From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754927Ab3KFTAT (ORCPT ); Wed, 6 Nov 2013 14:00:19 -0500 Received: from charlotte.tuxdriver.com ([70.61.120.58]:46707 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752217Ab3KFTAR (ORCPT ); Wed, 6 Nov 2013 14:00:17 -0500 Date: Wed, 6 Nov 2013 13:59:36 -0500 From: Neil Horman To: Eric Dumazet Cc: Dave Jones , linux-kernel@vger.kernel.org, sebastien.dugue@bull.net, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org Subject: Re: [PATCH v2 2/2] x86: add prefetching to do_csum Message-ID: <20131106185936.GA11415@hmsreliant.think-freely.org> References: <1381510298-20572-1-git-send-email-nhorman@tuxdriver.com> <1383751399-10298-1-git-send-email-nhorman@tuxdriver.com> <1383751399-10298-3-git-send-email-nhorman@tuxdriver.com> <20131106153429.GA26336@redhat.com> <20131106155445.GB6357@neilslaptop.think-freely.org> <1383762190.4291.183.camel@edumazet-glaptop2.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1383762190.4291.183.camel@edumazet-glaptop2.roam.corp.google.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Spam-Score: -2.9 (--) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 06, 2013 at 10:23:10AM -0800, Eric Dumazet wrote: > On Wed, 2013-11-06 at 10:54 -0500, Neil Horman wrote: > > > My guess was that the whole comment was made in reference to the fact that > > checksum offload negated all these advantages. Thats not so true anymore, since > > infiniband needs csum in software for ipoib. > > > > I'll fix this up and send a v3, but I'll give it a day in case there are more > > comments first. > > Also please include netdev, I think people there are interested. > Sure, will do in the updated version > I caught this message, but I usually cannot read lkml traffic. > > I wonder why you do not use (and/or change/tune) prefetch_range() > instead of a local definition. > I wanted to look into this further, because I wasn't (yet) sure if it was a bug or not, but from what I can see x86_64 doesn't define ARCH_HAS_PREFECTH. That makes prefetch_range() a nop (I confirmed this via objdump). It seems like we should either define ARCH_HAS_PREFETCH on x86_64, or we should remove the #ifdef from prefetch_range > > >