[ovs-dev] [PATCH V2 2/4] bfd: Implements forwarding_if_rx

Ethan Jackson ethan at nicira.com
Sat Aug 17 03:10:25 UTC 2013


> I think there can be jitters. Since we do not update the rx_detect_time at
> the exact time instant when it timeout, it is possible that "forwarding"
> flag becomes false when "bfd/show" is called at "time_msec() >
> rx_detect_time" time.

I'm not sure I understand.  Seems to me like it should work, but I
must be missing something.  Let's discuss it on Monday in person.

Ethan

>
>
>>
>> > +    if (diff < 0) {
>> > +        VLOG_WARN("rx_packets count is smaller than last time.");
>> > +    }
>> > +    bfd->rx_packets = rx_packets;
>> > +    bfd->has_rx = (diff > 0);
>> > +    incr = bfd_rx_interval(bfd) * bfd->mult;
>> > +    bfd->rx_detect_time = (incr > 2000 ? incr : 2000) + time_msec();
>>
>> This would be easier to read as MAX(incr, 2000).  Also it deserves a
>> comment explaining why we're setting 2000 as the minimum
>> rx_detect_time.  That number seems awfully high to me at any rate, I'd
>> feel better if we set it to 1000, and made (in a separate patch) made
>> ofproto-dpif pull stats from the datapath at least once every 800ms so
>> we have time to grab our stats and update the bfd module.
>
>
>
> I'll add the comment.
>
> I'll adjust accordingly and send another patch for changing the pull stats
> rate in ofproto-dpif.



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