netdev - [PATCH v3 net-next 0/4] tcp: take a bit more care of backlog stress

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Date:   Tue, 27 Nov 2018 14:41:59 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Jean-Louis Dupond <jean-louis@...ond.be>,
        Neal Cardwell <ncardwell@...gle.com>,
        Yuchung Cheng <ycheng@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH v3 net-next 0/4] tcp: take a bit more care of backlog stress

While working on the SACK compression issue Jean-Louis Dupond
reported, we found that his linux box was suffering very hard
from tail drops on the socket backlog queue.

First patch hints the compiler about sack flows being the norm.

Second patch changes non-sack code in preparation of the ack
compression.

Third patch fixes tcp_space() to take backlog into account.

Fourth patch is attempting coalescing when a new packet must
be added to the backlog queue. Cooking bigger skbs helps
to keep backlog list smaller and speeds its handling when
user thread finally releases the socket lock.

v3: Neal/Yuchung feedback addressed :
     Do not aggregate if any skb has URG bit set.
     Do not aggregate if the skbs have different ECE/CWR bits

v2: added feedback from Neal : tcp: take care of compressed acks in tcp_add_reno_sack() 
    added : tcp: hint compiler about sack flows
	added : tcp: make tcp_space() aware of socket backlog

Eric Dumazet (4):
  tcp: hint compiler about sack flows
  tcp: take care of compressed acks in tcp_add_reno_sack()
  tcp: make tcp_space() aware of socket backlog
  tcp: implement coalescing on backlog queue

 include/net/tcp.h         |  4 +-
 include/uapi/linux/snmp.h |  1 +
 net/ipv4/proc.c           |  1 +
 net/ipv4/tcp_input.c      | 58 +++++++++++++-----------
 net/ipv4/tcp_ipv4.c       | 92 ++++++++++++++++++++++++++++++++++++---
 5 files changed, 123 insertions(+), 33 deletions(-)

-- 
2.20.0.rc0.387.gc7a69e6b6c-goog