Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759936Ab3JPAeO (ORCPT ); Tue, 15 Oct 2013 20:34:14 -0400 Received: from mail-pd0-f178.google.com ([209.85.192.178]:57945 "EHLO mail-pd0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759828Ab3JPAeN (ORCPT ); Tue, 15 Oct 2013 20:34:13 -0400 Message-ID: <1381883650.2045.92.camel@edumazet-glaptop.roam.corp.google.com> Subject: Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's From: Eric Dumazet To: Joe Perches Cc: Ingo Molnar , Neil Horman , linux-kernel@vger.kernel.org, sebastien.dugue@bull.net, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org Date: Tue, 15 Oct 2013 17:34:10 -0700 In-Reply-To: <1381854064.22110.16.camel@joe-AO722> References: <1381510298-20572-1-git-send-email-nhorman@tuxdriver.com> <20131012172124.GA18241@gmail.com> <20131014202854.GH26880@hmsreliant.think-freely.org> <1381785560.2045.11.camel@edumazet-glaptop.roam.corp.google.com> <1381789127.2045.22.camel@edumazet-glaptop.roam.corp.google.com> <1381790278.16896.2.camel@joe-AO722> <1381790686.2045.24.camel@edumazet-glaptop.roam.corp.google.com> <1381790982.16896.7.camel@joe-AO722> <20131015074123.GB25493@gmail.com> <1381854064.22110.16.camel@joe-AO722> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 873 Lines: 24 On Tue, 2013-10-15 at 09:21 -0700, Joe Perches wrote: > Ingo, Eric _showed_ that the prefetch is good here. > How about looking at a little optimization to the minimal > prefetch that gives that level of performance. Wait a minute, my point was to remind that main cost is the memory fetching. Its nice to optimize cpu cycles if we are short of them, but in the csum_partial() case, the bottleneck is the memory. Also I was wondering on the implications of changing reads order, as it might fool cpu predictions. I do not particularly care about finding the right prefetch stride, I think Intel guys know better than me. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/