On Fri, 2015-10-09 at 03:50 -0700, Eric Dumazet wrote:
> On Thu, 2015-10-08 at 20:42 -0700, Tom Herbert wrote:
> > On Thu, Oct 8, 2015 at 8:37 AM, Eric Dumazet <eduma...@google.com> wrote:
> > > As promised in last patch series, we implement a better SO_REUSEPORT
> > > strategy, based on cpu affinities if selected by the application.
> > >
> > > We also moved sk_refcnt out of the cache line containing the lookup
> > > keys, as it was considerably slowing down smp operations because
> > > of false sharing. This was simpler than converting listen sockets
> > > to conventional RCU (to avoid sk_refcnt dirtying)
> > >
> > > Could process 6.0 Mpps SYN instead of 4.2 Mpps on my test server.
> > >
> > Is this IPv4, IPv6, or some combination of the two ? :-)
>
> IPv4 only (mostly because I was using trafgen and its csumtcp() only
> deals with IPv4 and I am lazy)
>
> I guess IPv6 one might hit some issues before reaching TCP stack, I do
> not see anything performance related in TCP itself.
>
>
So the answer is : about 800,000 SYN per second in IPV6 with purely DDOS attack
We hit neighbor cache badly.
377.188231] neighbour: ndisc_cache: neighbor table overflow!
[ 377.188234] neighbour: ndisc_cache: neighbor table overflow!
[ 382.193043] net_ratelimit: 36622 callbacks suppressed
[ 382.193046] neighbour: ndisc_cache: neighbor table overflow!
[ 382.193051] neighbour: ndisc_cache: neighbor table overflow!
[ 382.193054] neighbour: ndisc_cache: neighbor table overflow!
59.79% [kernel] [k] queued_spin_lock_slowpath
4.94% [kernel] [k] queued_write_lock_slowpath
2.12% [kernel] [k] sha_transform
1.93% [kernel] [k] ip6_pol_route.isra.47
1.58% [kernel] [k] __neigh_create
1.30% [kernel] [k] inet6_lookup_listener
1.19% [kernel] [k] memcpy_erms
1.09% [kernel] [k] _raw_read_lock_bh
0.88% [kernel] [k] memset_erms
0.85% [kernel] [k] __inet6_lookup_established
0.84% [kernel] [k] ndisc_constructor
0.78% [kernel] [k] fib6_get_table
0.71% [kernel] [k] ip6t_do_table
0.71% [kernel] [k] _raw_read_unlock_bh
0.66% [kernel] [k] _raw_write_lock_bh
0.62% [kernel] [k] fib6_lookup
0.54% [kernel] [k] tcp_make_synack
0.54% [kernel] [k] tcp_conn_request
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