[ovs-discuss] Inaccurate statistics in flow_removed struct using OpenvSwitch

Ethan Jackson ethan at nicira.com
Wed May 18 19:49:44 UTC 2011


Thanks for reporting this issue.  I've CCd you on a fix which should
be reviewed and merged shortly.

Ethan

On Tue, May 17, 2011 at 17:55, kk yap <yapkke at stanford.edu> wrote:
> Hi,
>
> We are using OVS as a software switch, with last commit
> aa77020c361ffba011d7ec9603caa55aaa01cd1f.
>
> When a flow of ten pings is sent across the switch, OVS counted 19
> packets instead.  The setup is
>           veth1 ---- veth0 --- OVS --- eth1
>
> IP address is assigned to veth1.  The attached pcap file is capture
> with the any interface, i.e., each ICMP packet will appear thrice (at
> veth1, veth0 and eth1).  The controller is local and at port 6633.
> Looking at the control traffic, packet 777 and 779  are flow removed
> for the ICMP flows, and they both shows packet count of 19 despite of
> having only ten packets in the flows.
>
> Looking at the code, ovs-openflowd returns facet + stat as packet
> count for the flow removed.  The number recorded by facet is correct,
> but the sum of the value exceed the real value.  This occurs at the
> facet_update_stats function.  What is the purpose of the addition?
> Can we expect accurate statistics from OVS?
>
> Thanks.
>
> Regards
> KK and TY
>
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