[Mini-NDN] [EXT]Re: Problems measuring elapsed time in MiniNDN experiment

[Junxiao Shi]

Hi Saurab

I think OP is recording the end time after face.processEvents() returns.
This is unusual but valid according to API: face.processEvents() should
block until there’s nothing scheduled on the asio::io_context. This means,
suppose this is the only Interest on the face, face.processEvent() should
return when the Interest is either satisfied or expired.

I don’t know what’s causing the problem though.

Yours, Junxiao

On Wed, Sep 9, 2020 at 15:20 Saurab Dulal (sdulal) <sdulal at memphis.edu>
wrote:

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> Hi Anurag,
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> Where are you computing "m_sTimeDiff"? are you computing it inside the
> callback? if the data is received, "onData" should be called and I assume
> you are computing it there? If not, you will not get the right value.
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> Additionally, you can also use NDN_LOG. For every log message, it begins
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> (this is what I do most of the time).
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> Regards,
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> Saurab Dulal
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> ------------------------------
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> *From:* Mini-NDN <mini-ndn-bounces at lists.cs.ucla.edu> on behalf of Lan
> Wang (lanwang) <lanwang at memphis.edu>
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> *Sent:* Tuesday, September 8, 2020 11:37 PM
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> *To:* Anurag Muttur via Mini-NDN <mini-ndn at lists.cs.ucla.edu>
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> *Subject:* [Mini-NDN] Problems measuring elapsed time in MiniNDN
> experiment
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> Begin forwarded message:
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> The attached message has been automatically discarded.
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> *From: *Andre Dexheimer Carneiro <andre.dexheimer at inf.ufrgs.br>
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> *Subject: **Problems measuring elapsed time in MiniNDN experiment*
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> *Date: *September 8, 2020 at 9:41:38 PM CDT
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> *To: *mini-ndn at lists.cs.ucla.edu
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> Hi,
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> I am writing an experiment which instantiates NDN producers and consumers
> as an attempt to simulate a specific scenario with multiple hosts. However,
> I can't seem to measure the elapsed time correctly, my code right now is:
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>   dtBegin   = std::chrono::steady_clock::now();
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>   m_face.expressInterest(interest, bind(&Consumer::onData, this,   _1, _2),
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>      bind(&Consumer::onNack, this, _1, _2), bind(&Consumer::onTimeout,
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>   // processEvents will block until the requested data is received or a
> timeout occurs
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>   m_face.processEvents();
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>   dtEnd       = std::chrono::steady_clock::now();
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>   m_sTimeDiff =
> std::chrono::duration_cast<std::chrono::microseconds>(dtEnd -
> dtBegin).count();\
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> -----
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> Everything seems to work fine, with nodes receiving and sending data as
> they should, however the recorded times are usually at around 1000 us,
> which is completely unrealistic as the links have between 2ms and 1000ms
> delay in my topology. Could anybody cast
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> some light into how to get this metric correctly?
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> Thanks in advance.
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> André Dexheimer Carneiro
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> Computer Enginnering - UFRGS
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