From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next] tcp: change IPv6 flow-label upon receiving spurious retransmission Date: Fri, 31 Aug 2018 23:03:41 -0700 (PDT) Message-ID: <20180831.230341.857947500854204329.davem@davemloft.net> References: <20180829215356.235336-1-ycheng@google.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: edumazet@google.com, netdev@vger.kernel.org, ncardwell@google.com To: ycheng@google.com Return-path: Received: from shards.monkeyblade.net ([23.128.96.9]:43974 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726044AbeIAKO3 (ORCPT ); Sat, 1 Sep 2018 06:14:29 -0400 In-Reply-To: <20180829215356.235336-1-ycheng@google.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Yuchung Cheng Date: Wed, 29 Aug 2018 14:53:56 -0700 > Currently a Linux IPv6 TCP sender will change the flow label upon > timeouts to potentially steer away from a data path that has gone > bad. However this does not help if the problem is on the ACK path > and the data path is healthy. In this case the receiver is likely > to receive repeated spurious retransmission because the sender > couldn't get the ACKs in time and has recurring timeouts. > > This patch adds another feature to mitigate this problem. It > leverages the DSACK states in the receiver to change the flow > label of the ACKs to speculatively re-route the ACK packets. > In order to allow triggering on the second consecutive spurious > RTO, the receiver changes the flow label upon sending a second > consecutive DSACK for a sequence number below RCV.NXT. > > Signed-off-by: Yuchung Cheng > Signed-off-by: Neal Cardwell > Signed-off-by: Eric Dumazet Applied.