netdata/health/health.d/tcp_mem.conf

#
# check
# http://blog.tsunanet.net/2011/03/out-of-socket-memory.html
#
# We give a warning when TCP is under memory pressure
# and a critical when TCP is 90% of its upper memory limit
#

    alarm: tcp_memory
       on: ipv4.sockstat_tcp_mem
    class: Utilization
     type: System
component: Network
       os: linux
    hosts: *
     calc: ${mem} * 100 / ${tcp_mem_high}
    units: %
    every: 10s
     warn: ${mem} > (($status >= $WARNING  ) ? ( ${tcp_mem_pressure} * 0.8 ) : ( ${tcp_mem_pressure}   ))
     crit: ${mem} > (($status == $CRITICAL ) ? ( ${tcp_mem_pressure}       ) : ( ${tcp_mem_high} * 0.9 ))
    delay: up 0 down 5m multiplier 1.5 max 1h
  summary: System TCP memory utilization
     info: TCP memory utilization
       to: silent