Kernel parameters setting for low latency system

hi all,

I would like to share the setting that I feel it is recommended for most of the low latency system.

# disable the ipv6 setting
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

# reduce swappiness
vm.swappiness = 1

# increase the mmap limit
net.core.wmem_max = 16777216
net.core.rmem_max = 16777216
net.ipv4.tcp_rmem = 4096 87380 16777216
net.ipv4.tcp_wmem = 4096 87380 16777216
vm.max_map_count = 131072

Also, the limit setting
* - nofile 100000
* - memlock unlimited
* - nproc 32768
* - as unlimited

Bash in action: detecting opening port

hi all,

If you are running out of any of the unix/linux utility e.g. netstat or nc to detect the opening port, here is one of the simple trick that can help you to achieve your goal. have fun!

timeout 1 bash -c "cat < /dev/null > /dev/tcp/$SERVER/$port"
if [ "$?" -ne 0 ]
then
    echo "Connection to $SERVER on $port is failed."
else
    echo "Connection to $SERVER to $port is succeeded."
fi