netdev - Re: [PATCH net-next 0/2] tcp_bbr: Improving TCP BBR performance for WiFi and cellular networks

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Date:   Thu, 24 Jan 2019 08:36:36 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Priyaranjan Jha <priyarjha@...gle.com>,
        David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net-next 0/2] tcp_bbr: Improving TCP BBR performance for
 WiFi and cellular networks



On 01/23/2019 12:04 PM, Priyaranjan Jha wrote:
> Ack aggregation is quite prevalent with wifi, cellular and cable modem
> link tchnologies, ACK decimation in middleboxes, and common offloading
> techniques such as TSO and GRO, at end hosts. Previously, BBR was often
> cwnd-limited in the presence of severe ACK aggregation, which resulted in
> low throughput due to insufficient data in flight.
> 
> To achieve good throughput for wifi and other paths with aggregation, this
> patch series implements an ACK aggregation estimator for BBR, which
> estimates the maximum recent degree of ACK aggregation and adapts cwnd
> based on it. The algorithm is further described by the following
> presentation:
> https://datatracker.ietf.org/meeting/101/materials/slides-101-iccrg-an-update-on-bbr-work-at-google-00
> 
> (1) A preparatory patch, which refactors bbr_target_cwnd for generic
>     inflight provisioning.
> 
> (2) Implements BBR ack aggregation estimator and adapts cwnd based
>     on measured degree of ACK aggregation.
> 
> Priyaranjan Jha (2):
>   tcp_bbr: refactor bbr_target_cwnd() for general inflight provisioning
>   tcp_bbr: adapt cwnd based on ack aggregation estimation
> 
>  include/net/inet_connection_sock.h |   4 +-
>  net/ipv4/tcp_bbr.c                 | 180 +++++++++++++++++++++++++----
>  2 files changed, 161 insertions(+), 23 deletions(-)
> 

Very nice work Priyaranjan
Thanks !

Signed-off-by: Eric Dumazet <edumazet@...gle.com>