From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: loaded router, excessive getnstimeofday in oprofile Date: Thu, 28 Aug 2008 00:39:52 +0200 Message-ID: <20080827223952.GE26610@one.firstfloor.org> References: <87vdxmr53f.fsf@basil.nowhere.org> <48B57BD3.5050206@hp.com> <20080827162735.GW26610@one.firstfloor.org> <20080827.151824.14173512.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: andi@firstfloor.org, rick.jones2@hp.com, johnpol@2ka.mipt.ru, dada1@cosmosbay.com, denys@visp.net.lb, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: David Miller Return-path: Received: from one.firstfloor.org ([213.235.205.2]:55008 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752834AbYH0WhT (ORCPT ); Wed, 27 Aug 2008 18:37:19 -0400 Content-Disposition: inline In-Reply-To: <20080827.151824.14173512.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Aug 27, 2008 at 03:18:24PM -0700, David Miller wrote: > From: Andi Kleen > Date: Wed, 27 Aug 2008 18:27:35 +0200 > > > > Those banks really want to crank down on latency - to the point they > > > start disabling interrupt coalescing. I bet they'd toss anything out > > > they could to shave another microsecond. > > > > This change would actually likely lower their latency. > > They want the timestamps, but they want it to match when the packet > arrived at their system as closely as is reasonably possible. Then they should use hardware time stamps which are increasingly available (e.g. current Intel e1000 design has them and I expect others too). -Andi