help tweaking UDP buffers

[Kaplan]

HI guys. 

I am seeing  "1001605 send buffer errors" on my janus streraming servers:

netstat -suna

IcmpMsg:

    InType3: 139656

    InType8: 860

    InType11: 3

    OutType0: 860

    OutType3: 93680

Udp:

    68108393 packets received

    8177383 packets to unknown port received

    0 packet receive errors

    667765339 packets sent

    0 receive buffer errors

    1001605 send buffer errors

 I've tweaked the following sysctl settings:

sysctl -w net.core.rmem_max=26214400

sysctl -w net.core.rmem_default=26214400

sysctl -w net.core.wmem_default=26214400

sysctl -w net.core.wmem_max=26214400

sysctl -w net.core.optmem_max=26214400

the servers are 16GB dedicated servers solely running Janus. 

any ideas on the tunning?

[Avital Yachin]

Hi,

We tuned our system mainly to forward RTP streams from the Video Room plugin to local UDP ports (i.e. ffmpeg runs on same machine running Janus).

Here are our settings (/etc/sysctl.conf):

net.core.rmem_default = 26214400

net.core.rmem_max = 26214400

net.core.wmem_default = 26214400

net.core.wmem_max = 26214400

net.core.somaxconn = 4096

net.core.netdev_max_backlog = 65536

net.core.optmem_max = 26214400

net.ipv4.udp_mem = 8388608 12582912 16777216

net.ipv4.udp_rmem_min = 16384

net.ipv4.udp_wmem_min = 16384

vm.swappiness=10

Machine is Ubuntu 18.04 with 256GB RAM, but this should work also for much lower amounts of RAM.

[Ju Ju]

this buffers are "per socket" . So setting up 26Mo (13 Mo actually) for a real time service is just a non sense.

what you want is the opposite : not having many packet in buffers and in increase latency.

The issue is elsewhere. Did you start to check  the used bandwidth of your link vs the max bandwidth ? using a snap monitoring tool could help to check the 5 min average bandwidth. For checking burst you need more specific tools.

J