netdev - Re: [PATCH v2 net-next] tcp: fix slow start after idle vs TSO/GSO

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Message-ID: <CADVnQynwaW0DEJE+kiLeaJ59rBaZ-uE2dWOyx+RH-LXxTBr_Ug@mail.gmail.com>
Date:	Fri, 21 Aug 2015 21:43:22 -0400
From:	Neal Cardwell <ncardwell@...gle.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Yuchung Cheng <ycheng@...gle.com>
Subject: Re: [PATCH v2 net-next] tcp: fix slow start after idle vs TSO/GSO

On Fri, Aug 21, 2015 at 3:30 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> slow start after idle might reduce cwnd, but we perform this
> after first packet was cooked and sent.
>
> With TSO/GSO, it means that we might send a full TSO packet
> even if cwnd should have been reduced to IW10.
>
> Moving the SSAI check in skb_entail() makes sense, because
> we slightly reduce number of times this check is done,
> especially for large send() and TCP Small queue callbacks from
> softirq context.
>
> As Neal pointed out, we also need to perform the check
> if/when receive window opens.
...
> 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>

Looks good to me. Thanks, Eric!

neal
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