From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yuchung Cheng Subject: [PATCH 0/2 net-next] tcp: reducing lost retransmits in recovery Date: Wed, 1 Jul 2015 14:11:13 -0700 Message-ID: <1435785075-20600-1-git-send-email-ycheng@google.com> Cc: netdev@vger.kernel.org, Yuchung Cheng To: davem@davemloft.net Return-path: Received: from mail-ig0-f180.google.com ([209.85.213.180]:36161 "EHLO mail-ig0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751675AbbGAVLX (ORCPT ); Wed, 1 Jul 2015 17:11:23 -0400 Received: by igrv9 with SMTP id v9so83260050igr.1 for ; Wed, 01 Jul 2015 14:11:22 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: This patch series reduces lost retransmits in recovery, in particular when dealing with traffic policers. The main problem is that slow start in recovery under policing can cause massive lost and retransmit storms: any excess sending rate turns into drops. The solution is to avoid doing slow start when lost retransmit is detected and use packet conservation instead. On networks with traffic policers the patches have lowered the TCP loss rates by ~20% from Google servers without latency regressions. Yuchung Cheng (2): tcp: reduce cwnd if retransmit is lost in CA_Loss tcp: PRR uses CRB mode by default and SS mode conditionally net/ipv4/tcp_input.c | 43 +++++++++++++++++++++++-------------------- 1 file changed, 23 insertions(+), 20 deletions(-) -- 2.4.3.573.g4eafbef