netdev - Re: [PATCH net-next 0/6] tcp: remove non GSO code

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Date:   Tue, 20 Feb 2018 15:21:37 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Oleksandr Natalenko <oleksandr@...alenko.name>
Cc:     Eric Dumazet <edumazet@...gle.com>,
        "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Neal Cardwell <ncardwell@...gle.com>,
        Yuchung Cheng <ycheng@...gle.com>,
        Soheil Hassas Yeganeh <soheil@...gle.com>
Subject: Re: [PATCH net-next 0/6] tcp: remove non GSO code

On Tue, 2018-02-20 at 21:45 +0100, Oleksandr Natalenko wrote:
> On úterý 20. února 2018 21:09:37 CET Eric Dumazet wrote:
> > Also you can tune your NIC to accept few MSS per GSO/TSO packet
> > 
> > ip link set dev eth0 gso_max_segs 2
> > 
> > So even if TSO/GSO is there, BBR should not use sk->sk_gso_max_segs to
> > size its bursts, since burt sizes are also impacting GRO on the
> > receiver.
> 
> net-next + 7 patches (6 from the patchset + this one).

My latest patch (fixing BBR underestimation of cwnd)
was meant for net tree, on a NIC where SG/TSO/GSO) are disabled.

( ie when sk->sk_gso_max_segs is not set to 'infinite' )

It is packet scheduler independent really.

Tested here with pfifo_fast, TSO/GSO off.

Before patch :
for f in {1..5}; do ./super_netperf 1 -H lpaa24 -- -K bbr; done
    691  (ss -temoi shows cwnd is stuck around 6 )
    667
    651
    631
    517

After patch :
# for f in {1..5}; do ./super_netperf 1 -H lpaa24 -- -K bbr; done
   1733 (ss -temoi shows cwnd is around 386 )
   1778
   1746
   1781
   1718

Thanks.