netdev - Re: [PATCH v3 net-next 0/4] net: batched receive in GRO path

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Date:   Wed, 14 Nov 2018 23:22:37 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Edward Cree <ecree@...arflare.com>,
        linux-net-drivers@...arflare.com, davem@...emloft.net
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH v3 net-next 0/4] net: batched receive in GRO path

On 11/14/2018 10:07 AM, Edward Cree wrote:
>
> Conclusion:
> * TCP b/w is 16.5% faster for traffic which cannot be coalesced by GRO.
>

But only for traffic that actually was perfect GRO candidate, right ?

Now what happens if all the packets you are batching are hitting different TCP sockets ?

(DDOS attack patterns)

By the time we build a list of 64 packets, the first packets in the list wont be anymore
in L1 cache (32 KB 8-way associative typically), and we will probably have cache trashing.