Re: [RFC PATCH 2/2] tcp: Early SYN limit and SYN cookie handling to mitigate SYN floods

Eric Dumazet
2012-05-30T08:24:54Z

On Wed, 2012-05-30 at 10:03 +0200, Hans Schillstrom wrote:

> We have this option running right now, and it gave slightly higher values.
> The upside is only one core is running at 100% load.
>
> To be able to process more SYN an attempt was made to spread them with RPS to
> 2 other cores gave 60% more SYN:s per sec
> i.e. syn filter in NIC sending all irq:s to one core gave ~ 52k syn. pkts/sec
> adding RPS and sending syn to two other core:s gave ~80k syn. pkts/sec
> Adding more cores than two didn't help that much.

When you say 52.000 pkt/s, is that for fully established sockets, or
SYNFLOOD ?

19.23 us to handle _one_ SYN message seems pretty wrong to me, if there
is no contention on listener socket.