Re: [PATCH v6 net-next 00/13] tcp: BIG TCP implementation

[Alexander H Duyck <alexander.duyck@gmail.com>]

On Mon, 2022-05-09 at 20:32 -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> This series implements BIG TCP as presented in netdev 0x15:
> 
> https://netdevconf.info/0x15/session.html?BIG-TCP
> 
> Jonathan Corbet made a nice summary: https://lwn.net/Articles/884104/
> 
> Standard TSO/GRO packet limit is 64KB
> 
> With BIG TCP, we allow bigger TSO/GRO packet sizes for IPv6 traffic.
> 
> Note that this feature is by default not enabled, because it might
> break some eBPF programs assuming TCP header immediately follows IPv6 header.
> 
> While tcpdump recognizes the HBH/Jumbo header, standard pcap filters
> are unable to skip over IPv6 extension headers.
> 
> Reducing number of packets traversing networking stack usually improves
> performance, as shown on this experiment using a 100Gbit NIC, and 4K MTU.
> 
> 'Standard' performance with current (74KB) limits.
> for i in {1..10}; do ./netperf -t TCP_RR -H iroa23  -- -r80000,80000 -O MIN_LATENCY,P90_LATENCY,P99_LATENCY,THROUGHPUT|tail -1; done
> 77           138          183          8542.19    
> 79           143          178          8215.28    
> 70           117          164          9543.39    
> 80           144          176          8183.71    
> 78           126          155          9108.47    
> 80           146          184          8115.19    
> 71           113          165          9510.96    
> 74           113          164          9518.74    
> 79           137          178          8575.04    
> 73           111          171          9561.73    
> 
> Now enable BIG TCP on both hosts.
> 
> ip link set dev eth0 gro_max_size 185000 gso_max_size 185000
> for i in {1..10}; do ./netperf -t TCP_RR -H iroa23  -- -r80000,80000 -O MIN_LATENCY,P90_LATENCY,P99_LATENCY,THROUGHPUT|tail -1; done
> 57           83           117          13871.38   
> 64           118          155          11432.94   
> 65           116          148          11507.62   
> 60           105          136          12645.15   
> 60           103          135          12760.34   
> 60           102          134          12832.64   
> 62           109          132          10877.68   
> 58           82           115          14052.93   
> 57           83           124          14212.58   
> 57           82           119          14196.01   
> 
> We see an increase of transactions per second, and lower latencies as well.
> 
> v6: fix a compilation error for CONFIG_IPV6=n in
>     "net: allow gso_max_size to exceed 65536", reported by kernel bots.
> 
> v5: Replaced two patches (that were adding new attributes) with patches
>     from Alexander Duyck. Idea is to reuse existing gso_max_size/gro_max_size
> 
> v4: Rebased on top of Jakub series (Merge branch 'tso-gso-limit-split')
>     max_tso_size is now family independent.
> 
> v3: Fixed a typo in RFC number (Alexander)
>     Added Reviewed-by: tags from Tariq on mlx4/mlx5 parts.
> 
> v2: Removed the MAX_SKB_FRAGS change, this belongs to a different series.
>     Addressed feedback, for Alexander and nvidia folks.
> 
> 
> Alexander Duyck (2):
>   net: allow gso_max_size to exceed 65536
>   net: allow gro_max_size to exceed 65536
> 
> Coco Li (2):
>   ipv6: Add hop-by-hop header to jumbograms in ip6_output
>   mlx5: support BIG TCP packets
> 
> Eric Dumazet (9):
>   net: add IFLA_TSO_{MAX_SIZE|SEGS} attributes
>   net: limit GSO_MAX_SIZE to 524280 bytes
>   tcp_cubic: make hystart_ack_delay() aware of BIG TCP
>   ipv6: add struct hop_jumbo_hdr definition
>   ipv6/gso: remove temporary HBH/jumbo header
>   ipv6/gro: insert temporary HBH/jumbo header
>   net: loopback: enable BIG TCP packets
>   veth: enable BIG TCP packets
>   mlx4: support BIG TCP packets

Looked over the changes to my patches and they all look good (sorry for
not catching that myself). This approach addresses all the concerns I
had.

For the series:
Acked-by: Alexander Duyck <alexanderduyck@fb.com>