netdev - Re: multi bpf filter will impact performance?

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Date:	Tue, 30 Nov 2010 11:01:44 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Rui <wirelesser@...il.com>
Cc:	netdev@...r.kernel.org
Subject: Re: multi bpf filter will impact performance?

Le mardi 30 novembre 2010 à 17:22 +0800, Rui a écrit :

> step 0:
> launch 4 tcpdump processes,each applied a filter to filter out some
> GTP-U packets. seen with 'tcpdump -d', the bpf code has about 100
> lines.

So each incoming packet has to go through your 4 filters, thats a total
of ~400 bpf instructions. (a bit less in average because of the
conditionnal branches)

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