From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: loaded router, excessive getnstimeofday in oprofile Date: Wed, 27 Aug 2008 09:07:47 -0700 Message-ID: <48B57BD3.5050206@hp.com> References: <200808220457.40892.denys@visp.net.lb> <20080826201406.GA24827@2ka.mipt.ru> <48B46B48.7030609@cosmosbay.com> <20080826205158.GA15266@2ka.mipt.ru> <87vdxmr53f.fsf@basil.nowhere.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Evgeniy Polyakov , Eric Dumazet , Denys Fedoryshchenko , netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Andi Kleen Return-path: Received: from g1t0029.austin.hp.com ([15.216.28.36]:30684 "EHLO g1t0029.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758152AbYH0QHw (ORCPT ); Wed, 27 Aug 2008 12:07:52 -0400 In-Reply-To: <87vdxmr53f.fsf@basil.nowhere.org> Sender: netdev-owner@vger.kernel.org List-ID: Andi Kleen wrote: > Evgeniy Polyakov writes: > >>Yup, this innocent toys can end up with this such behaviour on modern >>highly loaded machines. > > > I and also other people had some patches to move the time stamp > measuring into the socket. This way the time stamping didn't need to > be enabled on all packets, only on those that actually end up at a > socket that requires the time stamp. > > Unfortunately DaveM didn't like it because some bank wanted > different semantics, see the discussion in > http://thread.gmane.org/gmane.linux.network/91679 > > Perhaps you can find out which bank it was and send them a bill for > your CPU time ;-) 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. rick jones