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List:       linux-netdev
Subject:    Re: [PATCH net-next 3/3] tcp: invoke pkts_acked hook on every ACK
From:       Kenneth Klette Jonassen <kennetkl () ifi ! uio ! no>
Date:       2015-04-30 22:20:32
Message-ID: CA++eYdsdW9emVJbiWnCwK5a7STPLsun2X-2edZkpYHEt6KpA6A () mail ! gmail ! com
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> There might be congestion control that assumes pkts_acked > 0 or data
> is cumulatively when this is called. Did you audit that?

HTCP, Illinois, Yeah:
These modules save the pkts_acked count internally and use it to grow
snd_cwnd_cnt in cong_avoid.
This patch ensures they grow by the same count that is passed to cong_avoid().

BIC:
Works well with pkts_acked = 0.

These modules have pkts_acked functions for RTT, but are not using the
acked count:
Cubic, LP, Vegas, Veno, Westwood.

PS on BIC:
Impossibly high counts can potentially overflow ca->delayed_ack to 0
and cause division by zero, e.g. (u32) -30.
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