netdev - Re: [PATCH v3 net-next 4/4] tcp: implement coalescing on backlog queue

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Message-ID: <CADVnQykC-EWpS_VsHCDLGvdTbx5cmitmZTk3TTiGxbTwvMwM8w@mail.gmail.com>
Date:   Wed, 28 Nov 2018 11:46:42 -0500
From:   Neal Cardwell <ncardwell@...gle.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     David Miller <davem@...emloft.net>,
        Netdev <netdev@...r.kernel.org>, jean-louis@...ond.be,
        Yuchung Cheng <ycheng@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH v3 net-next 4/4] tcp: implement coalescing on backlog queue

On Tue, Nov 27, 2018 at 5:42 PM Eric Dumazet <edumazet@...gle.com> wrote:
>
> In case GRO is not as efficient as it should be or disabled,
> we might have a user thread trapped in __release_sock() while
> softirq handler flood packets up to the point we have to drop.
>
> This patch balances work done from user thread and softirq,
> to give more chances to __release_sock() to complete its work
> before new packets are added the the backlog.
>
> This also helps if we receive many ACK packets, since GRO
> does not aggregate them.
>
> This patch brings ~60% throughput increase on a receiver
> without GRO, but the spectacular gain is really on
> 1000x release_sock() latency reduction I have measured.
>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Neal Cardwell <ncardwell@...gle.com>
> Cc: Yuchung Cheng <ycheng@...gle.com>
> ---

Acked-by: Neal Cardwell <ncardwell@...gle.com>

Thanks!

neal