Additional consideration is that 1/t1 would involve divide, which will be hard
to implement in hardware…
Regards,
Rong
On 5/26/17, 11:29 AM, "aqm on behalf of Rong Pan (ropan)" <aqm-boun...@ietf.org
on behalf of ro...@cisco.com> wrote:
Michael and Bob,
The depart_rate is inversed in calculation delay….
Delay = queue_length/depart_rate;
Hence, current_qdelay = queue_.byte_length() * PIE-
>avg_dq_time_/DQ_THRESHOLD;
Basically the average dq_time for dequeueing DQ_THRESHOLD is PIE->dq_time;
What is the approximate time to deque the current_qlen?
Current_qlen/DQ_THRESHOLD(what portion is current queue length relative to
DQ_THRESHOLD)? * avg_dq_time.
That is the rationale behind it.
Thanks,
Rong
>> (EWMA) of the rate should be:
>>
>> ewma(depart_rate) = DQ_THRESHOLD ∗ ewma(1/t1,1/t2,1/t3,...)
>> != DQ_THRESHOLD / ewma(t1,t2,t3,...)
>> "
>> PIE uses the second (incorrect) formula. In the review, I discuss how
>> wrong this could be, with an example.
> Thanks, Bob, for pointing this out to me.
>
> Rong, is PIE doing this by intent (if so, what's the reason?) or is
this
> a flaw?
>
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