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] ovn-controller is taking 100% CPU all the time in one deployment
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. 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 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. I think this can work well. We have a lot of what's needed already in pinctrl at this point. We have the hash table of mac bindings already. Currently, we flush this table after we write the data to the southbound database. Instead, we would keep the bindings in memory. We would need to ensure that the in-memory MAC bindings eventually get deleted if they become stale. In the present master/2.12 these GARPs will not cause this 100% cpu loop issue because incremental processing will not recompute flows. Another mitigating factor for master is something I'm currently working on. I've got the beginnings of a patch series going where I am separating pinctrl into a separate process from
Re: [ovs-discuss] ovn-controller is taking 100% CPU all the time in one deployment
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. > > 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 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. > > I think this can work well. We have a lot of what's needed already in > pinctrl at this point. We have the hash table of mac bindings already. > Currently, we flush this table after we write the data to the southbound > database. Instead, we would keep the bindings in memory. We would need > to ensure that the in-memory MAC bindings eventually get deleted if they > become stale. > > > > > In the present master/2.12 these GARPs will not cause this 100% cpu loop > > issue because incremental processing will not recompute flows. > > Another mitigating factor for master is something I'm currently working > on. I've got the beginnings of a patch series going where I am > separating pinctrl into a separate process from ovn-controller: > https://github.com/putnopvut/ovn/tree/pinctrl_process > > It's in the early stages right now, so please don't judge :) > > Separating pinctrl to its own process means that it cannot directly > cause ovn-controller to wake up like it currently might. > > > > > 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. > > Hm, I don't really understand why we'd want to put this in master/2.12 > if the problem doesn't exist there. The main concern I have is with > regards to cache lifetime. I don't want to introduce potential memory > growth concerns
Re: [ovs-discuss] ovn-controller is taking 100% CPU all the time in one deployment
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 but with 2.12/master, we wake up the ovn-controller main thread. I still see no harm in having this in upstream master. May be instead of having a complete clone of mac_bindings, we can have a subset of mac_bindings cached only if those mac_bindings are learnt by an ovn-controller. I will explore more. Thanks Numan
Re: [ovs-discuss] ovn-controller is taking 100% CPU all the time in one deployment
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'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? This particular deployment's configuration may give us a good scenario for our testing to improve lflow processing time. 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. I think this can work well. We have a lot of what's needed already in pinctrl at this point. We have the hash table of mac bindings already. Currently, we flush this table after we write the data to the southbound database. Instead, we would keep the bindings in memory. We would need to ensure that the in-memory MAC bindings eventually get deleted if they become stale. In the present master/2.12 these GARPs will not cause this 100% cpu loop issue because incremental processing will not recompute flows. Another mitigating factor for master is something I'm currently working on. I've got the beginnings of a patch series going where I am separating pinctrl into a separate process from ovn-controller: https://github.com/putnopvut/ovn/tree/pinctrl_process It's in the early stages right now, so please don't judge :) Separating pinctrl to its own process means that it cannot directly cause ovn-controller to wake up like it currently might. 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. Hm, I don't really understand why we'd want to put this in master/2.12 if the problem doesn't exist there. The main concern I have is with regards to cache lifetime. I don't want to introduce potential memory growth concerns into a branch if it's not necessary. Is there a way for us to get this included in 2.9-2.11 without having to put it in master or 2.12? It's hard to classify this as a bug fix, really, but it does prevent unwanted behavior in real-world setups. Could we get an opinion from committers on this? Thanks Numan ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
Re: [ovs-discuss] ovn-controller is taking 100% CPU all the time in one deployment
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 ... :) ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
Re: [ovs-discuss] ovn-controller is taking 100% CPU all the time in one deployment
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 ? Thanks Numan > > Thanks, > Han > > ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
Re: [ovs-discuss] ovn-controller is taking 100% CPU all the time in one deployment
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? Thanks, Han ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
[ovs-discuss] ovn-controller is taking 100% CPU all the time in one deployment
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 ___ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
