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Message-ID: <568848da-a702-04ba-4071-2d8a14ac779a@gmail.com>
Date: Sun, 15 Jan 2023 08:45:41 -0700
From: David Ahern <dsahern@...il.com>
To: Xin Long <lucien.xin@...il.com>,
network dev <netdev@...r.kernel.org>
Cc: davem@...emloft.net, kuba@...nel.org,
Eric Dumazet <edumazet@...gle.com>,
Paolo Abeni <pabeni@...hat.com>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
Pravin B Shelar <pshelar@....org>,
Jamal Hadi Salim <jhs@...atatu.com>,
Cong Wang <xiyou.wangcong@...il.com>,
Jiri Pirko <jiri@...nulli.us>,
Pablo Neira Ayuso <pablo@...filter.org>,
Florian Westphal <fw@...len.de>,
Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
Ilya Maximets <i.maximets@....org>,
Aaron Conole <aconole@...hat.com>,
Roopa Prabhu <roopa@...dia.com>,
Nikolay Aleksandrov <razor@...ckwall.org>,
Mahesh Bandewar <maheshb@...gle.com>,
Paul Moore <paul@...l-moore.com>,
Guillaume Nault <gnault@...hat.com>
Subject: Re: [PATCH net-next 00/10] net: support ipv4 big tcp
On 1/13/23 8:31 PM, Xin Long wrote:
> This is similar to the BIG TCP patchset added by Eric for IPv6:
>
> https://lwn.net/Articles/895398/
>
> Different from IPv6, IPv4 tot_len is 16-bit long only, and IPv4 header
> doesn't have exthdrs(options) for the BIG TCP packets' length. To make
> it simple, as David and Paolo suggested, we set IPv4 tot_len to 0 to
> indicate this might be a BIG TCP packet and use skb->len as the real
> IPv4 total length.
>
> This will work safely, as all BIG TCP packets are GSO/GRO packets and
> processed on the same host as they were created; There is no padding
> in GSO/GRO packets, and skb->len - network_offset is exactly the IPv4
> packet total length; Also, before implementing the feature, all those
> places that may get iph tot_len from BIG TCP packets are taken care
> with some new APIs:
>
> Patch 1 adds some APIs for iph tot_len setting and getting, which are
> used in all these places where IPv4 BIG TCP packets may reach in Patch
> 2-7, and Patch 8 implements this feature and Patch 10 adds a selftest
> for it. Patch 9 is a fix in netfilter length_mt6 so that the selftest
> can also cover IPv6 BIG TCP.
>
> Note that the similar change as in Patch 2-7 are also needed for IPv6
> BIG TCP packets, and will be addressed in another patchset.
>
> The similar performance test is done for IPv4 BIG TCP with 25Gbit NIC
> and 1.5K MTU:
>
> No BIG TCP:
> for i in {1..10}; do netperf -t TCP_RR -H 192.168.100.1 -- -r80000,80000 -O MIN_LATENCY,P90_LATENCY,P99_LATENCY,THROUGHPUT|tail -1; done
> 168 322 337 3776.49
> 143 236 277 4654.67
> 128 258 288 4772.83
> 171 229 278 4645.77
> 175 228 243 4678.93
> 149 239 279 4599.86
> 164 234 268 4606.94
> 155 276 289 4235.82
> 180 255 268 4418.95
> 168 241 249 4417.82
>
> Enable BIG TCP:
> ip link set dev ens1f0np0 gro_max_size 128000 gso_max_size 128000
> for i in {1..10}; do netperf -t TCP_RR -H 192.168.100.1 -- -r80000,80000 -O MIN_LATENCY,P90_LATENCY,P99_LATENCY,THROUGHPUT|tail -1; done
> 161 241 252 4821.73
> 174 205 217 5098.28
> 167 208 220 5001.43
> 164 228 249 4883.98
> 150 233 249 4914.90
> 180 233 244 4819.66
> 154 208 219 5004.92
> 157 209 247 4999.78
> 160 218 246 4842.31
> 174 206 217 5080.99
>
> Xin Long (10):
> net: add a couple of helpers for iph tot_len
> bridge: use skb_ip_totlen in br netfilter
> openvswitch: use skb_ip_totlen in conntrack
> net: sched: use skb_ip_totlen and iph_totlen
> netfilter: use skb_ip_totlen and iph_totlen
> cipso_ipv4: use iph_set_totlen in skbuff_setattr
> ipvlan: use skb_ip_totlen in ipvlan_get_L3_hdr
> net: add support for ipv4 big tcp
> netfilter: get ipv6 pktlen properly in length_mt6
> selftests: add a selftest for big tcp
>
> drivers/net/ipvlan/ipvlan_core.c | 2 +-
> include/linux/ip.h | 20 +++
> include/linux/ipv6.h | 9 ++
> include/net/netfilter/nf_tables_ipv4.h | 4 +-
> include/net/route.h | 3 -
> net/bridge/br_netfilter_hooks.c | 2 +-
> net/bridge/netfilter/nf_conntrack_bridge.c | 4 +-
> net/core/gro.c | 6 +-
> net/core/sock.c | 11 +-
> net/ipv4/af_inet.c | 7 +-
> net/ipv4/cipso_ipv4.c | 2 +-
> net/ipv4/ip_input.c | 2 +-
> net/ipv4/ip_output.c | 2 +-
> net/netfilter/ipvs/ip_vs_xmit.c | 2 +-
> net/netfilter/nf_log_syslog.c | 2 +-
> net/netfilter/xt_length.c | 5 +-
> net/openvswitch/conntrack.c | 2 +-
> net/sched/act_ct.c | 2 +-
> net/sched/sch_cake.c | 2 +-
> tools/testing/selftests/net/Makefile | 1 +
> tools/testing/selftests/net/big_tcp.sh | 157 +++++++++++++++++++++
> 21 files changed, 212 insertions(+), 35 deletions(-)
> create mode 100755 tools/testing/selftests/net/big_tcp.sh
>
Thanks for working on this and writing the selftests.
A couple of years ago I was experimenting with a simpler version of this
change (only changed what I needed to run tests). tcpdump (as an example
of packet socket app) was confused about the packet length and reported
truncated packet errors. As I recall that is the only really tricky part
to getting large packets for IPv4.
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