From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [tbench regression fixes]: digging out smelly deadmen. Date: Fri, 31 Oct 2008 22:03:00 +0100 Message-ID: <490B7284.2010003@cosmosbay.com> References: <20081031.005219.141937694.davem@davemloft.net> <20081031.025159.51432990.davem@davemloft.net> <490AE1CD.9040207@cosmosbay.com> <20081031125713.6c6923de@extreme> <20081031201016.GA4748@ioremap.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Stephen Hemminger , David Miller , ilpo.jarvinen@helsinki.fi, rjw@sisk.pl, mingo@elte.hu, s0mbre@tservice.net.ru, a.p.zijlstra@chello.nl, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, efault@gmx.de, akpm@linux-foundation.org To: Evgeniy Polyakov Return-path: In-Reply-To: <20081031201016.GA4748@ioremap.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Evgeniy Polyakov a =E9crit : > On Fri, Oct 31, 2008 at 12:57:13PM -0700, Stephen Hemminger (shemming= er@vyatta.com) wrote: >> Why bother with last_rx at all on loopback. I have been thinking >> we should figure out a way to get rid of last_rx all together. It on= ly >> seems to be used by bonding, and the bonding driver could do the cal= culation >> in its receive handling. >=20 > Not related to the regression: bug will be just papered out by this > changes. Having bonding on loopback is somewhat strange idea, but sti= ll > this kind of changes is an attempt to make a good play in the bad gam= e: > this loopback-only optimization does not fix the problem. >=20 Just to be clear, this change was not meant to be committed. It already was rejected by David some years ago (2005, and 2006) http://www.mail-archive.com/netdev@vger.kernel.org/msg07382.html If you read my mail, I was *only* saying that tbench results can be sen= sible to cache line ping pongs. tbench is a crazy benchmark, and only is a crazy= benchmark. Optimizing linux for tbench sake would be .... crazy ?