netdev - Re: tc filter flow hash question

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Date:	Tue, 30 Jun 2009 14:30:38 +0400
From:	Badalian Vyacheslav <slavon@...telecom.ru>
To:	Jarek Poplawski <jarkao2@...il.com>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: tc filter flow hash question

Jarek Poplawski пишет:
> On Tue, Jun 30, 2009 at 01:49:11PM +0400, Badalian Vyacheslav wrote:
> ...
>   
>> This example not approach? 
>>
>> tc qdisc add dev eth0 root handle 1 htb default 7
>> tc class add dev eth0 parent 1: classid 1:7 htb rate 500mbit ceil 1000mbit prio 3
>> tc qdisc add dev eth0 parent 1:7 handle 10: sfq perturb 10
>>
>> # all traffic go to class 1-7.
>>
>> # Try group traffic by "src,dst" key
>>
>> tc filter add dev eth0 protocol ip parent 10: handle 2 flow hash keys src,dst
>>
>> # all traffic dropped
>>     
>
> Try:
> tc filter add dev eth0 protocol ip parent 10: handle 2 flow hash keys src,dst divisor 1024
>
>   
Outh! Very thanks! I'm so stupid. its simple :(

Also i look in code and see in flow_classify function this lines:

if (f->divisor)
        classid %= f->divisor;

classid generated in up.
Also i see to SFQ code and see that SFQ create 1024 hashes.
If we do not add divisor when added filter rule we get classid > 1024
and its not go to hash of SFQ (my example).
Also divisor must be > 0 because = NaN as i understand.
I not sure that it must be <= 1024 because it may use not in SFQ and i
don't know MAX size of other qdiscs but if it use only in in SFQ i think
we need to check <= SFQ_HASH_DIVISOR also?

Maybe "if" code must be changed to

if (f->divisor && f->divisor > 0)
        classid %= f->divisor;
else
        classid %= 1024;


How you think?
Best regals, Slavon


> Jarek P.
>   
>>>   
>>>       
>>>>> Here are some hints (if we don't mention google ;-)
>>>>> http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.29.y.git;a=commitdiff;h=e5dfb815181fcb186d6080ac3a091eadff2d98fe
>>>>>
>>>>> Regards,
>>>>> Jarek P
>>>>>           
>
>
>   

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