From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Anatoly Sivov" Subject: Re: why does skb->tstamp use getnstimeofday? Date: Sun, 15 Jan 2012 23:55:23 +0400 Message-ID: References: <1326645750.5287.48.camel@edumazet-laptop> <1326653813.5287.84.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: "Eric Dumazet" Return-path: Received: from smtp24.mail.ru ([94.100.176.177]:55902 "EHLO smtp24.mail.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751778Ab2AOTyZ (ORCPT ); Sun, 15 Jan 2012 14:54:25 -0500 In-Reply-To: <1326653813.5287.84.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: > TCP stack doesnt use skb->tstamp/jtime_t, for example, but jiffies. Some CA engines asks for RTT calculation with skb->tstamp. They state about it by setting TCP_CONG_RTT_STAMP flag in their struct tcp_congestion_ops instances. > For what kind of application or protocol do you feel there could be a > problem ? I don't insist on problems are here, just want to mark that there could be a problem with these CA engines in the case of "big ntp adjustment".