Packet drop while using BPF filter

[Raghavendra D Prabhu]

Hi,

     Have you tried enabling -- /proc/sys/net/core/bpf_jit_enable --
     provides JIT compiled BPF  on 64 bit linux.

* On Wed, Dec 21, 2011 at 12:08:04AM +0530, Mukesh Yadav <mukesh.fkd at gmail.com> wrote:
>Hi Guys,
>
>I am working on user level code which uses BPF filter.
>Solution has two threads and  BPF filter for incoming packets to raw socket
>dedicated to each thread.
>Intent is to divide ingress traffic between two thread based on whether
>dest IP is even or odd.
>
>BPF filters used are:
>Even IP filter :-> tcpdump -i interface 'ether dst <dest mac> && ip[19] &
>0x01 = 0'
>Odd IP filter :->  tcpdump -i interface  'ether dst <dest mac> && ip[19] &
>0x01 = 1'
>
>There is a packet loss for odd IP thread even when CPU is available. Reason
>being packet drop due  recv buffer full.
>Same amount of traffic is well handled by even IP thread(user code being
>same in both), scaling CPU to full 100%.
>
>In odd IP thread, If filter is changed to "tcpdump -i interface  'ether dst
><dest mac> && ip proto 17' ", all goes fine.
>Also CPU usage at kernel drops from 50% to 4 % for a particular amount of
>traffic.
>
>Would appreciate any I/ps for reducing load at kernel for packet
>filtering(Odd/Even IP distribution)
>
>
>Cheers
>Mukesh

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Raghavendra Prabhu
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