netdev - Re: One question about __tcp_select

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Message-ID: <6b7c1a82-e253-09bd-fd3e-363ce6a84653@gmail.com>
Date:   Tue, 17 Apr 2018 07:43:48 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Wang Jian <jianjian.wang1@...il.com>, netdev@...r.kernel.org
Subject: Re: One question about __tcp_select_window()



On 04/17/2018 06:53 AM, Wang Jian wrote:
> I test the fix with 4.17.0-rc1+ and it seems work.
> 
> 1. iperf -c IP -i 20 -t 60 -w 1K
>  with-fix vs without-fix : 1.15Gbits/sec vs 1.05Gbits/sec
> I also try other windows and have similar results.
> 
> 2. Use tcp probe trace snd_wind.
> with-fix vs without-fix: 1245568 vs 1042816
> 
> 3. I don't see extra retransmit/drops.
> 

Unfortunately I have no idea what exact problem you had to solve.

Setting small windows is not exactly the path we are taking.

And I do not know how many side effects your change will have for 'standard' flows
using autotuning or sane windows.