From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Malicki Subject: Re: loaded router, excessive getnstimeofday in oprofile Date: Thu, 28 Aug 2008 02:28:12 -0400 (EDT) Message-ID: <21915755.1327801219904892242.JavaMail.root@ouachita> References: <20080827.201020.17601834.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: andi@firstfloor.org, johnpol@2ka.mipt.ru, dada1@cosmosbay.com, denys@visp.net.lb, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, juhlenko@akamai.com, sammy@sammy.net To: David Miller Return-path: Received: from silene.metacarta.com ([208.80.142.18]:59433 "EHLO silene.metacarta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751543AbYH1Gqi (ORCPT ); Thu, 28 Aug 2008 02:46:38 -0400 In-Reply-To: <20080827.201020.17601834.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: ----- "David Miller" wrote: > > Every application using AF_PACKET sockets gets timestamps by > default. And we do know of several specific cases where the > timestamps are unnecessary. > > Even for other cases, why in the world does a DHCP client need > accurate timestamps? Give me a break. :) > I've worked with systems where SO_TIMESTAMP has been used for H.323 videoconferencing systems to synchronize audio and video where remote systems' timestamps on the protocol streams proved to be inaccurate (based off of different, unsynchronized clocks). I can't see any other realistic use of this, but trying to get timestamps for quasi-realtime protocols may be an important use case - and in that case, you want the time when it hits the interface, NOT when it hits the socket. What utility does the time of hitting the socket get you?