From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH net-next] tcp/fq: move back to CLOCK_MONOTONIC Date: Fri, 28 Sep 2018 14:52:17 -0700 Message-ID: <418cfd90-1f5c-abb8-6fbb-0d436ed87374@gmail.com> References: <20180928172844.182542-1-edumazet@google.com> <2e9b1489d291cd0194eb0d65ad8a0e96eb36d5f9.camel@nxp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" , "eric.dumazet@gmail.com" To: Leonard Crestez , "davem@davemloft.net" , "edumazet@google.com" Return-path: Received: from mail-lf1-f65.google.com ([209.85.167.65]:33064 "EHLO mail-lf1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726207AbeI2ESE (ORCPT ); Sat, 29 Sep 2018 00:18:04 -0400 Received: by mail-lf1-f65.google.com with SMTP id o21-v6so6084291lfe.0 for ; Fri, 28 Sep 2018 14:52:22 -0700 (PDT) In-Reply-To: <2e9b1489d291cd0194eb0d65ad8a0e96eb36d5f9.camel@nxp.com> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 09/28/2018 02:27 PM, Leonard Crestez wrote: > On Fri, 2018-09-28 at 10:28 -0700, Eric Dumazet wrote: >> In the recent TCP/EDT patch series, I switched TCP and sch_fq >> clocks from MONOTONIC to TAI, in order to meet the choice done >> earlier for sch_etf packet scheduler. >> >> But sure enough, this broke some setups were the TAI clock >> jumps forward (by almost 50 year...), as reported >> by Leonard Crestez. >> >> If we want to converge later, we'll probably need to add >> an skb field to differentiate the clock bases, or a socket option. >> >> In the meantime, an UDP application will need to use CLOCK_MONOTONIC >> base for its SCM_TXTIME timestamps if using fq packet scheduler. >> >> Fixes: 72b0094f9182 ("tcp: switch tcp_clock_ns() to CLOCK_TAI base") >> Fixes: 142537e41923 ("net_sched: sch_fq: switch to CLOCK_TAI") >> Fixes: fd2bca2aa789 ("tcp: switch internal pacing timer to CLOCK_TAI") >> Signed-off-by: Eric Dumazet >> Reported-by: Leonard Crestez > > Tested-by: Leonard Crestez > > Fixes the problem reported earlier when applied on top of next-20180928 > Thanks again ;)