[Nfd-dev] Maximum FIB size

[Bruno Ricci]

Dear all

I ran some tests using the same script I used, but always using the same 
IP address, and I successfully managed to add 10000 FIB entries.

Looks like the number of faces (and thus, I think, the file descriptor 
limit) was indeed the problem. I still cannot figure out why the problem 
didn't happen always at the same point, but at least now I am aware of 
what the problem might be.

Thank you all for the help.

Best regards

Bruno

On 14/01/2016 01:22, Davide Pesavento wrote:
> On Wed, Jan 13, 2016 at 11:29 PM, Bruno Ricci <bruno.ricci at uniroma2.it> wrote:
>> Hi guys,
>>
>> first of all, thank you for your answers.
>>
>> All we did was run a bash script that calls nfdc register. All routes are
>> random string of 16 chars, and are set towards a random IP address using
>> UDP. As simple as (pseudocode)
>>
>> for i in 1..100000
>> do
>>    ip=random(3.3.3.3)
>>    name=random(16)
>>    nfdc register ndn:/$name  udp://$ip
>>    sleep 1
>> done
>>
>> This runs fine without errors (at least with the default debug level), until
>> NFD silently crashes. As Junxiao pointed out, maybe the problem relies on
>> the number of faces, and not on the FIB size (I honestly haven't thought
>> about that, thanks for pointing that out). I will try tomorrow morning at
>> work to re run the script reducing the faces number, and to run NFD inside
>> gdb.
>>
>> I will keep you posted, thanks again.
>>
>> Bruno
>>
>
> Hi Bruno,
>
> I'm pretty sure you went well over the maximum number of open file
> descriptors allowed by the system, e.g. it's normally set to 1024 on
> ubuntu linux. This happens because for every prefix you register,
> you're also implicitly creating a new face. And each face needs a
> socket, which means an open file descriptor. So basically you're
> trying to open 100k fds... (or a bit less if some of the generated IPs
> are duplicates).
>
> HTH!
>
> Ciao,
> Davide
>

-- 
----------------------------------------------------------------------
Bruno Ricci, Ph.D.
Post-doc Researcher
CNIT - Consorzio Nazionale Interuniversitario per le Telecomunicazioni
Department of Electronic Engineering, University of Rome "Tor Vergata"
Website: http://netgroup.uniroma2.it/bruno-ricci/
Tel.: +39 06 7259 7445