Packet drop while using BPF filter

Mukesh Yadav mukesh.fkd at gmail.com
Sat Dec 24 11:27:50 EST 2011


Hi  Raghavendra,

" /proc/sys/net/core/bpf_jit_**enable " is not present on machine. Seems
kernel need to be configured for these.
Btw CPU scaling issue is resolved. Packet drop was because all interrupt
handling was happening on core where packets were getting drop. Tuning
system for interrupt handling using smp_affinity resolved the issue.

Thanks
Mukesh

On 22 December 2011 19:18, Raghavendra D Prabhu <raghu.prabhu13 at gmail.com>wrote:

> 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
>>
>
>  ______________________________**_________________
>> Kernelnewbies mailing list
>> Kernelnewbies at kernelnewbies.**org <Kernelnewbies at kernelnewbies.org>
>> http://lists.kernelnewbies.**org/mailman/listinfo/**kernelnewbies<http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies>
>>
>
> --------------------------
> Raghavendra Prabhu
> GPG Id : 0xD72BE977
> Fingerprint: B93F EBCB 8E05 7039 CD3C A4B8 A616 DCA1 D72B E977
> www: wnohang.net
>



-- 
Cheers
Mukesh Yadav
Senior Software Engineer
Plot6 Sector 18
Aricent
Gurgaon
Mob: 9953024169
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20111224/be5ab93c/attachment.html 


More information about the Kernelnewbies mailing list