'dropped due to full socket buffers' by SNMP

[Eugene Grosbein]

22.01.2021 19:28, Victor Gamov wrote:

> On 22.01.2021 13:21, Eugene Grosbein wrote:
>> 22.01.2021 17:02, Victor Gamov wrote:
>>
>>> No link overload: this host attached to network via 10G ix0, many
>>> VLANs on this ix0 and some sender on every VLAN sends multicast
>>> traffic to this host.  Total input traffic about 1Gbit/s
>>
>> What FreeBSD version do you use currently? Do you use IPv6 for UDP or
>> IPv4 only?
> 
> 
> FreeBSD 12.2-STABLE r366543 GENERIC  amd64
> 
> UDP-4 only

In case of IPv4 UDP the counter "dropped due to full socket buffers"
is increased for incoming packets only. Therefore, the problem is in a code
processing incoming stream(s): either it locks for long time on something,
or it just has no enough raw CPU horsepower to deal with incoming stream.

Look at "top -SHPI" CPU counters, if your CPU cores are loaded evenly;
if some of cores became overloaded sometimes. You should also draw per-cpu load graphs.
(f.e. sysctl kern.cp_times)