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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 564E1C2B9F4 for ; Tue, 22 Jun 2021 17:46:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39EA961166 for ; Tue, 22 Jun 2021 17:46:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232323AbhFVRsO (ORCPT ); Tue, 22 Jun 2021 13:48:14 -0400 Received: from imap2.colo.codethink.co.uk ([78.40.148.184]:58636 "EHLO imap2.colo.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232536AbhFVRr6 (ORCPT ); Tue, 22 Jun 2021 13:47:58 -0400 Received: from cpc152649-stkp13-2-0-cust121.10-2.cable.virginm.net ([86.15.83.122] helo=[192.168.0.18]) by imap2.colo.codethink.co.uk with esmtpsa (Exim 4.92 #3 (Debian)) id 1lvkSw-0000OM-AE; Tue, 22 Jun 2021 18:45:38 +0100 Subject: Re: [PATCH v2 0/5] riscv: improving uaccess with logs from network bench To: Akira Tsukamoto , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org References: <5a5c07ac-8c11-79d3-46a3-a255d4148f76@gmail.com> From: Ben Dooks Organization: Codethink Limited. Message-ID: Date: Tue, 22 Jun 2021 18:45:37 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/06/2021 13:05, Akira Tsukamoto wrote: > On 6/22/2021 5:30 PM, Ben Dooks wrote: >> On 19/06/2021 12:21, Akira Tsukamoto wrote: >>> Optimizing copy_to_user and copy_from_user. >>> >>> I rewrote the functions in v2, heavily influenced by Garry's memcpy >>> function [1]. >>> The functions must be written in assembler to handle page faults manually >>> inside the function. >>> >>> With the changes, improves in the percentage usage and some performance >>> of network speed in UDP packets. >>> Only patching copy_user. Using the original memcpy. >>> >>> All results are from the same base kernel, same rootfs and same >>> BeagleV beta board. >>> >>> Comparison by "perf top -Ue task-clock" while running iperf3. >> >> I did a quick test on a SiFive Unmatched with IO to an NVME. >> >> before: cached-reads=172.47MB/sec, buffered-reads=135.8MB/sec >> with-patch: cached-read=s177.54Mb/sec, buffered-reads=137.79MB/sec >> >> That was just one test run, so there was a small improvement. I am >> sort of surprised we didn't get more of a win from this. >> >> perf record on hdparm shows that it spends approx 15% cpu time in >> asm_copy_to_user. Does anyone have a benchmark for this which just >> looks at copy/to user? if not should we create one? > > Thanks for the result on the Unmatched with hdparm. Have you tried > iperf3? I will see if there is iperf3 installed. I've not done much other than try booting it and then try booting it with a kernel i've built from upstream. > The 15% is high, is it before or with-patch? Can't remember, I did this more to find out if the copy to/from user was going to show up in the times for hdparm. > Akira > -- Ben Dooks http://www.codethink.co.uk/ Senior Engineer Codethink - Providing Genius https://www.codethink.co.uk/privacy.html