From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755662Ab2FUF7J (ORCPT ); Thu, 21 Jun 2012 01:59:09 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:62826 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755389Ab2FUF7H (ORCPT ); Thu, 21 Jun 2012 01:59:07 -0400 Subject: Re: How does SACK or FACK determine the time to start fast retransmition? From: Eric Dumazet To: LovelyLich Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Date: Thu, 21 Jun 2012 07:59:02 +0200 Message-ID: <1340258342.4604.3983.camel@edumazet-glaptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2012-06-20 at 22:31 +0800, LovelyLich wrote: > HI all, > When tcp uses reno as its congestion control algothim, it uses > tp->sacked_out as dup-ack. When the third dup-ack(under default > condition) comes, tcp will initiate its fast retransmition. > But how about sack ? Some tcp experts out there only catch tcp related stuff if Subject includes TCP. You might resend your mail on netdev (not sure lkml will really help) with following subject : [RFC] tcp: How does SACK or FACK determine the time to start fast retransmission? To get more traction.