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

kk yap yapkke at stanford.edu
Wed May 18 22:22:51 UTC 2011


Thanks for the very fast response.  TY tested the code and it worked.


On 18 May 2011 12:55, Ethan Jackson <ethan at nicira.com> wrote:
>> 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?
> I should have responded to this question in my previous email.  Packet
> statistics are recorded in a best-effort fashion.  In general they
> should be accurate, but there is no hard guarantee that they are
> especially in certain edge cases involving complex flow tables
> including resubmit actions.  In short, you should expect accurate
> statistics from OVS noting the aforementioned caveat.
> Thanks again for reporting this bug.
> Ethan

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