[erlang-questions] Gen_UDP Packet Loss

[Tony Rogvall]

On 30 jul 2014, at 21:14, Lee Sylvester <lee.sylvester@REDACTED> wrote:

> Okay, I’ll try that.  Just so you know, though, I also receive packet loss with TCP, only at 35 clients +, rather than a dismal 3+
> 
Could please explain what you mean with "receive packet loss with TCP" ?

Do you mean that you see the packet error on the network stat ?

Have you checked your equipment, connected the cables correctly, power cycled everything :-)

/Tony


> Lee
> 
> 
> On 30 Jul 2014, at 20:12, Jesper Louis Andersen <jesper.louis.andersen@REDACTED> wrote:
> 
>> There are two buffers here. The kernel has a buffer and the Erlang VM has a buffer. You are setting the Erlang VMs buffers only. If the kernels buffer fills up, it drops packets, because it is allowed to do so with UDP (UDP is not reliable). Linux doesn't have too many easy ways to see this. But you can do netstat -c --udp -an and watch for large recv-q's.
>> 
>> 
>> On Wed, Jul 30, 2014 at 9:09 PM, Lee Sylvester <lee.sylvester@REDACTED> wrote:
>> Thanks.  How does that make a difference over setting it in the app, though?
>> 
>> Thanks,
>> Lee
>> 
>> 
>> On 30 Jul 2014, at 20:06, Max Lapshin <max.lapshin@REDACTED> wrote:
>> 
>>> I've spent lot of time to make capturing of 600 mbit/s of udp traffic without loss.
>>> 
>>> Don't specify buffer size in erlang, use system variables.
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> sysctl -w net.core.rmem_max=1048576
>>> sysctl -w net.core.rmem_default=1048576
>>> sysctl -w net.ipv4.udp_mem="8388608 12582912 16777216"
>> 
>> 
>> 
>> 
>> -- 
>> J.
> 
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