this feature were to be added, it would require adding the scope > (probably in multiple places) to that kernel flow structure, which would > probably be difficult for reasons of backward compatibility and > coordination with (and justification to) the kernel network stack > developers. > Ah, i see. Thank you! ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
Re: [ovs-discuss] [ovs-dev] ovn-controller is taking 100% CPU all the time in one deployment
Hi Han,
On Fri, Aug 30, 2019 at 10:37 PM Han Zhou wrote:
>
> On Fri, Aug 30, 2019 at 1:25 PM Numan Siddique wrote:
> >
> > Hi Han,
> >
> > I am thinking of this approach to solve this problem. I still need to
> test it.
> > If you have any comments or concerns do let me know.
> >
> >
> > **
> > diff --git a/northd/ovn-northd.c b/northd/ovn-northd.c
> > index 9a282..a83b56362 100644
> > --- a/northd/ovn-northd.c
> > +++ b/northd/ovn-northd.c
> > @@ -6552,6 +6552,41 @@ build_lrouter_flows(struct hmap *datapaths, struct
> hmap *ports,
> >
> > }
> >
> > +/* Handle GARP reply packets received on a distributed router
> gateway
> > + * port. GARP reply broadcast packets could be sent by external
> > + * switches. We don't want them to be handled by all the
> > + * ovn-controllers if they receive it. So add a priority-92 flow
> to
> > + * apply the put_arp action on a redirect chassis and drop it on
> > + * other chassis.
> > + * Note that we are already adding a priority-90 logical flow in
> the
> > + * table S_ROUTER_IN_IP_INPUT to apply the put_arp action if
> > + * arp.op == 2.
> > + * */
> > +if (op->od->l3dgw_port && op == op->od->l3dgw_port
> > +&& op->od->l3redirect_port) {
> > +for (int i = 0; i < op->lrp_networks.n_ipv4_addrs; i++) {
> > +ds_clear();
> > +ds_put_format(,
> > + "inport == %s && is_chassis_resident(%s)
> && "
> > + "eth.bcast && arp.op == 2 && arp.spa ==
> %s/%u",
> > + op->json_key,
> op->od->l3redirect_port->json_key,
> > + op->lrp_networks.ipv4_addrs[i].network_s,
> > + op->lrp_networks.ipv4_addrs[i].plen);
> > +ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 92,
> > + ds_cstr(),
> > + "put_arp(inport, arp.spa, arp.sha);");
> > +ds_clear();
> > +ds_put_format(,
> > + "inport == %s && !is_chassis_resident(%s)
> && "
> > + "eth.bcast && arp.op == 2 && arp.spa ==
> %s/%u",
> > + op->json_key,
> op->od->l3redirect_port->json_key,
> > + op->lrp_networks.ipv4_addrs[i].network_s,
> > + op->lrp_networks.ipv4_addrs[i].plen);
> > +ovn_lflow_add(lflows, op->od, S_ROUTER_IN_IP_INPUT, 92,
> > + ds_cstr(), "drop;");
> > +}
> > +}
> > +
> > /* A set to hold all load-balancer vips that need ARP responses.
> */
> > struct sset all_ips = SSET_INITIALIZER(_ips);
> > int addr_family;
> > *
> >
> > If a physical switch sends GARP request packets we have existing logical
> flows
> > which handle them only on the gateway chassis.
> >
> > But if the physical switch sends GARP reply packets, then these packets
> > are handled by ovn-controllers where bridge mappings are configured.
> > I think its good enough if the gateway chassis handles these packet.
> >
> > In the deployment where we are seeing this issue, the physical switch
> sends GARP reply
> > packets.
> >
> > Thanks
> > Numan
> >
> >
> Hi Numan,
>
> I think both GARP request and reply should be handled on all chassises. It
> should work not only for physical switch, but also for virtual workloads.
> At least our current use cases relies on that.
I believe that Numan's patch will not change the behavior for virtual
(OVN) workloads, does it?
Although I'm in favor of this patch, I still think that it's not
enough for non-Incremental Processing versions of OVS because even
we're going to release pressure on the compute nodes, still on loaded
systems, the gateway nodes are going to be hogging the CPU. Plus, I
think there's value even from a security standpoint in having it on
stable branches as it looks like a simple attack vector.
>
> Thanks,
> Han
> ___
> dev mailing list
> d...@openvswitch.org
> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
___
discuss mailing list
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Re: [ovs-discuss] [ovs-dev] ovn-controller is taking 100% CPU all the time in one deployment
On Fri, Aug 30, 2019 at 8:18 PM Han Zhou wrote: > > > > On Fri, Aug 30, 2019 at 6:46 AM Mark Michelson wrote: > > > > On 8/30/19 5:39 AM, Daniel Alvarez Sanchez wrote: > > > On Thu, Aug 29, 2019 at 10:01 PM Mark Michelson > > > wrote: > > >> > > >> On 8/29/19 2:39 PM, Numan Siddique wrote: > > >>> Hello Everyone, > > >>> > > >>> In one of the OVN deployments, we are seeing 100% CPU usage by > > >>> ovn-controllers all the time. > > >>> > > >>> After investigations we found the below > > >>> > > >>>- ovn-controller is taking more than 20 seconds to complete full loop > > >>> (mainly in lflow_run() function) > > >>> > > >>>- The physical switch is sending GARPs periodically every 10 seconds. > > >>> > > >>>- There is ovn-bridge-mappings configured and these GARP packets > > >>> reaches br-int via the patch port. > > >>> > > >>>- We have a flow in router pipeline which applies the action - > > >>> put_arp > > >>> if it is arp packet. > > >>> > > >>>- ovn-controller pinctrl thread receives these garps, stores the > > >>> learnt mac-ips in the 'put_mac_bindings' hmap and notifies the > > >>> ovn-controller main thread by incrementing the seq no. > > >>> > > >>>- In the ovn-controller main thread, after lflow_run() finishes, > > >>> pinctrl_wait() is called. This function calls - poll_immediate_wake() as > > >>> 'put_mac_bindings' hmap is not empty. > > >>> > > >>> - This causes the ovn-controller poll_block() to not sleep at all and > > >>> this repeats all the time resulting in 100% cpu usage. > > >>> > > >>> The deployment has OVS/OVN 2.9. We have back ported the pinctrl_thread > > >>> patch. > > >>> > > >>> Some time back I had reported an issue about lflow_run() taking lot of > > >>> time - > > >>> https://mail.openvswitch.org/pipermail/ovs-dev/2019-July/360414.html > > >>> > > >>> I think we need to improve the logical processing sooner or later. > > >> > > >> I agree that this is very important. I know that logical flow processing > > >> is the biggest bottleneck for ovn-controller, but 20 seconds is just > > >> ridiculous. In your scale testing, you found that lflow_run() was taking > > >> 10 seconds to complete. > > > I support this statement 100% (20 seconds is just ridiculous). To be > > > precise, in this deployment we see over 23 seconds for the main loop > > > to process and I've seen even 30 seconds some times. I've been talking > > > to Numan these days about this issue and I support profiling this > > > actual deployment so that we can figure out how incremental processing > > > would help. > > > > > >> > > >> I'm curious if there are any factors in this particular deployment's > > >> configuration that might contribute to this. For instance, does this > > >> deployment have a glut of ACLs? Are they not using port groups? > > > They're not using port groups because it's 2.9 and it is not there. > > > However, I don't think port groups would make a big difference in > > > terms of ovn-controller computation. I might be wrong but Port Groups > > > help reduce the number of ACLs in the NB database while the # of > > > Logical Flows would still remain the same. We'll try to get the > > > contents of the NB database and figure out what's killing it. > > > > > > > You're right that port groups won't reduce the number of logical flows. > > I think port-group reduces number of logical flows significantly, and also > reduces OVS flows when conjunctive matches are effective. Right, definitely the number of lflows will be much lower. My bad as I was directly involved in this! :) I was just thinking that the number of OVS flows will remain the same so the computation for ovn-controller would be similar but I missed the conjunctive matches part in my statement. > Please see my calculation here: > https://www.slideshare.net/hanzhou1978/large-scale-overlay-networks-with-ovn-problems-and-solutions/30 > > > However, it can reduce the computation in ovn-controller. The reason is > > that the logical flows generated by ACLs that use port groups may result > > in conjunctive matches being used. If you want a bit more information, > > see the "Port groups" section of this blog post I wrote: > > > > https://developers.redhat.com/blog/2019/01/02/performance-improvements-in-ovn-past-and-future/ > > > > The TL;DR is that with port groups, I saw the number of OpenFlow flows > > generated by ovn-controller drop by 3 orders of magnitude. And that > > meant that flow processing was 99% faster for large networks. > > > > You may not see the same sort of improvement for this deployment, mainly > > because my test case was tailored to illustrate how port groups help. > > There may be other factors in this deployment that complicate flow > > processing. > > > > >> > > >> This particular deployment's configuration may give us a good scenario > > >> for our testing to improve lflow processing time. > > > Absolutely! > > >> > > >>> > > >>> But to fix this issue urgently, we are thinking of the
