netdev - Re: Throughput regression with `tcp: refine TSO autosizing`

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Date:	Mon, 02 Feb 2015 13:25:26 -0800
From:	Ben Greear <greearb@...delatech.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	Michal Kazior <michal.kazior@...to.com>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	Network Development <netdev@...r.kernel.org>,
	eyalpe@....mellanox.co.il
Subject: Re: Throughput regression with `tcp: refine TSO autosizing`

On 02/02/2015 10:52 AM, Eric Dumazet wrote:
> On Mon, 2015-02-02 at 11:27 +0100, Michal Kazior wrote:
> 
>> While testing I've had my internal GRO patch for ath10k and no stretch
>> ack patches.
> 
> Thanks for the data, I took a look at it.
> 
> I am afraid this GRO patch might be the problem.
> 
> It seems to break ACK clocking badly (linux stack has a somewhat buggy
> tcp_tso_should_defer(), which relies on ACK being received smoothly, as
> no timer is setup to split the TSO packet.)

It is a big throughput win to have fewer TCP ack packets on
wireless since it is a half-duplex environment.  Is there anything
we could improve so that we can have fewer acks and still get
good tcp stack behaviour?

Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com

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