netdev - [PATCH v2 net 0/3] tcp: fix xmit timer rearming to avoid stalls

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Date:   Thu,  3 Aug 2017 09:19:51 -0400
From:   Neal Cardwell <ncardwell@...gle.com>
To:     David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Neal Cardwell <ncardwell@...gle.com>
Subject: [PATCH v2 net 0/3] tcp: fix xmit timer rearming to avoid stalls

This patch series is a bug fix for a TCP loss recovery performance bug
reported independently in recent netdev threads:
    
 (i)  July 26, 2017: netdev thread "TCP fast retransmit issues"
 (ii) July 26, 2017: netdev thread:
       "[PATCH V2 net-next] TLP: Don't reschedule PTO when there's one
       outstanding TLP retransmission"

Many thanks to Klavs Klavsen and Mao Wenan for the detailed reports,
traces, and packetdrill test cases, which enabled us to root-cause
this issue and verify the fix.

- v1 -> v2:
 - In patch 2/3, changed an unclear comment in the pre-existing code
   in tcp_schedule_loss_probe() to be more clear (thanks to Eric Dumazet
   for suggesting we improve this).

Neal Cardwell (3):
  tcp: introduce tcp_rto_delta_us() helper for xmit timer fix
  tcp: enable xmit timer fix by having TLP use time when RTO should fire
  tcp: fix xmit timer to only be reset if data ACKed/SACKed

 include/net/tcp.h     | 10 ++++++++++
 net/ipv4/tcp_input.c  | 30 +++++++++++++++++-------------
 net/ipv4/tcp_output.c | 23 +++++------------------
 3 files changed, 32 insertions(+), 31 deletions(-)

-- 
2.14.0.rc1.383.gd1ce394fe2-goog