[Nfd-dev] NDN-RTC: NFD processing logs

Junxiao Shi shijunxiao at email.arizona.edu
Sun Feb 8 10:13:40 PST 2015

Hi Peter

On Feb 05 we identified a few possible places that can cause delay:

   - network
   - kernel
   - C++ memory allocator
   - Boost.Asio
   - UdpFace or its base class DatagramFace

The logs you gathered appear to be complete according to what we requested.
@Davide, can you gain some insights from the logs?

Regarding the 30-second interval pattern discovered by John: the only
30-second interval I know of in NFD is UDP face idle_timeout, when this
option is unset in nfd.conf.
Every 30 seconds, UdpChannel will enumerate all its faces, and close all
faces that haven't received anything. There's no evidence that any face is
created, because FaceIds are consistent throughout the logs. However this
scheduled event will take some CPU time, but I don't believe it can cause a
delay of more than 5ms.
To rule out this possibility, adjust face_system.udp.idle_timeout option in
nfd.conf (to "50"), and test again.

>From an earlier log snippet, I notice that the NFD version you are running
is older than September 2014.
Please use git-HEAD version for any bug reports.

As you told me on Feb 05, you will create a traffic simulator that can have
same traffic pattern as NdnCon that can run on headless Ubuntu servers.
I'll be able to test on controlled environment when that tool becomes

Yours, Junxiao

On Fri, Feb 6, 2015 at 4:14 PM, Gusev, Peter <peter at remap.ucla.edu> wrote:

>  Hi guys,
>  So I’ve run setup today and gathered logs.
> I’ve setup NFDs with the following settings
> *...*
> * default_level NONE  Forwarder DEBUG  UdpFace TRACE …*
>  And then I run tcpdump on each machine like this:
> *$ sudo tcpdump -w ~/dump.pcap -i en4 udp port 6363*
>  Here is the summary on “problematic” packets:
> https://docs.google.com/document/d/11JAPHI6J4jD6mibMRuWd1EvzP-NY_F2osM2vDF2VaGM/edit?usp=sharing
>  All the log files and tcpdumps you can find here:
> https://www.dropbox.com/s/1d277xbhqs97o66/logs.zip?dl=0
>  Thanks for all the help!
> Thanks,
> --
> Peter Gusev
> Programmer/Analyst @ REMAP, UCLA
> peter at remap.ucla.edu
> +1 213 5872748
> peetonn_ (skype)
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