netdev - Re: software interrupts close to 100 with 9000 tc filter entries

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Date:   Tue, 19 Sep 2017 16:57:25 +0200 (CEST)
From:   Marco Berizzi <pupilla@...ero.it>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     netdev@...r.kernel.org
Subject: Re: software interrupts close to 100 with 9000 tc filter entries

> Eric Dumazet wrote:
> 
> On Tue, 2017-09-19 at 15:28 +0200, Marco Berizzi wrote:
> 
> > Hi Folks,
> > 
> > I'm running linux 4.12.10 x86_64 on a Slackware 14.2 64bit
> > as a simple 4 NIC router. Network throughput processed by
> > this machine is less than 200Mbit/s
> > The cpu model is Intel(R) Xeon(R) CPU 5160 @ 3.00GHz with
> > 2GB ram.
> > 
> > I need to blacklist about 9000 single ip addresses.
> > This is the relevant script to blacklist these ip addresses:
> > 
> > tc qdisc add dev eth0 ingress
> > tc qdisc add dev eth1 ingress
> > 
> > while read -r line
> > do
> >  tc filter add dev eth0 parent ffff: protocol ip prio 50 u32 match ip src $line action drop
> >  tc filter add dev eth1 parent ffff: protocol ip prio 50 u32 match ip src $line action drop
> > done < blacklisted_ip_addresses
> > 
> > After loading these ip addresses, the si (software interrupts)
> > number shown by top is always close to 100
> > If I delete the ingress qdisc on both the device, the si
> > fall down to less than 5
> > 
> > Running the same script with 'only' 700 ip addresses is
> > flawless.
> > 
> > Kindly I would like to ask if am I doing anything in
> > a wrong way or if the hardware is too old for this kind
> > of setup.
> > 
> > I have selected the tc filter setup instead of netfilter
> > one, because I was reading this from iproute2/doc/actions:
> > 
> > A side effect is that we can now get stateless firewalling to work with tc..
> > Essentially this is now an alternative to iptables.
> > I wont go into details of my dislike for iptables at times, but.
> > scalability is one of the main issues; however, if you need stateful
> > classification - use netfilter (for now).
> > 
> > Any response are welcome
> > TIA
> 
> Processing a list of 700 rules per incoming packet is not wise.
> 
> Alternatives :
> 
> *   netfilter with IPSET : This probably can be done with one lookup in a
> table. Probably easiest way to setup.
> 
> *   BPF filter (XDP or TC )

Thanks Eric for the quick response.
For better performance (latency time and network throughput) which is the better
solution? netfilter with ipset or BPF?