From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2772AC3A59C for ; Fri, 16 Aug 2019 14:55:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 042692086C for ; Fri, 16 Aug 2019 14:55:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727467AbfHPOzp (ORCPT ); Fri, 16 Aug 2019 10:55:45 -0400 Received: from foss.arm.com ([217.140.110.172]:57760 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727359AbfHPOzo (ORCPT ); Fri, 16 Aug 2019 10:55:44 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 10321344; Fri, 16 Aug 2019 07:55:44 -0700 (PDT) Received: from [10.1.197.57] (e110467-lin.cambridge.arm.com [10.1.197.57]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id ACB7B3F694; Fri, 16 Aug 2019 07:55:42 -0700 (PDT) Subject: Re: [PATCH] arm64: do_csum: implement accelerated scalar version To: Shaokun Zhang , Will Deacon Cc: Ard Biesheuvel , linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org, ilias.apalodimas@linaro.org, "huanglingyan (A)" , steve.capper@arm.com References: <20190218230842.11448-1-ard.biesheuvel@linaro.org> <20190412095243.GA27193@fuggles.cambridge.arm.com> <41b30c72-c1c5-14b2-b2e1-3507d552830d@arm.com> <20190515094704.GC24357@fuggles.cambridge.arm.com> <440eb674-0e59-a97e-4a90-0026e2327069@hisilicon.com> <20190815164609.GI2015@fuggles.cambridge.arm.com> <37fbc2a3-069d-9f75-f3d0-3eda2efa5c9b@hisilicon.com> From: Robin Murphy Message-ID: Date: Fri, 16 Aug 2019 15:55:41 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <37fbc2a3-069d-9f75-f3d0-3eda2efa5c9b@hisilicon.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 16/08/2019 09:15, Shaokun Zhang wrote: > Hi Will, > > On 2019/8/16 0:46, Will Deacon wrote: >> On Thu, May 16, 2019 at 11:14:35AM +0800, Zhangshaokun wrote: >>> On 2019/5/15 17:47, Will Deacon wrote: >>>> On Mon, Apr 15, 2019 at 07:18:22PM +0100, Robin Murphy wrote: >>>>> On 12/04/2019 10:52, Will Deacon wrote: >>>>>> I'm waiting for Robin to come back with numbers for a C implementation. >>>>>> >>>>>> Robin -- did you get anywhere with that? >>>>> >>>>> Still not what I would call finished, but where I've got so far (besides an >>>>> increasingly elaborate test rig) is as below - it still wants some unrolling >>>>> in the middle to really fly (and actual testing on BE), but the worst-case >>>>> performance already equals or just beats this asm version on Cortex-A53 with >>>>> GCC 7 (by virtue of being alignment-insensitive and branchless except for >>>>> the loop). Unfortunately, the advantage of C code being instrumentable does >>>>> also come around to bite me... >>>> >>>> Is there any interest from anybody in spinning a proper patch out of this? >>>> Shaokun? >>> >>> HiSilicon's Kunpeng920(Hi1620) benefits from do_csum optimization, if Ard and >>> Robin are ok, Lingyan or I can try to do it. >>> Of course, if any guy posts the patch, we are happy to test it. >>> Any will be ok. >> >> I don't mind who posts it, but Robin is super busy with SMMU stuff at the >> moment so it probably makes more sense for you or Lingyan to do it. > > Thanks for restarting this topic, I or Lingyan will do it soon. FWIW, I've rolled up what I had so far and dumped it up into a quick semi-realistic patch here: http://linux-arm.org/git?p=linux-rm.git;a=commitdiff;h=859c5566510c32ae72039aa5072e932a771a3596 So far I'd put most of the effort into the aforementioned benchmarking harness to compare performance and correctness for all the proposed implementations over all reasonable alignment/length combinations - I think that got pretty much finished, but as Will says I'm unlikely to find time to properly look at this again for several weeks. Robin.