netdev - Re: [PATCH v2 net-next] tcp: allow drivers to tweak TSQ logic

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Date:   Sun, 12 Nov 2017 08:39:52 -0500
From:   Neal Cardwell <ncardwell@...gle.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Johannes Berg <johannes.berg@...el.com>,
        Toke Høiland-Jørgensen <toke@...e.dk>,
        Kir Kolyshkin <kir@...nvz.org>
Subject: Re: [PATCH v2 net-next] tcp: allow drivers to tweak TSQ logic

On Sat, Nov 11, 2017 at 6:54 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>
> From: Eric Dumazet <edumazet@...gle.com>
>
> I had many reports that TSQ logic breaks wifi aggregation.
>
> Current logic is to allow up to 1 ms of bytes to be queued into qdisc
> and drivers queues.
>
> But Wifi aggregation needs a bigger budget to allow bigger rates to
> be discovered by various TCP Congestion Controls algorithms.
>
> This patch adds an extra socket field, allowing wifi drivers to select
> another log scale to derive TCP Small Queue credit from current pacing
> rate.
>
> Initial value is 10, meaning that this patch does not change current
> behavior.
>
> We expect wifi drivers to set this field to smaller values (tests have
> been done with values from 6 to 9)
>
> They would have to use following template :
>
> if (skb->sk && skb->sk->sk_pacing_shift != MY_PACING_SHIFT)
>      skb->sk->sk_pacing_shift = MY_PACING_SHIFT;
>
>
> Ref: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1670041
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Johannes Berg <johannes.berg@...el.com>
> Cc: Toke Høiland-Jørgensen <toke@...e.dk>
> Cc: Kir Kolyshkin <kir@...nvz.org>
> ---

Nice. Thanks, Eric!

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

neal