netdev - Re: NAT performance regression caused by vlan GRO support

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Message-ID: <20190405105151.7csiro6ib5zpaqsd@breakpoint.cc>
Date:   Fri, 5 Apr 2019 12:51:51 +0200
From:   Florian Westphal <fw@...len.de>
To:     Toke Høiland-Jørgensen <toke@...hat.com>
Cc:     Toshiaki Makita <makita.toshiaki@....ntt.co.jp>,
        Felix Fietkau <nbd@....name>,
        Rafał Miłecki <zajec5@...il.com>,
        Toshiaki Makita <toshiaki.makita1@...il.com>,
        netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Stefano Brivio <sbrivio@...hat.com>,
        Sabrina Dubroca <sd@...asysnail.net>,
        David Ahern <dsahern@...il.com>, Jo-Philipp Wich <jo@...n.io>,
        Koen Vandeputte <koen.vandeputte@...ntric.com>
Subject: Re: NAT performance regression caused by vlan GRO support

Toke Høiland-Jørgensen <toke@...hat.com> wrote:
> As a first approximation, maybe just:
> 
> if (!has_hardware_cksum_offload(netdev) && link_rate(netdev) <= 1Gbps)
>   disable_gro();

I don't think its a good idea.  For local delivery case, there is no
way to avoid the checksum cost, so might as well have GRO enabled.