From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753191Ab3JNHtF (ORCPT ); Mon, 14 Oct 2013 03:49:05 -0400 Received: from mail-ea0-f174.google.com ([209.85.215.174]:55680 "EHLO mail-ea0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752850Ab3JNHtE (ORCPT ); Mon, 14 Oct 2013 03:49:04 -0400 Date: Mon, 14 Oct 2013 09:49:00 +0200 From: Ingo Molnar To: Andi Kleen Cc: Neil Horman , linux-kernel@vger.kernel.org, sebastien.dugue@bull.net, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org Subject: Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's Message-ID: <20131014074900.GA20095@gmail.com> References: <1381510298-20572-1-git-send-email-nhorman@tuxdriver.com> <87siw4xy9i.fsf@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87siw4xy9i.fsf@tassilo.jf.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andi Kleen wrote: > Neil Horman writes: > > > Sébastien Dugué reported to me that devices implementing ipoib (which > > don't have checksum offload hardware were spending a significant > > amount of time computing > > Must be an odd workload, most TCP/UDP workloads do copy-checksum > anyways. I would rather investigate why that doesn't work. There's a fair amount of csum_partial()-only workloads, a packet does not need to hit user-space to be a significant portion of the system's workload. That said, it would indeed be nice to hear which particular code path was hit in this case, if nothing else then for education purposes. Thanks, Ingo