Packet drop while using BPF filter

Packet drop while using BPF filter

[Mukesh Yadav]

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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Packet drop while using BPF filter

[Mulyadi Santosa]

Hi Mukesh..

On Wed, Dec 21, 2011 at 01:38, Mukesh Yadav <mukesh.fkd@gmail.com> wrote:
> 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.

I have zero  experience with BPF, so this is just my theory.

In kernel level, (or maybe between kernel and user level), by putting
your odd and even filter, kernel work too hard to separate the packets
into different "queue" or "channel"...or something like that. While in
the mean time, incoming packets are bursting .... This makes buffers
filled up fast.

How about this... just filter anything that match your target
MAC....fed this up to the user level application and let your
application do the odd and even IP filtering?

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

Packet drop while using BPF filter

[Mukesh Yadav]

Thanks Mulyadi,
Yeah that a final alternative.  Actually I was looking for some optimized
way of getting packet filtered at kernel level using BPF filter.


On 21 December 2011 06:22, Mulyadi Santosa <mulyadi.santosa@gmail.com>wrote:

> Hi Mukesh..
>
> On Wed, Dec 21, 2011 at 01:38, Mukesh Yadav <mukesh.fkd@gmail.com> wrote:
> > 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.
>
> I have zero  experience with BPF, so this is just my theory.
>
> In kernel level, (or maybe between kernel and user level), by putting
> your odd and even filter, kernel work too hard to separate the packets
> into different "queue" or "channel"...or something like that. While in
> the mean time, incoming packets are bursting .... This makes buffers
> filled up fast.
>
> How about this... just filter anything that match your target
> MAC....fed this up to the user level application and let your
> application do the odd and even IP filtering?
>
> --
> regards,
>
> Mulyadi Santosa
> Freelance Linux trainer and consultant
>
> blog: the-hydra.blogspot.com
> training: mulyaditraining.blogspot.com
>



-- 
Cheers
Mukesh Yadav
Senior Software Engineer
Plot6 Sector 18
Aricent
Gurgaon
Mob: 9953024169
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Packet drop while using BPF filter

[Mulyadi Santosa]

Hi Mukesh

On Wed, Dec 21, 2011 at 12:25, Mukesh Yadav <mukesh.fkd@gmail.com> wrote:
> Thanks Mulyadi,
> Yeah that a final alternative.? Actually I was looking for some optimized
> way of getting packet filtered at kernel level using BPF filter.

You're welcome. Logically, your code should have no problem, but well
it seems that the implementation in BPF is not so good somewhere.

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

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@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
>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

Packet drop while using BPF filter

[Mukesh Yadav]

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@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@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
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Packet drop while using BPF filter

[Raghavendra D Prabhu]

* On Sat, Dec 24, 2011 at 09:57:50PM +0530, Mukesh Yadav <mukesh.fkd@gmail.com> wrote:
>Hi  Raghavendra,
>
>" /proc/sys/net/core/bpf_jit_**enable " is not present on machine. Seems
>kernel need to be configured for these.
Yes, it is a fairly new option -- CONFIG_BPF_JIT=y

>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.
That is generally how it is done. The core which handles packets 
initially
handles the interrupts too. Do you mean all non-network 
interrupts were happening on same core ? Then give irqbalance a 
shot.

>
>Thanks
>Mukesh
>
>On 22 December 2011 19:18, Raghavendra D Prabhu <raghu.prabhu13@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@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
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