netdev - Re: [PATCH v2 next 0/2] tcp: make undo_cwnd mandatory for congestion modules

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Message-Id: <20161121.132033.2109447661537445700.davem@davemloft.net>
Date:   Mon, 21 Nov 2016 13:20:33 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     fw@...len.de
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH v2 next 0/2] tcp: make undo_cwnd mandatory for
 congestion modules

From: Florian Westphal <fw@...len.de>
Date: Mon, 21 Nov 2016 14:18:36 +0100

> highspeed, illinois, scalable, veno and yeah congestion control algorithms
> don't provide a 'cwnd_undo' function.  This makes the stack default to a
> 'reno undo' which doubles cwnd.  However, the ssthresh implementation of
> these algorithms do not halve the slowstart threshold. This causes similar
> issue as the one fixed for dctcp in ce6dd23329b1e ("dctcp: avoid bogus
> doubling of cwnd after loss").
> 
> In light of this it seems better to remove the fallback and make undo_cwnd
> mandatory.
> 
> First patch fixes those spots where reno undo seems incorrect by providing
> .cwnd_undo functions, second patch removes the fallback.

Series applied, thanks for following up on this.