[erlang-questions] UDP receive performance

Lukas Larsson lukas@REDACTED
Thu Jun 21 09:46:09 CEST 2018


On Wed, Jun 20, 2018 at 10:00 PM Rich Neswold <rich.neswold@REDACTED>
wrote:

> On Wed, Jun 20, 2018 at 12:07 PM Lukas Larsson <lukas@REDACTED> wrote:
>
>> So if anyone is running a performance critical UDP server that has set
>> the "recbuf" to a high value, I really recommend that you lower the
>> "buffer" size to something close to the max expected packet size.
>>
>
> That's interesting because the official documentation says:
>
> "It is recommended to have val(buffer) >= max(val(sndbuf),val(recbuf)) to
> avoid performance issues because of unnecessary copying."
>
>
> Maybe the documentation is wrong because that doesn't make much sense;
> sndbuf and recbuf are sent to the kernel and are supposed to be bigger than
> the user's buffer.
>

I think that part of the documentation is mainly written with TCP in mind,
not UDP. Also, following the docs works fine if it weren't for the bug
uncovered in this mail thread. I'll see what I can do about making the docs
better.
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