linux-kernel - Re: [PATCH v5 net-next v5 6/6] net: add heuristic for enabling TCP fraglist GRO

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Date: Thu, 2 May 2024 09:33:05 -0600
From: David Ahern <dsahern@...nel.org>
To: Felix Fietkau <nbd@....name>, netdev@...r.kernel.org,
 Eric Dumazet <edumazet@...gle.com>, "David S. Miller" <davem@...emloft.net>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: willemdebruijn.kernel@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 net-next v5 6/6] net: add heuristic for enabling TCP
 fraglist GRO

On 5/2/24 2:44 AM, Felix Fietkau wrote:
> When forwarding TCP after GRO, software segmentation is very expensive,
> especially when the checksum needs to be recalculated.
> One case where that's currently unavoidable is when routing packets over
> PPPoE. Performance improves significantly when using fraglist GRO
> implemented in the same way as for UDP.
> 
> When NETIF_F_GRO_FRAGLIST is enabled, perform a lookup for an established
> socket in the same netns as the receiving device. While this may not
> cover all relevant use cases in multi-netns configurations, it should be
> good enough for most configurations that need this.
> 
> Here's a measurement of running 2 TCP streams through a MediaTek MT7622
> device (2-core Cortex-A53), which runs NAT with flow offload enabled from
> one ethernet port to PPPoE on another ethernet port + cake qdisc set to
> 1Gbps.
> 
> rx-gro-list off: 630 Mbit/s, CPU 35% idle
> rx-gro-list on:  770 Mbit/s, CPU 40% idle
> 
> Acked-by: Paolo Abeni <pabeni@...hat.com>
> Reviewed-by: Eric Dumazet <edumazet@...gle.com>
> Signed-off-by: Felix Fietkau <nbd@....name>
> ---
>  net/ipv4/tcp_offload.c   | 32 ++++++++++++++++++++++++++++++++
>  net/ipv6/tcpv6_offload.c | 35 +++++++++++++++++++++++++++++++++++
>  2 files changed, 67 insertions(+)
> 

Reviewed-by: David Ahern <dsahern@...nel.org>