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Date:   Fri, 20 Nov 2020 18:22:19 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Alexander Duyck <alexander.duyck@gmail.com>
Cc:     netdev@vger.kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net,
        kafai@fb.com, kernel-team@fb.com, edumazet@google.com,
        brakmo@fb.com, alexanderduyck@fb.com, weiwan@google.com
Subject: Re: [net PATCH 0/2] tcp: Address issues with ECT0 not being set in
 DCTCP packets
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On Thu, 19 Nov 2020 13:23:43 -0800 Alexander Duyck wrote:
> This patch set is meant to address issues seen with SYN/ACK packets not
> containing the ECT0 bit when DCTCP is configured as the congestion control
> algorithm for a TCP socket.
> 
> A simple test using "tcpdump" and "test_progs -t bpf_tcp_ca" makes the
> issue obvious. Looking at the packets will result in the SYN/ACK packet
> with an ECT0 bit that does not match the other packets for the flow when
> the congestion control agorithm is switch from the default. So for example
> going from non-DCTCP to a DCTCP congestion control algorithm we will see
> the SYN/ACK IPV6 header will not have ECT0 set while the other packets in
> the flow will. Likewise if we switch from a default of DCTCP to cubic we
> will see the ECT0 bit set in the SYN/ACK while the other packets in the
> flow will not.

Applied, thanks!