From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934131AbcDLVkO (ORCPT ); Tue, 12 Apr 2016 17:40:14 -0400 Received: from mail2.candelatech.com ([208.74.158.173]:39671 "EHLO mail2.candelatech.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752175AbcDLVkL (ORCPT ); Tue, 12 Apr 2016 17:40:11 -0400 Subject: Re: TCP reaching to maximum throughput after a long time To: Eric Dumazet References: <1460472764.6473.589.camel@edumazet-glaptop3.roam.corp.google.com> <570D0E94.3080006@candelatech.com> <570D566B.8050302@candelatech.com> <1460492253.6473.596.camel@edumazet-glaptop3.roam.corp.google.com> <570D5944.5070100@candelatech.com> <1460492999.6473.599.camel@edumazet-glaptop3.roam.corp.google.com> Cc: "Machani, Yaniv" , netdev , "David S. Miller" , Eric Dumazet , Neal Cardwell , Yuchung Cheng , Nandita Dukkipati , open list , "Kama, Meirav" From: Ben Greear Organization: Candela Technologies Message-ID: <570D6B39.3050605@candelatech.com> Date: Tue, 12 Apr 2016 14:40:09 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 MIME-Version: 1.0 In-Reply-To: <1460492999.6473.599.camel@edumazet-glaptop3.roam.corp.google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/12/2016 01:29 PM, Eric Dumazet wrote: > On Tue, 2016-04-12 at 13:23 -0700, Ben Greear wrote: > >> It worked well enough for years that I didn't even know other algorithms were >> available. It was broken around 4.0 time, and I reported it to the list, >> and no one seemed to really care enough to do anything about it. I changed >> to reno and ignored the problem as well. >> >> It is trivially easy to see the regression when using ath10k NIC, and from this email >> thread, I guess other NICs have similar issues. > > Since it is so trivial, why don't you start a bisection ? I vaguely remember doing a bisect, but I can't find any email about that, so maybe I didn't. At any rate, it is somewhere between 3.17 and 4.0. From memory, it was between 3.19 and 4.0, but I am not certain of that. Neil's suggestion, from the thread below, is that it was likely: "605ad7f tcp: refine TSO autosizing" Here is previous email thread: https://www.mail-archive.com/netdev@vger.kernel.org/msg80803.html This one has a link to a pcap I made at the time: https://www.mail-archive.com/netdev@vger.kernel.org/msg80890.html > > I asked a capture, I did not say ' switch to Reno or whatever ', right ? > > Guessing is nice, but investigating and fixing is better. > > Do not assume that nothing can be done, please ? Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com