netdev - Re: [PATCH v6 net-next 0/2] tcp: Redundant Data Bundling (RDB)

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Date:	Wed, 9 Mar 2016 18:27:09 -0800
From:	Yuchung Cheng <ycheng@...gle.com>
To:	Jonas Markussen <jonassm@....uio.no>
Cc:	Bendik Rønning Opstad <bro.devel@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Neal Cardwell <ncardwell@...gle.com>,
	Andreas Petlund <apetlund@...ula.no>,
	Carsten Griwodz <griff@...ula.no>,
	Pål Halvorsen <paalh@...ula.no>,
	Kristian Evensen <kristian.evensen@...il.com>,
	Kenneth Klette Jonassen <kennetkl@....uio.no>
Subject: Re: [PATCH v6 net-next 0/2] tcp: Redundant Data Bundling (RDB)

On Wed, Mar 9, 2016 at 5:45 PM, Jonas Markussen <jonassm@....uio.no> wrote:
>
>> On 10 Mar 2016, at 01:20, Yuchung Cheng <ycheng@...gle.com> wrote:
>>
>> PS. I don't understand how (old) RDB can masquerade the losses by
>> skipping DUPACKs. Perhaps an example helps. Suppose we send 4 packets
>> and the last 3 were (s)acked. We perform RDB to send a packet that has
>> previous 4 payloads + 1 new byte. The sender still gets the loss
>> information?
>>
>
> If I’ve understood you correctly, you’re talking about sending 4
> packets and the first one is lost?
>
> In this case, RDB will not only bundle on the last/new packet but also
> as it sends packet 2 (which will contain 1+2), packet 3 (1+2+3)
> and packet 4 (1+2+3+4).
>
> So the fact that packet 1 was lost is masqueraded when it is
> recovered by packet 2 and there won’t be any gap in the SACK window
> indicating that packet 1 was lost.
I see. Thanks for the clarification.

So my question is still if thin-stream app has enough inflight to use
ack-triggered recovery. i.e., it has to send at least twice within an
RTT.

Also have you tested this with non-Linux receivers? Thanks.

>
> Best regards,
> Jonas Markussen