[ovs-discuss] Warning logs flooding: failed to flow_del (No such file or directory)

Andrey Korolyov andrey at xdel.ru
Fri Oct 3 23:20:58 UTC 2014


On Thu, Jul 3, 2014 at 7:42 PM, Alex Wang <alexw at nicira.com> wrote:
> I'm not exactly sure about the dp flow you have...  but yes, del-flows
> will purge all flows.
>
> Also, if you stop to traffic that hitting the 'more inclusive' flow, then,
> both flows ('inclusive' and 'phantom') should be deleted.
>
> Thanks,
> Alex Wang,
>
>
> On Thu, Jul 3, 2014 at 12:53 AM, Han Zhou <zhouhan at gmail.com> wrote:
>>
>> That's helpful. But after deleting the more inclusive flow I still
>> cannot delete the "zombie" flow. It might be there are still more
>> overlapping flows.
>> So, I tried ovs-dpctl del-flows, and all the "zombie" flows are gone :)
>>
>> On Wed, Jul 2, 2014 at 10:28 PM, Alex Wang <alexw at nicira.com> wrote:
>> > The tcp field is missing, could you try 'ovs-dpctl dump-flow -m' to get
>> > all fields.  And use it as input to 'ovsdpctl flow-del'
>> >
>> > Thanks,
>> > Alex Wang,
>> >
>> >
>> > On Wed, Jul 2, 2014 at 1:22 AM, Han Zhou <zhouhan at gmail.com> wrote:
>> >>
>> >> Hi Alex,
>> >>
>> >> On Wed, Jul 2, 2014 at 2:30 PM, Alex Wang <alexw at nicira.com> wrote:
>> >> >
>> >> >
>> >> >
>> >> > On Tue, Jul 1, 2014 at 7:38 PM, Han Zhou <zhouhan at gmail.com> wrote:
>> >> >>
>> >> >> Hi Alex,
>> >> >>
>> >> >> That's cool!
>> >> >> Just one more question.
>> >> >> >    Due to the race condition in userspace, there is chance that
>> >> >> > two
>> >> >> >    overlapping megaflows could be installed in datapath.  And this
>> >> >> >    causes userspace unable to delete the less inclusive megaflow
>> >> >> > flow
>> >> >> >    even after it timeout, since the flow_del logic will stop at
>> >> >> > the
>> >> >> >    first match of masked flow.
>> >> >>
>> >> >> Does it mean if the more inclusive megaflow (say A) is deleted, then
>> >> >> the less inclusive megaflow (say B) can be deleted? If so, I can
>> >> >> have
>> >> >> a workaround without updating OVS version: I can find out the more
>> >> >> inclusive megaflow and manually delete flows with ovs-dpctl in order
>> >> >> (A -> B), then warning logs should stop, right?
>> >> >
>> >> >
>> >> > Right.  Note you should prevent the relevant traffic from installing
>> >> > the
>> >> > 'more inclusive' flow between deletions.
>> >> >
>> >>
>> >> I did find out a more inclusive mega-flow, but failed when trying to
>> >> delete that one:
>> >> # ovs-dpctl del-flow system at ovs-system
>> >>
>> >>
>> >> "skb_priority(0),in_port(2),eth(src=30:f7:0d:9b:64:41,dst=78:45:c4:fb:c2:2f),eth_type(0x0800),ipv4(src=10.120.139.226/0.0.0.0,dst=10.120.116.69/0.0.0.0,proto=6/0,tos=0/0,ttl=61/0,frag=no/0xff)"
>> >> 2014-07-02T08:16:29Z|00001|dpif|WARN|system at ovs-system: failed to
>> >> flow_del (Invalid argument)
>> >>
>> >>
>> >> skb_priority(0),in_port(2),eth(src=30:f7:0d:9b:64:41,dst=78:45:c4:fb:c2:2f),eth_type(0x0800),ipv4(src=10.120.139.226,dst=10.120.116.69,proto=6,tos=0,ttl=61,frag=no)
>> >> ovs-dpctl: deleting flow (Invalid argument)
>> >>
>> >> The error is now "Invalid argument". So what's wrong here?
>> >>
>> >> Best regards,
>> >> Han
>> >
>> >
>
>
>
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Hello,

getting the lookalike message on 2.1.3 where the problem described in
the conversation should not take a place:

2014-10-03T17:24:30.429Z|00026|dpif(revalidator_11)|WARN|system at ovs-system:
failed to flow_del (No such file or directory)
skb_priority(0),in_port(2),skb_mark(0),eth(src=xx:xx:xx:xx:xx:xx,dst=yy:yy:yy:yy:yy:yy),eth_type(0x0800),ipv4(src=zz.zz.zz.zz,dst=ii.jj.kk.ll,proto=6,tos=0,ttl=118,frag=no),tcp(src=nnn,dst=mmm),tcp_flags(0x018)


Preconditions are following:
  - 30k installed non-overlapping ip mask flows, ttl=4h,
  - 3k dp flows,
  - moderate traffic, on about 200mbit and hitting 2000prefixes/s.

The error appears long before flow` expiration time, so I think that
there is something wrong. Also even with very low flow_add ratio (~
5/s) I am getting moderately high cpu consumption by vswitchd with
such a setup, on about 50% of single Xeon core, comparing to 20% for
proactive-only match for same traffic with small number of installed
rules (~100).



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