netdev - Re: [PATCH net-next] net: use indirect call wrappers for skb_copy_datagram

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Message-ID: <c56fe143-9229-59a4-1bbd-ab08bf496dcb@gmail.com>
Date:   Wed, 25 Mar 2020 08:14:19 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] net: use indirect call wrappers for
 skb_copy_datagram_iter()

On 3/25/20 4:52 AM, Paolo Abeni wrote:

> 
> I wondered if we could add a second argument for
> 'csum_and_copy_to_iter', but I guess that is a slower path anyway and
> more datapoint would be needed. The patch LGTM, thanks!

Yes, TCP would not need the csum stuff, I suspect the only users
of csum would avoid one indirect call per system call at most,
that is pure noise.

While TCP right now can trigger 45 indirect calls per skb copied to user space,
assuming standard 1500 bytes MTU.

> 
> Acked-by: Paolo Abeni <pabeni@...hat.com>

Thanks !