[dnsdist] Tweaking kernel paramaters for heavy loaded site with dnsdist

[Aleš Rygl]

Hi all,

I would like to ask you for recommendations regarding network performance 
optimization for a server running Linux with dnsdist. I am still experincing 
RcvbufErrors even if my setting for receive/send buffers is far from default:

~# sysctl -p
net.ipv4.conf.all.log_martians = 1
vm.swappiness = 0
net.ipv6.conf.all.autoconf = 0
net.ipv6.conf.all.accept_ra = 0
net.core.rmem_max = 536870912
net.core.wmem_max = 536870912
net.core.rmem_default = 212992
net.core.somaxconn = 4096
net.core.optmem_max = 25165824
net.core.netdev_max_backlog = 131072
net.ipv4.ip_local_port_range = 5000 65000


~# netstat -su | grep -A6 "^Udp:"
Udp:
    28972173474 packets received
    182081 packets to unknown port received.
    1186918205 packet receive errors
    28764385384 packets sent
    RcvbufErrors: 1186719867
    InCsumErrors: 198338

I am receiwing about 20-25 kqps of UDP traffic.

Is there something else I can do apart from buying better hw?

Thanks
Regards
Ales