Re: filter performance/optimization questions

Linux Advanced Routing and Traffic Control

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yepp, hashing is done, for every type C class (/24), there are around 300 of
these, and all are redirected to a more specific table, according to the
documentation.

now i have a question about this, too. to me it's not clear how these filters
are looked up.

at first, there is that default table 800::, where i create these 'hashing
filters'. if i have 300 of them, how are they processed? if a packet comes in,
what happens? are they looked up in the same order i created them? like in
iptables?

then, if say, one filter matched, the more specific filter table is looked up,
the key being the last octet of the ip address (specified by the mask
0x000000ff). it looks up the right entry in the table, and it know in which
flow (in which class) it should put the packet in. right?

now what if i have to filters? one with, say, a source port of 25 specified,
the other one with port 80.

these are some 'subquestions' :) the main question is the optimisation of
course :) i was just wondering how things are done.

Andreas Klauer wrote:
> On Wed, Feb 08, 2006 at 07:29:57PM +0200, Imre Gergely wrote:
>> i did some tests with esfq (that brought down the classes to around 150), but
>> the filters remained, and the load was still 100%. and i get some packet loss
>> because of that. not much, around 1-2%, but it's enough :)
>>
>> is there something i could do to bring the load down?
> 
> Are the filters already hashed? If not, that's the first thing I'd try. 
> There was a section on that on www.lartc.org. (Hmmm, seems to be down.).
> 
> http://www.linux.org/docs/ldp/howto/Adv-Routing-HOWTO/lartc.adv-filter.hashing.html
> 
> HTH
> Andreas Klauer
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> 

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