netdev - Re: [PATCH 6/6] net: move qdisc ingress filtering on top of netfilter ingress hooks

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Message-ID: <55427F81.4080807@iogearbox.net>
Date:	Thu, 30 Apr 2015 21:16:17 +0200
From:	Daniel Borkmann <daniel@...earbox.net>
To:	Pablo Neira Ayuso <pablo@...filter.org>
CC:	Jamal Hadi Salim <jhs@...atatu.com>,
	Patrick McHardy <kaber@...sh.net>,
	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	netfilter-devel@...r.kernel.org, davem@...emloft.net,
	netdev@...r.kernel.org
Subject: Re: [PATCH 6/6] net: move qdisc ingress filtering on top of netfilter
 ingress hooks

On 04/30/2015 06:36 PM, Pablo Neira Ayuso wrote:
...
> But where are the barriers? These unfounded performance claims are
> simply absurd, qdisc ingress barely performs a bit better just because
> it executes a bit less code and only in the single CPU scenario with
> no rules at all.

I think we're going in circles a bit. :( You are right in saying that
currently, there's a central spinlock, which is worked on to get rid
of, you've seen the patch on the list floating around already. Single
CPU, artificial micro-benchmark, which were done show that you see on
your machine ~613Kpps to ~545Kpps, others have seen it more amplified
as 22.4Mpps to 18.0Mpps drop from __netif_receive_skb_core() up to an
empty dummy u32_classify() rule, which has already been acknowledged
that this gap needs to be improved. Lets call it unfounded then. I
think we wouldn't even have this discussion if we wouldn't try brute
forcing both worlds behind this single static key, or, have both
invoked from within the same layer/list.

Cheers,
Daniel
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