linux-kernel - Re: [PATCH RFC net-next 2/2] tcp: Add Redundant Data Bundling (RDB)

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Message-ID: <B3A5466A-E881-4EDD-85F1-20E153D92CA8@ifi.uio.no>
Date:	Tue, 27 Oct 2015 19:15:42 +0000
From:	Jonas Markussen <jonassm@....uio.no>
To:	Yuchung Cheng <ycheng@...gle.com>
CC:	Andreas Petlund <apetlund@...ula.no>,
	Neal Cardwell <ncardwell@...gle.com>,
	Bendik Rønning Opstad <bro.devel@...il.com>,
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	James Morris <jmorris@...ei.org>,
	"Hideaki YOSHIFUJI" <yoshfuji@...ux-ipv6.org>,
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	Al Viro <viro@...iv.linux.org.uk>,
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	Bendik Rønning Opstad 
	<bro.devel+kernel@...il.com>
Subject: Re: [PATCH RFC net-next 2/2] tcp: Add Redundant Data Bundling (RDB)

On 26 Oct 2015, at 22:58, Yuchung Cheng <ycheng@...gle.com> wrote:
> but would RDB be voided if this developer turns on RDB then turns on
> Nagle later?

The short answer is answer is "kind of"

My understanding is that Nagle will delay segments until they're
either MSS-sized or until segments "down the pipe" are acknowledged.

As RDB isn't able to bundle if the payload is more than MSS/2, only
an application that that sends data less frequent than an RTT would
still theoretically benefit from RDB even if Nagle is on.

However, in my opinion this is a scenario where Nagle itself is void:

If you transmit more rarely than the RTT, enabling Nagle makes no
difference.

If you transfer more frequent than the RTT, enabling Nagle makes
RDB void.

-Jonas
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