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

Burke, Jeff jburke at remap.ucla.edu
Sun Feb 8 10:33:44 PST 2015

Junxiao & all,

I want to strongly advocate for debugging the actual, running system that we have now, rather than waiting for new code and using  another setup that may or may not exhibit the same problem.

Would it be possible to work with the system in situ with remote access rather than waiting on the ubuntu headless build? (Alternatively, I would rather host you at UCLA for a week, or fedex you our Mac test machines, than write new application that just attempts to replicate the problem.

What Peter was referring to is an Ubuntu port of ndnrtc that will generate the same type of traffic, not a simulator. We need this for testbed deployment.  However, this work is not done yet, and we are trying to move quickly to real world use, and I really don't think we should make this dependent on further app development work.

Thank you,

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 available.

Yours, Junxiao

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

All the log files and tcpdumps you can find here:

Thanks for all the help!


Peter Gusev
Programmer/Analyst @ REMAP, UCLA

peter at remap.ucla.edu<mailto:peter at remap.ucla.edu>
+1 213 5872748<tel:%2B1%20213%205872748>
peetonn_ (skype)

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