[erlang-questions] Erlang distribution links don't fully utilise available resources - OTP 22.0.2 - Why?

[Dmytro Lytovchenko]

Have a look at your

   - Linux kernel TCP settings
   - Memory throughput Gbit/s (the data is copied several times for sending
   and receiving)
   - Head of the line problem (if receiver doesn't read fast enough, the
   memory will be used to store the unconsumed data)
   - Message size might make some difference, OTP 22 splits packets over
   64k into segments, so they also have to be stored before assembling in the
   destination
   - Kernel CPU time vs User CPU time (network driver and kernel overhead)


On Tue, 18 Jun 2019 at 10:43, Karl Nilsson <kjnilsson@REDACTED> wrote:

> I work with Gerhard (OP) and just thought I'd chime in.
>
> Thanks for the alternative suggestions of using sockets / partisan. At
> some point we will look at this but for now we are working on making the
> best use possible of vanilla distributed erlang links. We do understand
> there is overhead and inherent inefficiencies with using distributed erlang
> for data transfer but isn't it surprising / concerning anyone else that it
> is only able to make use of 27% of total network potential? Would you not
> prefer it to be, say, 50% or even 75% if this is theoretically possible?
>
> So what we'd like to find out is whether there are genuine unsurmountable
> reasons for this or something that can be improved, either by tweaking
> config or by optimisations in the distribution layer.
>
> We will run more tests to get more data to reason about. If anyone has
> suggestions for good tests to run / metrics to inspect that would be very
> welcome.
>
> Cheers
> Karl
>
> On Mon, 17 Jun 2019 at 23:01, Scott Lystig Fritchie <fritchie@REDACTED>
> wrote:
>
>> I've not tried using Partisan for the kind of single sender -> single
>> receiver large blob throughput that y'all are attempting, but Partisan
>> might make better use of high speed local networks in your case.
>>
>> http://partisan.cloud
>>
>> -Scott (standing in for Chris Meiklejohn ^_^)
>>
>> _______________________________________________
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>
>
> --
> *Karl Nilsson*
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