c - LibPCap & Packet Drops - Linux -


my app uses libpcap capture udp packets various sources. app has heavy computational work (ballpark ~2 seconds)... during time app not 'reading' libpcap. leading packet drops, i'm struggling understand why. kernel not dropping packets & think socket buffers should large enough.

the interface receiving ~1000 packets per second. max packet size ~600 bytes. let's call 1mb/s (overestimate).

i've set libpcap buffer size 4mib (passing libpcap bytes) , snapshot length ~600 bytes.

i've modified os params (centos7):

    /proc/sys/net/core/netdev_max_backlog: 10000     /proc/sys/net/core/optmem_max: 8388608     /proc/sys/net/core/rmem_default: 8388608     /proc/sys/net/core/rmem_max: 8388608

result netstat -i:

    iface  mtu  rx-ok     rx-err rx-drp rx-ovr         eno2   1500 558672786 0      0      0

i've tried making of these values larger number of dropped packets doesn't appear reduce.

something might worth mentioning... have tcpdump running on same box capturing same udp packets (the packets multicast). raise questions re when packets gets removed buffers (or parts of stack).

i'm lost here. appreciated.

thanks.


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